#include "Python.h" #include "pycore_pymem.h" // _PyTraceMalloc_Config #include #include // malloc() /* Defined in tracemalloc.c */ extern void _PyMem_DumpTraceback(int fd, const void *ptr); /* Python's malloc wrappers (see pymem.h) */ #undef uint #define uint unsigned int /* assuming >= 16 bits */ /* Forward declaration */ static void* _PyMem_DebugRawMalloc(void *ctx, size_t size); static void* _PyMem_DebugRawCalloc(void *ctx, size_t nelem, size_t elsize); static void* _PyMem_DebugRawRealloc(void *ctx, void *ptr, size_t size); static void _PyMem_DebugRawFree(void *ctx, void *ptr); static void* _PyMem_DebugMalloc(void *ctx, size_t size); static void* _PyMem_DebugCalloc(void *ctx, size_t nelem, size_t elsize); static void* _PyMem_DebugRealloc(void *ctx, void *ptr, size_t size); static void _PyMem_DebugFree(void *ctx, void *p); static void _PyObject_DebugDumpAddress(const void *p); static void _PyMem_DebugCheckAddress(const char *func, char api_id, const void *p); static void _PyMem_SetupDebugHooksDomain(PyMemAllocatorDomain domain); #if defined(__has_feature) /* Clang */ # if __has_feature(address_sanitizer) /* is ASAN enabled? */ # define _Py_NO_SANITIZE_ADDRESS \ __attribute__((no_sanitize("address"))) # endif # if __has_feature(thread_sanitizer) /* is TSAN enabled? */ # define _Py_NO_SANITIZE_THREAD __attribute__((no_sanitize_thread)) # endif # if __has_feature(memory_sanitizer) /* is MSAN enabled? */ # define _Py_NO_SANITIZE_MEMORY __attribute__((no_sanitize_memory)) # endif #elif defined(__GNUC__) # if defined(__SANITIZE_ADDRESS__) /* GCC 4.8+, is ASAN enabled? */ # define _Py_NO_SANITIZE_ADDRESS \ __attribute__((no_sanitize_address)) # endif // TSAN is supported since GCC 5.1, but __SANITIZE_THREAD__ macro // is provided only since GCC 7. # if __GNUC__ > 5 || (__GNUC__ == 5 && __GNUC_MINOR__ >= 1) # define _Py_NO_SANITIZE_THREAD __attribute__((no_sanitize_thread)) # endif #endif #ifndef _Py_NO_SANITIZE_ADDRESS # define _Py_NO_SANITIZE_ADDRESS #endif #ifndef _Py_NO_SANITIZE_THREAD # define _Py_NO_SANITIZE_THREAD #endif #ifndef _Py_NO_SANITIZE_MEMORY # define _Py_NO_SANITIZE_MEMORY #endif #ifdef WITH_PYMALLOC #ifdef MS_WINDOWS # include #elif defined(HAVE_MMAP) # include # ifdef MAP_ANONYMOUS # define ARENAS_USE_MMAP # endif #endif /* Forward declaration */ static void* _PyObject_Malloc(void *ctx, size_t size); static void* _PyObject_Calloc(void *ctx, size_t nelem, size_t elsize); static void _PyObject_Free(void *ctx, void *p); static void* _PyObject_Realloc(void *ctx, void *ptr, size_t size); #endif /* bpo-35053: Declare tracemalloc configuration here rather than Modules/_tracemalloc.c because _tracemalloc can be compiled as dynamic library, whereas _Py_NewReference() requires it. */ struct _PyTraceMalloc_Config _Py_tracemalloc_config = _PyTraceMalloc_Config_INIT; static void * _PyMem_RawMalloc(void *ctx, size_t size) { /* PyMem_RawMalloc(0) means malloc(1). Some systems would return NULL for malloc(0), which would be treated as an error. Some platforms would return a pointer with no memory behind it, which would break pymalloc. To solve these problems, allocate an extra byte. */ if (size == 0) size = 1; return malloc(size); } static void * _PyMem_RawCalloc(void *ctx, size_t nelem, size_t elsize) { /* PyMem_RawCalloc(0, 0) means calloc(1, 1). Some systems would return NULL for calloc(0, 0), which would be treated as an error. Some platforms would return a pointer with no memory behind it, which would break pymalloc. To solve these problems, allocate an extra byte. */ if (nelem == 0 || elsize == 0) { nelem = 1; elsize = 1; } return calloc(nelem, elsize); } static void * _PyMem_RawRealloc(void *ctx, void *ptr, size_t size) { if (size == 0) size = 1; return realloc(ptr, size); } static void _PyMem_RawFree(void *ctx, void *ptr) { free(ptr); } #ifdef MS_WINDOWS static void * _PyObject_ArenaVirtualAlloc(void *ctx, size_t size) { return VirtualAlloc(NULL, size, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE); } static void _PyObject_ArenaVirtualFree(void *ctx, void *ptr, size_t size) { VirtualFree(ptr, 0, MEM_RELEASE); } #elif defined(ARENAS_USE_MMAP) static void * _PyObject_ArenaMmap(void *ctx, size_t size) { void *ptr; ptr = mmap(NULL, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); if (ptr == MAP_FAILED) return NULL; assert(ptr != NULL); return ptr; } static void _PyObject_ArenaMunmap(void *ctx, void *ptr, size_t size) { munmap(ptr, size); } #else static void * _PyObject_ArenaMalloc(void *ctx, size_t size) { return malloc(size); } static void _PyObject_ArenaFree(void *ctx, void *ptr, size_t size) { free(ptr); } #endif #define MALLOC_ALLOC {NULL, _PyMem_RawMalloc, _PyMem_RawCalloc, _PyMem_RawRealloc, _PyMem_RawFree} #ifdef WITH_PYMALLOC # define PYMALLOC_ALLOC {NULL, _PyObject_Malloc, _PyObject_Calloc, _PyObject_Realloc, _PyObject_Free} #endif #define PYRAW_ALLOC MALLOC_ALLOC #ifdef WITH_PYMALLOC # define PYOBJ_ALLOC PYMALLOC_ALLOC #else # define PYOBJ_ALLOC MALLOC_ALLOC #endif #define PYMEM_ALLOC PYOBJ_ALLOC typedef struct { /* We tag each block with an API ID in order to tag API violations */ char api_id; PyMemAllocatorEx alloc; } debug_alloc_api_t; static struct { debug_alloc_api_t raw; debug_alloc_api_t mem; debug_alloc_api_t obj; } _PyMem_Debug = { {'r', PYRAW_ALLOC}, {'m', PYMEM_ALLOC}, {'o', PYOBJ_ALLOC} }; #define PYDBGRAW_ALLOC \ {&_PyMem_Debug.raw, _PyMem_DebugRawMalloc, _PyMem_DebugRawCalloc, _PyMem_DebugRawRealloc, _PyMem_DebugRawFree} #define PYDBGMEM_ALLOC \ {&_PyMem_Debug.mem, _PyMem_DebugMalloc, _PyMem_DebugCalloc, _PyMem_DebugRealloc, _PyMem_DebugFree} #define PYDBGOBJ_ALLOC \ {&_PyMem_Debug.obj, _PyMem_DebugMalloc, _PyMem_DebugCalloc, _PyMem_DebugRealloc, _PyMem_DebugFree} #ifdef Py_DEBUG static PyMemAllocatorEx _PyMem_Raw = PYDBGRAW_ALLOC; static PyMemAllocatorEx _PyMem = PYDBGMEM_ALLOC; static PyMemAllocatorEx _PyObject = PYDBGOBJ_ALLOC; #else static PyMemAllocatorEx _PyMem_Raw = PYRAW_ALLOC; static PyMemAllocatorEx _PyMem = PYMEM_ALLOC; static PyMemAllocatorEx _PyObject = PYOBJ_ALLOC; #endif static int pymem_set_default_allocator(PyMemAllocatorDomain domain, int debug, PyMemAllocatorEx *old_alloc) { if (old_alloc != NULL) { PyMem_GetAllocator(domain, old_alloc); } PyMemAllocatorEx new_alloc; switch(domain) { case PYMEM_DOMAIN_RAW: new_alloc = (PyMemAllocatorEx)PYRAW_ALLOC; break; case PYMEM_DOMAIN_MEM: new_alloc = (PyMemAllocatorEx)PYMEM_ALLOC; break; case PYMEM_DOMAIN_OBJ: new_alloc = (PyMemAllocatorEx)PYOBJ_ALLOC; break; default: /* unknown domain */ return -1; } PyMem_SetAllocator(domain, &new_alloc); if (debug) { _PyMem_SetupDebugHooksDomain(domain); } return 0; } int _PyMem_SetDefaultAllocator(PyMemAllocatorDomain domain, PyMemAllocatorEx *old_alloc) { #ifdef Py_DEBUG const int debug = 1; #else const int debug = 0; #endif return pymem_set_default_allocator(domain, debug, old_alloc); } int _PyMem_GetAllocatorName(const char *name, PyMemAllocatorName *allocator) { if (name == NULL || *name == '\0') { /* PYTHONMALLOC is empty or is not set or ignored (-E/-I command line nameions): use default memory allocators */ *allocator = PYMEM_ALLOCATOR_DEFAULT; } else if (strcmp(name, "default") == 0) { *allocator = PYMEM_ALLOCATOR_DEFAULT; } else if (strcmp(name, "debug") == 0) { *allocator = PYMEM_ALLOCATOR_DEBUG; } #ifdef WITH_PYMALLOC else if (strcmp(name, "pymalloc") == 0) { *allocator = PYMEM_ALLOCATOR_PYMALLOC; } else if (strcmp(name, "pymalloc_debug") == 0) { *allocator = PYMEM_ALLOCATOR_PYMALLOC_DEBUG; } #endif else if (strcmp(name, "malloc") == 0) { *allocator = PYMEM_ALLOCATOR_MALLOC; } else if (strcmp(name, "malloc_debug") == 0) { *allocator = PYMEM_ALLOCATOR_MALLOC_DEBUG; } else { /* unknown allocator */ return -1; } return 0; } int _PyMem_SetupAllocators(PyMemAllocatorName allocator) { switch (allocator) { case PYMEM_ALLOCATOR_NOT_SET: /* do nothing */ break; case PYMEM_ALLOCATOR_DEFAULT: (void)_PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, NULL); (void)_PyMem_SetDefaultAllocator(PYMEM_DOMAIN_MEM, NULL); (void)_PyMem_SetDefaultAllocator(PYMEM_DOMAIN_OBJ, NULL); break; case PYMEM_ALLOCATOR_DEBUG: (void)pymem_set_default_allocator(PYMEM_DOMAIN_RAW, 1, NULL); (void)pymem_set_default_allocator(PYMEM_DOMAIN_MEM, 1, NULL); (void)pymem_set_default_allocator(PYMEM_DOMAIN_OBJ, 1, NULL); break; #ifdef WITH_PYMALLOC case PYMEM_ALLOCATOR_PYMALLOC: case PYMEM_ALLOCATOR_PYMALLOC_DEBUG: { PyMemAllocatorEx malloc_alloc = MALLOC_ALLOC; PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &malloc_alloc); PyMemAllocatorEx pymalloc = PYMALLOC_ALLOC; PyMem_SetAllocator(PYMEM_DOMAIN_MEM, &pymalloc); PyMem_SetAllocator(PYMEM_DOMAIN_OBJ, &pymalloc); if (allocator == PYMEM_ALLOCATOR_PYMALLOC_DEBUG) { PyMem_SetupDebugHooks(); } break; } #endif case PYMEM_ALLOCATOR_MALLOC: case PYMEM_ALLOCATOR_MALLOC_DEBUG: { PyMemAllocatorEx malloc_alloc = MALLOC_ALLOC; PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &malloc_alloc); PyMem_SetAllocator(PYMEM_DOMAIN_MEM, &malloc_alloc); PyMem_SetAllocator(PYMEM_DOMAIN_OBJ, &malloc_alloc); if (allocator == PYMEM_ALLOCATOR_MALLOC_DEBUG) { PyMem_SetupDebugHooks(); } break; } default: /* unknown allocator */ return -1; } return 0; } static int pymemallocator_eq(PyMemAllocatorEx *a, PyMemAllocatorEx *b) { return (memcmp(a, b, sizeof(PyMemAllocatorEx)) == 0); } const char* _PyMem_GetCurrentAllocatorName(void) { PyMemAllocatorEx malloc_alloc = MALLOC_ALLOC; #ifdef WITH_PYMALLOC PyMemAllocatorEx pymalloc = PYMALLOC_ALLOC; #endif if (pymemallocator_eq(&_PyMem_Raw, &malloc_alloc) && pymemallocator_eq(&_PyMem, &malloc_alloc) && pymemallocator_eq(&_PyObject, &malloc_alloc)) { return "malloc"; } #ifdef WITH_PYMALLOC if (pymemallocator_eq(&_PyMem_Raw, &malloc_alloc) && pymemallocator_eq(&_PyMem, &pymalloc) && pymemallocator_eq(&_PyObject, &pymalloc)) { return "pymalloc"; } #endif PyMemAllocatorEx dbg_raw = PYDBGRAW_ALLOC; PyMemAllocatorEx dbg_mem = PYDBGMEM_ALLOC; PyMemAllocatorEx dbg_obj = PYDBGOBJ_ALLOC; if (pymemallocator_eq(&_PyMem_Raw, &dbg_raw) && pymemallocator_eq(&_PyMem, &dbg_mem) && pymemallocator_eq(&_PyObject, &dbg_obj)) { /* Debug hooks installed */ if (pymemallocator_eq(&_PyMem_Debug.raw.alloc, &malloc_alloc) && pymemallocator_eq(&_PyMem_Debug.mem.alloc, &malloc_alloc) && pymemallocator_eq(&_PyMem_Debug.obj.alloc, &malloc_alloc)) { return "malloc_debug"; } #ifdef WITH_PYMALLOC if (pymemallocator_eq(&_PyMem_Debug.raw.alloc, &malloc_alloc) && pymemallocator_eq(&_PyMem_Debug.mem.alloc, &pymalloc) && pymemallocator_eq(&_PyMem_Debug.obj.alloc, &pymalloc)) { return "pymalloc_debug"; } #endif } return NULL; } #undef MALLOC_ALLOC #undef PYMALLOC_ALLOC #undef PYRAW_ALLOC #undef PYMEM_ALLOC #undef PYOBJ_ALLOC #undef PYDBGRAW_ALLOC #undef PYDBGMEM_ALLOC #undef PYDBGOBJ_ALLOC static PyObjectArenaAllocator _PyObject_Arena = {NULL, #ifdef MS_WINDOWS _PyObject_ArenaVirtualAlloc, _PyObject_ArenaVirtualFree #elif defined(ARENAS_USE_MMAP) _PyObject_ArenaMmap, _PyObject_ArenaMunmap #else _PyObject_ArenaMalloc, _PyObject_ArenaFree #endif }; #ifdef WITH_PYMALLOC static int _PyMem_DebugEnabled(void) { return (_PyObject.malloc == _PyMem_DebugMalloc); } static int _PyMem_PymallocEnabled(void) { if (_PyMem_DebugEnabled()) { return (_PyMem_Debug.obj.alloc.malloc == _PyObject_Malloc); } else { return (_PyObject.malloc == _PyObject_Malloc); } } #endif static void _PyMem_SetupDebugHooksDomain(PyMemAllocatorDomain domain) { PyMemAllocatorEx alloc; if (domain == PYMEM_DOMAIN_RAW) { if (_PyMem_Raw.malloc == _PyMem_DebugRawMalloc) { return; } PyMem_GetAllocator(PYMEM_DOMAIN_RAW, &_PyMem_Debug.raw.alloc); alloc.ctx = &_PyMem_Debug.raw; alloc.malloc = _PyMem_DebugRawMalloc; alloc.calloc = _PyMem_DebugRawCalloc; alloc.realloc = _PyMem_DebugRawRealloc; alloc.free = _PyMem_DebugRawFree; PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &alloc); } else if (domain == PYMEM_DOMAIN_MEM) { if (_PyMem.malloc == _PyMem_DebugMalloc) { return; } PyMem_GetAllocator(PYMEM_DOMAIN_MEM, &_PyMem_Debug.mem.alloc); alloc.ctx = &_PyMem_Debug.mem; alloc.malloc = _PyMem_DebugMalloc; alloc.calloc = _PyMem_DebugCalloc; alloc.realloc = _PyMem_DebugRealloc; alloc.free = _PyMem_DebugFree; PyMem_SetAllocator(PYMEM_DOMAIN_MEM, &alloc); } else if (domain == PYMEM_DOMAIN_OBJ) { if (_PyObject.malloc == _PyMem_DebugMalloc) { return; } PyMem_GetAllocator(PYMEM_DOMAIN_OBJ, &_PyMem_Debug.obj.alloc); alloc.ctx = &_PyMem_Debug.obj; alloc.malloc = _PyMem_DebugMalloc; alloc.calloc = _PyMem_DebugCalloc; alloc.realloc = _PyMem_DebugRealloc; alloc.free = _PyMem_DebugFree; PyMem_SetAllocator(PYMEM_DOMAIN_OBJ, &alloc); } } void PyMem_SetupDebugHooks(void) { _PyMem_SetupDebugHooksDomain(PYMEM_DOMAIN_RAW); _PyMem_SetupDebugHooksDomain(PYMEM_DOMAIN_MEM); _PyMem_SetupDebugHooksDomain(PYMEM_DOMAIN_OBJ); } void PyMem_GetAllocator(PyMemAllocatorDomain domain, PyMemAllocatorEx *allocator) { switch(domain) { case PYMEM_DOMAIN_RAW: *allocator = _PyMem_Raw; break; case PYMEM_DOMAIN_MEM: *allocator = _PyMem; break; case PYMEM_DOMAIN_OBJ: *allocator = _PyObject; break; default: /* unknown domain: set all attributes to NULL */ allocator->ctx = NULL; allocator->malloc = NULL; allocator->calloc = NULL; allocator->realloc = NULL; allocator->free = NULL; } } void PyMem_SetAllocator(PyMemAllocatorDomain domain, PyMemAllocatorEx *allocator) { switch(domain) { case PYMEM_DOMAIN_RAW: _PyMem_Raw = *allocator; break; case PYMEM_DOMAIN_MEM: _PyMem = *allocator; break; case PYMEM_DOMAIN_OBJ: _PyObject = *allocator; break; /* ignore unknown domain */ } } void PyObject_GetArenaAllocator(PyObjectArenaAllocator *allocator) { *allocator = _PyObject_Arena; } void * _PyObject_VirtualAlloc(size_t size) { return _PyObject_Arena.alloc(_PyObject_Arena.ctx, size); } void _PyObject_VirtualFree(void *obj, size_t size) { _PyObject_Arena.free(_PyObject_Arena.ctx, obj, size); } void PyObject_SetArenaAllocator(PyObjectArenaAllocator *allocator) { _PyObject_Arena = *allocator; } void * PyMem_RawMalloc(size_t size) { /* * Limit ourselves to PY_SSIZE_T_MAX bytes to prevent security holes. * Most python internals blindly use a signed Py_ssize_t to track * things without checking for overflows or negatives. * As size_t is unsigned, checking for size < 0 is not required. */ if (size > (size_t)PY_SSIZE_T_MAX) return NULL; return _PyMem_Raw.malloc(_PyMem_Raw.ctx, size); } void * PyMem_RawCalloc(size_t nelem, size_t elsize) { /* see PyMem_RawMalloc() */ if (elsize != 0 && nelem > (size_t)PY_SSIZE_T_MAX / elsize) return NULL; return _PyMem_Raw.calloc(_PyMem_Raw.ctx, nelem, elsize); } void* PyMem_RawRealloc(void *ptr, size_t new_size) { /* see PyMem_RawMalloc() */ if (new_size > (size_t)PY_SSIZE_T_MAX) return NULL; return _PyMem_Raw.realloc(_PyMem_Raw.ctx, ptr, new_size); } void PyMem_RawFree(void *ptr) { _PyMem_Raw.free(_PyMem_Raw.ctx, ptr); } void * PyMem_Malloc(size_t size) { /* see PyMem_RawMalloc() */ if (size > (size_t)PY_SSIZE_T_MAX) return NULL; return _PyMem.malloc(_PyMem.ctx, size); } void * PyMem_Calloc(size_t nelem, size_t elsize) { /* see PyMem_RawMalloc() */ if (elsize != 0 && nelem > (size_t)PY_SSIZE_T_MAX / elsize) return NULL; return _PyMem.calloc(_PyMem.ctx, nelem, elsize); } void * PyMem_Realloc(void *ptr, size_t new_size) { /* see PyMem_RawMalloc() */ if (new_size > (size_t)PY_SSIZE_T_MAX) return NULL; return _PyMem.realloc(_PyMem.ctx, ptr, new_size); } void PyMem_Free(void *ptr) { _PyMem.free(_PyMem.ctx, ptr); } wchar_t* _PyMem_RawWcsdup(const wchar_t *str) { assert(str != NULL); size_t len = wcslen(str); if (len > (size_t)PY_SSIZE_T_MAX / sizeof(wchar_t) - 1) { return NULL; } size_t size = (len + 1) * sizeof(wchar_t); wchar_t *str2 = PyMem_RawMalloc(size); if (str2 == NULL) { return NULL; } memcpy(str2, str, size); return str2; } char * _PyMem_RawStrdup(const char *str) { assert(str != NULL); size_t size = strlen(str) + 1; char *copy = PyMem_RawMalloc(size); if (copy == NULL) { return NULL; } memcpy(copy, str, size); return copy; } char * _PyMem_Strdup(const char *str) { assert(str != NULL); size_t size = strlen(str) + 1; char *copy = PyMem_Malloc(size); if (copy == NULL) { return NULL; } memcpy(copy, str, size); return copy; } void * PyObject_Malloc(size_t size) { /* see PyMem_RawMalloc() */ if (size > (size_t)PY_SSIZE_T_MAX) return NULL; return _PyObject.malloc(_PyObject.ctx, size); } void * PyObject_Calloc(size_t nelem, size_t elsize) { /* see PyMem_RawMalloc() */ if (elsize != 0 && nelem > (size_t)PY_SSIZE_T_MAX / elsize) return NULL; return _PyObject.calloc(_PyObject.ctx, nelem, elsize); } void * PyObject_Realloc(void *ptr, size_t new_size) { /* see PyMem_RawMalloc() */ if (new_size > (size_t)PY_SSIZE_T_MAX) return NULL; return _PyObject.realloc(_PyObject.ctx, ptr, new_size); } void PyObject_Free(void *ptr) { _PyObject.free(_PyObject.ctx, ptr); } /* If we're using GCC, use __builtin_expect() to reduce overhead of the valgrind checks */ #if defined(__GNUC__) && (__GNUC__ > 2) && defined(__OPTIMIZE__) # define UNLIKELY(value) __builtin_expect((value), 0) # define LIKELY(value) __builtin_expect((value), 1) #else # define UNLIKELY(value) (value) # define LIKELY(value) (value) #endif #ifdef WITH_PYMALLOC #ifdef WITH_VALGRIND #include /* -1 indicates that we haven't checked that we're running on valgrind yet. */ static int running_on_valgrind = -1; #endif /* An object allocator for Python. Here is an introduction to the layers of the Python memory architecture, showing where the object allocator is actually used (layer +2), It is called for every object allocation and deallocation (PyObject_New/Del), unless the object-specific allocators implement a proprietary allocation scheme (ex.: ints use a simple free list). This is also the place where the cyclic garbage collector operates selectively on container objects. Object-specific allocators _____ ______ ______ ________ [ int ] [ dict ] [ list ] ... [ string ] Python core | +3 | <----- Object-specific memory -----> | <-- Non-object memory --> | _______________________________ | | [ Python's object allocator ] | | +2 | ####### Object memory ####### | <------ Internal buffers ------> | ______________________________________________________________ | [ Python's raw memory allocator (PyMem_ API) ] | +1 | <----- Python memory (under PyMem manager's control) ------> | | __________________________________________________________________ [ Underlying general-purpose allocator (ex: C library malloc) ] 0 | <------ Virtual memory allocated for the python process -------> | ========================================================================= _______________________________________________________________________ [ OS-specific Virtual Memory Manager (VMM) ] -1 | <--- Kernel dynamic storage allocation & management (page-based) ---> | __________________________________ __________________________________ [ ] [ ] -2 | <-- Physical memory: ROM/RAM --> | | <-- Secondary storage (swap) --> | */ /*==========================================================================*/ /* A fast, special-purpose memory allocator for small blocks, to be used on top of a general-purpose malloc -- heavily based on previous art. */ /* Vladimir Marangozov -- August 2000 */ /* * "Memory management is where the rubber meets the road -- if we do the wrong * thing at any level, the results will not be good. And if we don't make the * levels work well together, we are in serious trouble." (1) * * (1) Paul R. Wilson, Mark S. Johnstone, Michael Neely, and David Boles, * "Dynamic Storage Allocation: A Survey and Critical Review", * in Proc. 1995 Int'l. Workshop on Memory Management, September 1995. */ /* #undef WITH_MEMORY_LIMITS */ /* disable mem limit checks */ /*==========================================================================*/ /* * Allocation strategy abstract: * * For small requests, the allocator sub-allocates blocks of memory. * Requests greater than SMALL_REQUEST_THRESHOLD bytes are routed to the * system's allocator. * * Small requests are grouped in size classes spaced 8 bytes apart, due * to the required valid alignment of the returned address. Requests of * a particular size are serviced from memory pools of 4K (one VMM page). * Pools are fragmented on demand and contain free lists of blocks of one * particular size class. In other words, there is a fixed-size allocator * for each size class. Free pools are shared by the different allocators * thus minimizing the space reserved for a particular size class. * * This allocation strategy is a variant of what is known as "simple * segregated storage based on array of free lists". The main drawback of * simple segregated storage is that we might end up with lot of reserved * memory for the different free lists, which degenerate in time. To avoid * this, we partition each free list in pools and we share dynamically the * reserved space between all free lists. This technique is quite efficient * for memory intensive programs which allocate mainly small-sized blocks. * * For small requests we have the following table: * * Request in bytes Size of allocated block Size class idx * ---------------------------------------------------------------- * 1-8 8 0 * 9-16 16 1 * 17-24 24 2 * 25-32 32 3 * 33-40 40 4 * 41-48 48 5 * 49-56 56 6 * 57-64 64 7 * 65-72 72 8 * ... ... ... * 497-504 504 62 * 505-512 512 63 * * 0, SMALL_REQUEST_THRESHOLD + 1 and up: routed to the underlying * allocator. */ /*==========================================================================*/ /* * -- Main tunable settings section -- */ /* * Alignment of addresses returned to the user. 8-bytes alignment works * on most current architectures (with 32-bit or 64-bit address buses). * The alignment value is also used for grouping small requests in size * classes spaced ALIGNMENT bytes apart. * * You shouldn't change this unless you know what you are doing. */ #if SIZEOF_VOID_P > 4 #define ALIGNMENT 16 /* must be 2^N */ #define ALIGNMENT_SHIFT 4 #else #define ALIGNMENT 8 /* must be 2^N */ #define ALIGNMENT_SHIFT 3 #endif /* Return the number of bytes in size class I, as a uint. */ #define INDEX2SIZE(I) (((uint)(I) + 1) << ALIGNMENT_SHIFT) /* * Max size threshold below which malloc requests are considered to be * small enough in order to use preallocated memory pools. You can tune * this value according to your application behaviour and memory needs. * * Note: a size threshold of 512 guarantees that newly created dictionaries * will be allocated from preallocated memory pools on 64-bit. * * The following invariants must hold: * 1) ALIGNMENT <= SMALL_REQUEST_THRESHOLD <= 512 * 2) SMALL_REQUEST_THRESHOLD is evenly divisible by ALIGNMENT * * Although not required, for better performance and space efficiency, * it is recommended that SMALL_REQUEST_THRESHOLD is set to a power of 2. */ #define SMALL_REQUEST_THRESHOLD 512 #define NB_SMALL_SIZE_CLASSES (SMALL_REQUEST_THRESHOLD / ALIGNMENT) /* * The system's VMM page size can be obtained on most unices with a * getpagesize() call or deduced from various header files. To make * things simpler, we assume that it is 4K, which is OK for most systems. * It is probably better if this is the native page size, but it doesn't * have to be. In theory, if SYSTEM_PAGE_SIZE is larger than the native page * size, then `POOL_ADDR(p)->arenaindex' could rarely cause a segmentation * violation fault. 4K is apparently OK for all the platforms that python * currently targets. */ #define SYSTEM_PAGE_SIZE (4 * 1024) #define SYSTEM_PAGE_SIZE_MASK (SYSTEM_PAGE_SIZE - 1) /* * Maximum amount of memory managed by the allocator for small requests. */ #ifdef WITH_MEMORY_LIMITS #ifndef SMALL_MEMORY_LIMIT #define SMALL_MEMORY_LIMIT (64 * 1024 * 1024) /* 64 MB -- more? */ #endif #endif #if !defined(WITH_PYMALLOC_RADIX_TREE) /* Use radix-tree to track arena memory regions, for address_in_range(). * Enable by default since it allows larger pool sizes. Can be disabled * using -DWITH_PYMALLOC_RADIX_TREE=0 */ #define WITH_PYMALLOC_RADIX_TREE 1 #endif #if SIZEOF_VOID_P > 4 /* on 64-bit platforms use larger pools and arenas if we can */ #define USE_LARGE_ARENAS #if WITH_PYMALLOC_RADIX_TREE /* large pools only supported if radix-tree is enabled */ #define USE_LARGE_POOLS #endif #endif /* * The allocator sub-allocates blocks of memory (called arenas) aligned * on a page boundary. This is a reserved virtual address space for the * current process (obtained through a malloc()/mmap() call). In no way this * means that the memory arenas will be used entirely. A malloc() is * usually an address range reservation for bytes, unless all pages within * this space are referenced subsequently. So malloc'ing big blocks and not * using them does not mean "wasting memory". It's an addressable range * wastage... * * Arenas are allocated with mmap() on systems supporting anonymous memory * mappings to reduce heap fragmentation. */ #ifdef USE_LARGE_ARENAS #define ARENA_BITS 20 /* 1 MiB */ #else #define ARENA_BITS 18 /* 256 KiB */ #endif #define ARENA_SIZE (1 << ARENA_BITS) #define ARENA_SIZE_MASK (ARENA_SIZE - 1) #ifdef WITH_MEMORY_LIMITS #define MAX_ARENAS (SMALL_MEMORY_LIMIT / ARENA_SIZE) #endif /* * Size of the pools used for small blocks. Must be a power of 2. */ #ifdef USE_LARGE_POOLS #define POOL_BITS 14 /* 16 KiB */ #else #define POOL_BITS 12 /* 4 KiB */ #endif #define POOL_SIZE (1 << POOL_BITS) #define POOL_SIZE_MASK (POOL_SIZE - 1) #if !WITH_PYMALLOC_RADIX_TREE #if POOL_SIZE != SYSTEM_PAGE_SIZE # error "pool size must be equal to system page size" #endif #endif #define MAX_POOLS_IN_ARENA (ARENA_SIZE / POOL_SIZE) #if MAX_POOLS_IN_ARENA * POOL_SIZE != ARENA_SIZE # error "arena size not an exact multiple of pool size" #endif /* * -- End of tunable settings section -- */ /*==========================================================================*/ /* When you say memory, my mind reasons in terms of (pointers to) blocks */ typedef uint8_t block; /* Pool for small blocks. */ struct pool_header { union { block *_padding; uint count; } ref; /* number of allocated blocks */ block *freeblock; /* pool's free list head */ struct pool_header *nextpool; /* next pool of this size class */ struct pool_header *prevpool; /* previous pool "" */ uint arenaindex; /* index into arenas of base adr */ uint szidx; /* block size class index */ uint nextoffset; /* bytes to virgin block */ uint maxnextoffset; /* largest valid nextoffset */ }; typedef struct pool_header *poolp; /* Record keeping for arenas. */ struct arena_object { /* The address of the arena, as returned by malloc. Note that 0 * will never be returned by a successful malloc, and is used * here to mark an arena_object that doesn't correspond to an * allocated arena. */ uintptr_t address; /* Pool-aligned pointer to the next pool to be carved off. */ block* pool_address; /* The number of available pools in the arena: free pools + never- * allocated pools. */ uint nfreepools; /* The total number of pools in the arena, whether or not available. */ uint ntotalpools; /* Singly-linked list of available pools. */ struct pool_header* freepools; /* Whenever this arena_object is not associated with an allocated * arena, the nextarena member is used to link all unassociated * arena_objects in the singly-linked `unused_arena_objects` list. * The prevarena member is unused in this case. * * When this arena_object is associated with an allocated arena * with at least one available pool, both members are used in the * doubly-linked `usable_arenas` list, which is maintained in * increasing order of `nfreepools` values. * * Else this arena_object is associated with an allocated arena * all of whose pools are in use. `nextarena` and `prevarena` * are both meaningless in this case. */ struct arena_object* nextarena; struct arena_object* prevarena; }; #define POOL_OVERHEAD _Py_SIZE_ROUND_UP(sizeof(struct pool_header), ALIGNMENT) #define DUMMY_SIZE_IDX 0xffff /* size class of newly cached pools */ /* Round pointer P down to the closest pool-aligned address <= P, as a poolp */ #define POOL_ADDR(P) ((poolp)_Py_ALIGN_DOWN((P), POOL_SIZE)) /* Return total number of blocks in pool of size index I, as a uint. */ #define NUMBLOCKS(I) ((uint)(POOL_SIZE - POOL_OVERHEAD) / INDEX2SIZE(I)) /*==========================================================================*/ /* * Pool table -- headed, circular, doubly-linked lists of partially used pools. This is involved. For an index i, usedpools[i+i] is the header for a list of all partially used pools holding small blocks with "size class idx" i. So usedpools[0] corresponds to blocks of size 8, usedpools[2] to blocks of size 16, and so on: index 2*i <-> blocks of size (i+1)<freeblock points to the start of a singly-linked list of free blocks within the pool. When a block is freed, it's inserted at the front of its pool's freeblock list. Note that the available blocks in a pool are *not* linked all together when a pool is initialized. Instead only "the first two" (lowest addresses) blocks are set up, returning the first such block, and setting pool->freeblock to a one-block list holding the second such block. This is consistent with that pymalloc strives at all levels (arena, pool, and block) never to touch a piece of memory until it's actually needed. So long as a pool is in the used state, we're certain there *is* a block available for allocating, and pool->freeblock is not NULL. If pool->freeblock points to the end of the free list before we've carved the entire pool into blocks, that means we simply haven't yet gotten to one of the higher-address blocks. The offset from the pool_header to the start of "the next" virgin block is stored in the pool_header nextoffset member, and the largest value of nextoffset that makes sense is stored in the maxnextoffset member when a pool is initialized. All the blocks in a pool have been passed out at least once when and only when nextoffset > maxnextoffset. Major obscurity: While the usedpools vector is declared to have poolp entries, it doesn't really. It really contains two pointers per (conceptual) poolp entry, the nextpool and prevpool members of a pool_header. The excruciating initialization code below fools C so that usedpool[i+i] "acts like" a genuine poolp, but only so long as you only reference its nextpool and prevpool members. The "- 2*sizeof(block *)" gibberish is compensating for that a pool_header's nextpool and prevpool members immediately follow a pool_header's first two members: union { block *_padding; uint count; } ref; block *freeblock; each of which consume sizeof(block *) bytes. So what usedpools[i+i] really contains is a fudged-up pointer p such that *if* C believes it's a poolp pointer, then p->nextpool and p->prevpool are both p (meaning that the headed circular list is empty). It's unclear why the usedpools setup is so convoluted. It could be to minimize the amount of cache required to hold this heavily-referenced table (which only *needs* the two interpool pointer members of a pool_header). OTOH, referencing code has to remember to "double the index" and doing so isn't free, usedpools[0] isn't a strictly legal pointer, and we're crucially relying on that C doesn't insert any padding anywhere in a pool_header at or before the prevpool member. **************************************************************************** */ #define PTA(x) ((poolp )((uint8_t *)&(usedpools[2*(x)]) - 2*sizeof(block *))) #define PT(x) PTA(x), PTA(x) static poolp usedpools[2 * ((NB_SMALL_SIZE_CLASSES + 7) / 8) * 8] = { PT(0), PT(1), PT(2), PT(3), PT(4), PT(5), PT(6), PT(7) #if NB_SMALL_SIZE_CLASSES > 8 , PT(8), PT(9), PT(10), PT(11), PT(12), PT(13), PT(14), PT(15) #if NB_SMALL_SIZE_CLASSES > 16 , PT(16), PT(17), PT(18), PT(19), PT(20), PT(21), PT(22), PT(23) #if NB_SMALL_SIZE_CLASSES > 24 , PT(24), PT(25), PT(26), PT(27), PT(28), PT(29), PT(30), PT(31) #if NB_SMALL_SIZE_CLASSES > 32 , PT(32), PT(33), PT(34), PT(35), PT(36), PT(37), PT(38), PT(39) #if NB_SMALL_SIZE_CLASSES > 40 , PT(40), PT(41), PT(42), PT(43), PT(44), PT(45), PT(46), PT(47) #if NB_SMALL_SIZE_CLASSES > 48 , PT(48), PT(49), PT(50), PT(51), PT(52), PT(53), PT(54), PT(55) #if NB_SMALL_SIZE_CLASSES > 56 , PT(56), PT(57), PT(58), PT(59), PT(60), PT(61), PT(62), PT(63) #if NB_SMALL_SIZE_CLASSES > 64 #error "NB_SMALL_SIZE_CLASSES should be less than 64" #endif /* NB_SMALL_SIZE_CLASSES > 64 */ #endif /* NB_SMALL_SIZE_CLASSES > 56 */ #endif /* NB_SMALL_SIZE_CLASSES > 48 */ #endif /* NB_SMALL_SIZE_CLASSES > 40 */ #endif /* NB_SMALL_SIZE_CLASSES > 32 */ #endif /* NB_SMALL_SIZE_CLASSES > 24 */ #endif /* NB_SMALL_SIZE_CLASSES > 16 */ #endif /* NB_SMALL_SIZE_CLASSES > 8 */ }; /*========================================================================== Arena management. `arenas` is a vector of arena_objects. It contains maxarenas entries, some of which may not be currently used (== they're arena_objects that aren't currently associated with an allocated arena). Note that arenas proper are separately malloc'ed. Prior to Python 2.5, arenas were never free()'ed. Starting with Python 2.5, we do try to free() arenas, and use some mild heuristic strategies to increase the likelihood that arenas eventually can be freed. unused_arena_objects This is a singly-linked list of the arena_objects that are currently not being used (no arena is associated with them). Objects are taken off the head of the list in new_arena(), and are pushed on the head of the list in PyObject_Free() when the arena is empty. Key invariant: an arena_object is on this list if and only if its .address member is 0. usable_arenas This is a doubly-linked list of the arena_objects associated with arenas that have pools available. These pools are either waiting to be reused, or have not been used before. The list is sorted to have the most- allocated arenas first (ascending order based on the nfreepools member). This means that the next allocation will come from a heavily used arena, which gives the nearly empty arenas a chance to be returned to the system. In my unscientific tests this dramatically improved the number of arenas that could be freed. Note that an arena_object associated with an arena all of whose pools are currently in use isn't on either list. Changed in Python 3.8: keeping usable_arenas sorted by number of free pools used to be done by one-at-a-time linear search when an arena's number of free pools changed. That could, overall, consume time quadratic in the number of arenas. That didn't really matter when there were only a few hundred arenas (typical!), but could be a timing disaster when there were hundreds of thousands. See bpo-37029. Now we have a vector of "search fingers" to eliminate the need to search: nfp2lasta[nfp] returns the last ("rightmost") arena in usable_arenas with nfp free pools. This is NULL if and only if there is no arena with nfp free pools in usable_arenas. */ /* Array of objects used to track chunks of memory (arenas). */ static struct arena_object* arenas = NULL; /* Number of slots currently allocated in the `arenas` vector. */ static uint maxarenas = 0; /* The head of the singly-linked, NULL-terminated list of available * arena_objects. */ static struct arena_object* unused_arena_objects = NULL; /* The head of the doubly-linked, NULL-terminated at each end, list of * arena_objects associated with arenas that have pools available. */ static struct arena_object* usable_arenas = NULL; /* nfp2lasta[nfp] is the last arena in usable_arenas with nfp free pools */ static struct arena_object* nfp2lasta[MAX_POOLS_IN_ARENA + 1] = { NULL }; /* How many arena_objects do we initially allocate? * 16 = can allocate 16 arenas = 16 * ARENA_SIZE = 4MB before growing the * `arenas` vector. */ #define INITIAL_ARENA_OBJECTS 16 /* Number of arenas allocated that haven't been free()'d. */ static size_t narenas_currently_allocated = 0; /* Total number of times malloc() called to allocate an arena. */ static size_t ntimes_arena_allocated = 0; /* High water mark (max value ever seen) for narenas_currently_allocated. */ static size_t narenas_highwater = 0; static Py_ssize_t raw_allocated_blocks; Py_ssize_t _Py_GetAllocatedBlocks(void) { Py_ssize_t n = raw_allocated_blocks; /* add up allocated blocks for used pools */ for (uint i = 0; i < maxarenas; ++i) { /* Skip arenas which are not allocated. */ if (arenas[i].address == 0) { continue; } uintptr_t base = (uintptr_t)_Py_ALIGN_UP(arenas[i].address, POOL_SIZE); /* visit every pool in the arena */ assert(base <= (uintptr_t) arenas[i].pool_address); for (; base < (uintptr_t) arenas[i].pool_address; base += POOL_SIZE) { poolp p = (poolp)base; n += p->ref.count; } } return n; } #if WITH_PYMALLOC_RADIX_TREE /*==========================================================================*/ /* radix tree for tracking arena usage. If enabled, used to implement address_in_range(). memory address bit allocation for keys 64-bit pointers, IGNORE_BITS=0 and 2^20 arena size: 15 -> MAP_TOP_BITS 15 -> MAP_MID_BITS 14 -> MAP_BOT_BITS 20 -> ideal aligned arena ---- 64 64-bit pointers, IGNORE_BITS=16, and 2^20 arena size: 16 -> IGNORE_BITS 10 -> MAP_TOP_BITS 10 -> MAP_MID_BITS 8 -> MAP_BOT_BITS 20 -> ideal aligned arena ---- 64 32-bit pointers and 2^18 arena size: 14 -> MAP_BOT_BITS 18 -> ideal aligned arena ---- 32 */ #if SIZEOF_VOID_P == 8 /* number of bits in a pointer */ #define POINTER_BITS 64 /* High bits of memory addresses that will be ignored when indexing into the * radix tree. Setting this to zero is the safe default. For most 64-bit * machines, setting this to 16 would be safe. The kernel would not give * user-space virtual memory addresses that have significant information in * those high bits. The main advantage to setting IGNORE_BITS > 0 is that less * virtual memory will be used for the top and middle radix tree arrays. Those * arrays are allocated in the BSS segment and so will typically consume real * memory only if actually accessed. */ #define IGNORE_BITS 0 /* use the top and mid layers of the radix tree */ #define USE_INTERIOR_NODES #elif SIZEOF_VOID_P == 4 #define POINTER_BITS 32 #define IGNORE_BITS 0 #else /* Currently this code works for 64-bit or 32-bit pointers only. */ #error "obmalloc radix tree requires 64-bit or 32-bit pointers." #endif /* SIZEOF_VOID_P */ /* arena_coverage_t members require this to be true */ #if ARENA_BITS >= 32 # error "arena size must be < 2^32" #endif /* the lower bits of the address that are not ignored */ #define ADDRESS_BITS (POINTER_BITS - IGNORE_BITS) #ifdef USE_INTERIOR_NODES /* number of bits used for MAP_TOP and MAP_MID nodes */ #define INTERIOR_BITS ((ADDRESS_BITS - ARENA_BITS + 2) / 3) #else #define INTERIOR_BITS 0 #endif #define MAP_TOP_BITS INTERIOR_BITS #define MAP_TOP_LENGTH (1 << MAP_TOP_BITS) #define MAP_TOP_MASK (MAP_TOP_LENGTH - 1) #define MAP_MID_BITS INTERIOR_BITS #define MAP_MID_LENGTH (1 << MAP_MID_BITS) #define MAP_MID_MASK (MAP_MID_LENGTH - 1) #define MAP_BOT_BITS (ADDRESS_BITS - ARENA_BITS - 2*INTERIOR_BITS) #define MAP_BOT_LENGTH (1 << MAP_BOT_BITS) #define MAP_BOT_MASK (MAP_BOT_LENGTH - 1) #define MAP_BOT_SHIFT ARENA_BITS #define MAP_MID_SHIFT (MAP_BOT_BITS + MAP_BOT_SHIFT) #define MAP_TOP_SHIFT (MAP_MID_BITS + MAP_MID_SHIFT) #define AS_UINT(p) ((uintptr_t)(p)) #define MAP_BOT_INDEX(p) ((AS_UINT(p) >> MAP_BOT_SHIFT) & MAP_BOT_MASK) #define MAP_MID_INDEX(p) ((AS_UINT(p) >> MAP_MID_SHIFT) & MAP_MID_MASK) #define MAP_TOP_INDEX(p) ((AS_UINT(p) >> MAP_TOP_SHIFT) & MAP_TOP_MASK) #if IGNORE_BITS > 0 /* Return the ignored part of the pointer address. Those bits should be same * for all valid pointers if IGNORE_BITS is set correctly. */ #define HIGH_BITS(p) (AS_UINT(p) >> ADDRESS_BITS) #else #define HIGH_BITS(p) 0 #endif /* This is the leaf of the radix tree. See arena_map_mark_used() for the * meaning of these members. */ typedef struct { int32_t tail_hi; int32_t tail_lo; } arena_coverage_t; typedef struct arena_map_bot { /* The members tail_hi and tail_lo are accessed together. So, it * better to have them as an array of structs, rather than two * arrays. */ arena_coverage_t arenas[MAP_BOT_LENGTH]; } arena_map_bot_t; #ifdef USE_INTERIOR_NODES typedef struct arena_map_mid { struct arena_map_bot *ptrs[MAP_MID_LENGTH]; } arena_map_mid_t; typedef struct arena_map_top { struct arena_map_mid *ptrs[MAP_TOP_LENGTH]; } arena_map_top_t; #endif /* The root of radix tree. Note that by initializing like this, the memory * should be in the BSS. The OS will only memory map pages as the MAP_MID * nodes get used (OS pages are demand loaded as needed). */ #ifdef USE_INTERIOR_NODES static arena_map_top_t arena_map_root; /* accounting for number of used interior nodes */ static int arena_map_mid_count; static int arena_map_bot_count; #else static arena_map_bot_t arena_map_root; #endif /* Return a pointer to a bottom tree node, return NULL if it doesn't exist or * it cannot be created */ static arena_map_bot_t * arena_map_get(block *p, int create) { #ifdef USE_INTERIOR_NODES /* sanity check that IGNORE_BITS is correct */ assert(HIGH_BITS(p) == HIGH_BITS(&arena_map_root)); int i1 = MAP_TOP_INDEX(p); if (arena_map_root.ptrs[i1] == NULL) { if (!create) { return NULL; } arena_map_mid_t *n = PyMem_RawCalloc(1, sizeof(arena_map_mid_t)); if (n == NULL) { return NULL; } arena_map_root.ptrs[i1] = n; arena_map_mid_count++; } int i2 = MAP_MID_INDEX(p); if (arena_map_root.ptrs[i1]->ptrs[i2] == NULL) { if (!create) { return NULL; } arena_map_bot_t *n = PyMem_RawCalloc(1, sizeof(arena_map_bot_t)); if (n == NULL) { return NULL; } arena_map_root.ptrs[i1]->ptrs[i2] = n; arena_map_bot_count++; } return arena_map_root.ptrs[i1]->ptrs[i2]; #else return &arena_map_root; #endif } /* The radix tree only tracks arenas. So, for 16 MiB arenas, we throw * away 24 bits of the address. That reduces the space requirement of * the tree compared to similar radix tree page-map schemes. In * exchange for slashing the space requirement, it needs more * computation to check an address. * * Tracking coverage is done by "ideal" arena address. It is easier to * explain in decimal so let's say that the arena size is 100 bytes. * Then, ideal addresses are 100, 200, 300, etc. For checking if a * pointer address is inside an actual arena, we have to check two ideal * arena addresses. E.g. if pointer is 357, we need to check 200 and * 300. In the rare case that an arena is aligned in the ideal way * (e.g. base address of arena is 200) then we only have to check one * ideal address. * * The tree nodes for 200 and 300 both store the address of arena. * There are two cases: the arena starts at a lower ideal arena and * extends to this one, or the arena starts in this arena and extends to * the next ideal arena. The tail_lo and tail_hi members correspond to * these two cases. */ /* mark or unmark addresses covered by arena */ static int arena_map_mark_used(uintptr_t arena_base, int is_used) { /* sanity check that IGNORE_BITS is correct */ assert(HIGH_BITS(arena_base) == HIGH_BITS(&arena_map_root)); arena_map_bot_t *n_hi = arena_map_get((block *)arena_base, is_used); if (n_hi == NULL) { assert(is_used); /* otherwise node should already exist */ return 0; /* failed to allocate space for node */ } int i3 = MAP_BOT_INDEX((block *)arena_base); int32_t tail = (int32_t)(arena_base & ARENA_SIZE_MASK); if (tail == 0) { /* is ideal arena address */ n_hi->arenas[i3].tail_hi = is_used ? -1 : 0; } else { /* arena_base address is not ideal (aligned to arena size) and * so it potentially covers two MAP_BOT nodes. Get the MAP_BOT node * for the next arena. Note that it might be in different MAP_TOP * and MAP_MID nodes as well so we need to call arena_map_get() * again (do the full tree traversal). */ n_hi->arenas[i3].tail_hi = is_used ? tail : 0; uintptr_t arena_base_next = arena_base + ARENA_SIZE; /* If arena_base is a legit arena address, so is arena_base_next - 1 * (last address in arena). If arena_base_next overflows then it * must overflow to 0. However, that would mean arena_base was * "ideal" and we should not be in this case. */ assert(arena_base < arena_base_next); arena_map_bot_t *n_lo = arena_map_get((block *)arena_base_next, is_used); if (n_lo == NULL) { assert(is_used); /* otherwise should already exist */ n_hi->arenas[i3].tail_hi = 0; return 0; /* failed to allocate space for node */ } int i3_next = MAP_BOT_INDEX(arena_base_next); n_lo->arenas[i3_next].tail_lo = is_used ? tail : 0; } return 1; } /* Return true if 'p' is a pointer inside an obmalloc arena. * _PyObject_Free() calls this so it needs to be very fast. */ static int arena_map_is_used(block *p) { arena_map_bot_t *n = arena_map_get(p, 0); if (n == NULL) { return 0; } int i3 = MAP_BOT_INDEX(p); /* ARENA_BITS must be < 32 so that the tail is a non-negative int32_t. */ int32_t hi = n->arenas[i3].tail_hi; int32_t lo = n->arenas[i3].tail_lo; int32_t tail = (int32_t)(AS_UINT(p) & ARENA_SIZE_MASK); return (tail < lo) || (tail >= hi && hi != 0); } /* end of radix tree logic */ /*==========================================================================*/ #endif /* WITH_PYMALLOC_RADIX_TREE */ /* Allocate a new arena. If we run out of memory, return NULL. Else * allocate a new arena, and return the address of an arena_object * describing the new arena. It's expected that the caller will set * `usable_arenas` to the return value. */ static struct arena_object* new_arena(void) { struct arena_object* arenaobj; uint excess; /* number of bytes above pool alignment */ void *address; static int debug_stats = -1; if (debug_stats == -1) { const char *opt = Py_GETENV("PYTHONMALLOCSTATS"); debug_stats = (opt != NULL && *opt != '\0'); } if (debug_stats) { _PyObject_DebugMallocStats(stderr); } if (unused_arena_objects == NULL) { uint i; uint numarenas; size_t nbytes; /* Double the number of arena objects on each allocation. * Note that it's possible for `numarenas` to overflow. */ numarenas = maxarenas ? maxarenas << 1 : INITIAL_ARENA_OBJECTS; if (numarenas <= maxarenas) return NULL; /* overflow */ #if SIZEOF_SIZE_T <= SIZEOF_INT if (numarenas > SIZE_MAX / sizeof(*arenas)) return NULL; /* overflow */ #endif nbytes = numarenas * sizeof(*arenas); arenaobj = (struct arena_object *)PyMem_RawRealloc(arenas, nbytes); if (arenaobj == NULL) return NULL; arenas = arenaobj; /* We might need to fix pointers that were copied. However, * new_arena only gets called when all the pages in the * previous arenas are full. Thus, there are *no* pointers * into the old array. Thus, we don't have to worry about * invalid pointers. Just to be sure, some asserts: */ assert(usable_arenas == NULL); assert(unused_arena_objects == NULL); /* Put the new arenas on the unused_arena_objects list. */ for (i = maxarenas; i < numarenas; ++i) { arenas[i].address = 0; /* mark as unassociated */ arenas[i].nextarena = i < numarenas - 1 ? &arenas[i+1] : NULL; } /* Update globals. */ unused_arena_objects = &arenas[maxarenas]; maxarenas = numarenas; } /* Take the next available arena object off the head of the list. */ assert(unused_arena_objects != NULL); arenaobj = unused_arena_objects; unused_arena_objects = arenaobj->nextarena; assert(arenaobj->address == 0); address = _PyObject_Arena.alloc(_PyObject_Arena.ctx, ARENA_SIZE); #if WITH_PYMALLOC_RADIX_TREE if (address != NULL) { if (!arena_map_mark_used((uintptr_t)address, 1)) { /* marking arena in radix tree failed, abort */ _PyObject_Arena.free(_PyObject_Arena.ctx, address, ARENA_SIZE); address = NULL; } } #endif if (address == NULL) { /* The allocation failed: return NULL after putting the * arenaobj back. */ arenaobj->nextarena = unused_arena_objects; unused_arena_objects = arenaobj; return NULL; } arenaobj->address = (uintptr_t)address; ++narenas_currently_allocated; ++ntimes_arena_allocated; if (narenas_currently_allocated > narenas_highwater) narenas_highwater = narenas_currently_allocated; arenaobj->freepools = NULL; /* pool_address <- first pool-aligned address in the arena nfreepools <- number of whole pools that fit after alignment */ arenaobj->pool_address = (block*)arenaobj->address; arenaobj->nfreepools = MAX_POOLS_IN_ARENA; excess = (uint)(arenaobj->address & POOL_SIZE_MASK); if (excess != 0) { --arenaobj->nfreepools; arenaobj->pool_address += POOL_SIZE - excess; } arenaobj->ntotalpools = arenaobj->nfreepools; return arenaobj; } #if WITH_PYMALLOC_RADIX_TREE /* Return true if and only if P is an address that was allocated by pymalloc. When the radix tree is used, 'poolp' is unused. */ static bool address_in_range(void *p, poolp pool) { return arena_map_is_used(p); } #else /* address_in_range(P, POOL) Return true if and only if P is an address that was allocated by pymalloc. POOL must be the pool address associated with P, i.e., POOL = POOL_ADDR(P) (the caller is asked to compute this because the macro expands POOL more than once, and for efficiency it's best for the caller to assign POOL_ADDR(P) to a variable and pass the latter to the macro; because address_in_range is called on every alloc/realloc/free, micro-efficiency is important here). Tricky: Let B be the arena base address associated with the pool, B = arenas[(POOL)->arenaindex].address. Then P belongs to the arena if and only if B <= P < B + ARENA_SIZE Subtracting B throughout, this is true iff 0 <= P-B < ARENA_SIZE By using unsigned arithmetic, the "0 <=" half of the test can be skipped. Obscure: A PyMem "free memory" function can call the pymalloc free or realloc before the first arena has been allocated. `arenas` is still NULL in that case. We're relying on that maxarenas is also 0 in that case, so that (POOL)->arenaindex < maxarenas must be false, saving us from trying to index into a NULL arenas. Details: given P and POOL, the arena_object corresponding to P is AO = arenas[(POOL)->arenaindex]. Suppose obmalloc controls P. Then (barring wild stores, etc), POOL is the correct address of P's pool, AO.address is the correct base address of the pool's arena, and P must be within ARENA_SIZE of AO.address. In addition, AO.address is not 0 (no arena can start at address 0 (NULL)). Therefore address_in_range correctly reports that obmalloc controls P. Now suppose obmalloc does not control P (e.g., P was obtained via a direct call to the system malloc() or realloc()). (POOL)->arenaindex may be anything in this case -- it may even be uninitialized trash. If the trash arenaindex is >= maxarenas, the macro correctly concludes at once that obmalloc doesn't control P. Else arenaindex is < maxarena, and AO is read up. If AO corresponds to an allocated arena, obmalloc controls all the memory in slice AO.address : AO.address+ARENA_SIZE. By case assumption, P is not controlled by obmalloc, so P doesn't lie in that slice, so the macro correctly reports that P is not controlled by obmalloc. Finally, if P is not controlled by obmalloc and AO corresponds to an unused arena_object (one not currently associated with an allocated arena), AO.address is 0, and the second test in the macro reduces to: P < ARENA_SIZE If P >= ARENA_SIZE (extremely likely), the macro again correctly concludes that P is not controlled by obmalloc. However, if P < ARENA_SIZE, this part of the test still passes, and the third clause (AO.address != 0) is necessary to get the correct result: AO.address is 0 in this case, so the macro correctly reports that P is not controlled by obmalloc (despite that P lies in slice AO.address : AO.address + ARENA_SIZE). Note: The third (AO.address != 0) clause was added in Python 2.5. Before 2.5, arenas were never free()'ed, and an arenaindex < maxarena always corresponded to a currently-allocated arena, so the "P is not controlled by obmalloc, AO corresponds to an unused arena_object, and P < ARENA_SIZE" case was impossible. Note that the logic is excruciating, and reading up possibly uninitialized memory when P is not controlled by obmalloc (to get at (POOL)->arenaindex) creates problems for some memory debuggers. The overwhelming advantage is that this test determines whether an arbitrary address is controlled by obmalloc in a small constant time, independent of the number of arenas obmalloc controls. Since this test is needed at every entry point, it's extremely desirable that it be this fast. */ static bool _Py_NO_SANITIZE_ADDRESS _Py_NO_SANITIZE_THREAD _Py_NO_SANITIZE_MEMORY address_in_range(void *p, poolp pool) { // Since address_in_range may be reading from memory which was not allocated // by Python, it is important that pool->arenaindex is read only once, as // another thread may be concurrently modifying the value without holding // the GIL. The following dance forces the compiler to read pool->arenaindex // only once. uint arenaindex = *((volatile uint *)&pool->arenaindex); return arenaindex < maxarenas && (uintptr_t)p - arenas[arenaindex].address < ARENA_SIZE && arenas[arenaindex].address != 0; } #endif /* !WITH_PYMALLOC_RADIX_TREE */ /*==========================================================================*/ // Called when freelist is exhausted. Extend the freelist if there is // space for a block. Otherwise, remove this pool from usedpools. static void pymalloc_pool_extend(poolp pool, uint size) { if (UNLIKELY(pool->nextoffset <= pool->maxnextoffset)) { /* There is room for another block. */ pool->freeblock = (block*)pool + pool->nextoffset; pool->nextoffset += INDEX2SIZE(size); *(block **)(pool->freeblock) = NULL; return; } /* Pool is full, unlink from used pools. */ poolp next; next = pool->nextpool; pool = pool->prevpool; next->prevpool = pool; pool->nextpool = next; } /* called when pymalloc_alloc can not allocate a block from usedpool. * This function takes new pool and allocate a block from it. */ static void* allocate_from_new_pool(uint size) { /* There isn't a pool of the right size class immediately * available: use a free pool. */ if (UNLIKELY(usable_arenas == NULL)) { /* No arena has a free pool: allocate a new arena. */ #ifdef WITH_MEMORY_LIMITS if (narenas_currently_allocated >= MAX_ARENAS) { return NULL; } #endif usable_arenas = new_arena(); if (usable_arenas == NULL) { return NULL; } usable_arenas->nextarena = usable_arenas->prevarena = NULL; assert(nfp2lasta[usable_arenas->nfreepools] == NULL); nfp2lasta[usable_arenas->nfreepools] = usable_arenas; } assert(usable_arenas->address != 0); /* This arena already had the smallest nfreepools value, so decreasing * nfreepools doesn't change that, and we don't need to rearrange the * usable_arenas list. However, if the arena becomes wholly allocated, * we need to remove its arena_object from usable_arenas. */ assert(usable_arenas->nfreepools > 0); if (nfp2lasta[usable_arenas->nfreepools] == usable_arenas) { /* It's the last of this size, so there won't be any. */ nfp2lasta[usable_arenas->nfreepools] = NULL; } /* If any free pools will remain, it will be the new smallest. */ if (usable_arenas->nfreepools > 1) { assert(nfp2lasta[usable_arenas->nfreepools - 1] == NULL); nfp2lasta[usable_arenas->nfreepools - 1] = usable_arenas; } /* Try to get a cached free pool. */ poolp pool = usable_arenas->freepools; if (LIKELY(pool != NULL)) { /* Unlink from cached pools. */ usable_arenas->freepools = pool->nextpool; usable_arenas->nfreepools--; if (UNLIKELY(usable_arenas->nfreepools == 0)) { /* Wholly allocated: remove. */ assert(usable_arenas->freepools == NULL); assert(usable_arenas->nextarena == NULL || usable_arenas->nextarena->prevarena == usable_arenas); usable_arenas = usable_arenas->nextarena; if (usable_arenas != NULL) { usable_arenas->prevarena = NULL; assert(usable_arenas->address != 0); } } else { /* nfreepools > 0: it must be that freepools * isn't NULL, or that we haven't yet carved * off all the arena's pools for the first * time. */ assert(usable_arenas->freepools != NULL || usable_arenas->pool_address <= (block*)usable_arenas->address + ARENA_SIZE - POOL_SIZE); } } else { /* Carve off a new pool. */ assert(usable_arenas->nfreepools > 0); assert(usable_arenas->freepools == NULL); pool = (poolp)usable_arenas->pool_address; assert((block*)pool <= (block*)usable_arenas->address + ARENA_SIZE - POOL_SIZE); pool->arenaindex = (uint)(usable_arenas - arenas); assert(&arenas[pool->arenaindex] == usable_arenas); pool->szidx = DUMMY_SIZE_IDX; usable_arenas->pool_address += POOL_SIZE; --usable_arenas->nfreepools; if (usable_arenas->nfreepools == 0) { assert(usable_arenas->nextarena == NULL || usable_arenas->nextarena->prevarena == usable_arenas); /* Unlink the arena: it is completely allocated. */ usable_arenas = usable_arenas->nextarena; if (usable_arenas != NULL) { usable_arenas->prevarena = NULL; assert(usable_arenas->address != 0); } } } /* Frontlink to used pools. */ block *bp; poolp next = usedpools[size + size]; /* == prev */ pool->nextpool = next; pool->prevpool = next; next->nextpool = pool; next->prevpool = pool; pool->ref.count = 1; if (pool->szidx == size) { /* Luckily, this pool last contained blocks * of the same size class, so its header * and free list are already initialized. */ bp = pool->freeblock; assert(bp != NULL); pool->freeblock = *(block **)bp; return bp; } /* * Initialize the pool header, set up the free list to * contain just the second block, and return the first * block. */ pool->szidx = size; size = INDEX2SIZE(size); bp = (block *)pool + POOL_OVERHEAD; pool->nextoffset = POOL_OVERHEAD + (size << 1); pool->maxnextoffset = POOL_SIZE - size; pool->freeblock = bp + size; *(block **)(pool->freeblock) = NULL; return bp; } /* pymalloc allocator Return a pointer to newly allocated memory if pymalloc allocated memory. Return NULL if pymalloc failed to allocate the memory block: on bigger requests, on error in the code below (as a last chance to serve the request) or when the max memory limit has been reached. */ static inline void* pymalloc_alloc(void *ctx, size_t nbytes) { #ifdef WITH_VALGRIND if (UNLIKELY(running_on_valgrind == -1)) { running_on_valgrind = RUNNING_ON_VALGRIND; } if (UNLIKELY(running_on_valgrind)) { return NULL; } #endif if (UNLIKELY(nbytes == 0)) { return NULL; } if (UNLIKELY(nbytes > SMALL_REQUEST_THRESHOLD)) { return NULL; } uint size = (uint)(nbytes - 1) >> ALIGNMENT_SHIFT; poolp pool = usedpools[size + size]; block *bp; if (LIKELY(pool != pool->nextpool)) { /* * There is a used pool for this size class. * Pick up the head block of its free list. */ ++pool->ref.count; bp = pool->freeblock; assert(bp != NULL); if (UNLIKELY((pool->freeblock = *(block **)bp) == NULL)) { // Reached the end of the free list, try to extend it. pymalloc_pool_extend(pool, size); } } else { /* There isn't a pool of the right size class immediately * available: use a free pool. */ bp = allocate_from_new_pool(size); } return (void *)bp; } static void * _PyObject_Malloc(void *ctx, size_t nbytes) { void* ptr = pymalloc_alloc(ctx, nbytes); if (LIKELY(ptr != NULL)) { return ptr; } ptr = PyMem_RawMalloc(nbytes); if (ptr != NULL) { raw_allocated_blocks++; } return ptr; } static void * _PyObject_Calloc(void *ctx, size_t nelem, size_t elsize) { assert(elsize == 0 || nelem <= (size_t)PY_SSIZE_T_MAX / elsize); size_t nbytes = nelem * elsize; void* ptr = pymalloc_alloc(ctx, nbytes); if (LIKELY(ptr != NULL)) { memset(ptr, 0, nbytes); return ptr; } ptr = PyMem_RawCalloc(nelem, elsize); if (ptr != NULL) { raw_allocated_blocks++; } return ptr; } static void insert_to_usedpool(poolp pool) { assert(pool->ref.count > 0); /* else the pool is empty */ uint size = pool->szidx; poolp next = usedpools[size + size]; poolp prev = next->prevpool; /* insert pool before next: prev <-> pool <-> next */ pool->nextpool = next; pool->prevpool = prev; next->prevpool = pool; prev->nextpool = pool; } static void insert_to_freepool(poolp pool) { poolp next = pool->nextpool; poolp prev = pool->prevpool; next->prevpool = prev; prev->nextpool = next; /* Link the pool to freepools. This is a singly-linked * list, and pool->prevpool isn't used there. */ struct arena_object *ao = &arenas[pool->arenaindex]; pool->nextpool = ao->freepools; ao->freepools = pool; uint nf = ao->nfreepools; /* If this is the rightmost arena with this number of free pools, * nfp2lasta[nf] needs to change. Caution: if nf is 0, there * are no arenas in usable_arenas with that value. */ struct arena_object* lastnf = nfp2lasta[nf]; assert((nf == 0 && lastnf == NULL) || (nf > 0 && lastnf != NULL && lastnf->nfreepools == nf && (lastnf->nextarena == NULL || nf < lastnf->nextarena->nfreepools))); if (lastnf == ao) { /* it is the rightmost */ struct arena_object* p = ao->prevarena; nfp2lasta[nf] = (p != NULL && p->nfreepools == nf) ? p : NULL; } ao->nfreepools = ++nf; /* All the rest is arena management. We just freed * a pool, and there are 4 cases for arena mgmt: * 1. If all the pools are free, return the arena to * the system free(). Except if this is the last * arena in the list, keep it to avoid thrashing: * keeping one wholly free arena in the list avoids * pathological cases where a simple loop would * otherwise provoke needing to allocate and free an * arena on every iteration. See bpo-37257. * 2. If this is the only free pool in the arena, * add the arena back to the `usable_arenas` list. * 3. If the "next" arena has a smaller count of free * pools, we have to "slide this arena right" to * restore that usable_arenas is sorted in order of * nfreepools. * 4. Else there's nothing more to do. */ if (nf == ao->ntotalpools && ao->nextarena != NULL) { /* Case 1. First unlink ao from usable_arenas. */ assert(ao->prevarena == NULL || ao->prevarena->address != 0); assert(ao ->nextarena == NULL || ao->nextarena->address != 0); /* Fix the pointer in the prevarena, or the * usable_arenas pointer. */ if (ao->prevarena == NULL) { usable_arenas = ao->nextarena; assert(usable_arenas == NULL || usable_arenas->address != 0); } else { assert(ao->prevarena->nextarena == ao); ao->prevarena->nextarena = ao->nextarena; } /* Fix the pointer in the nextarena. */ if (ao->nextarena != NULL) { assert(ao->nextarena->prevarena == ao); ao->nextarena->prevarena = ao->prevarena; } /* Record that this arena_object slot is * available to be reused. */ ao->nextarena = unused_arena_objects; unused_arena_objects = ao; #if WITH_PYMALLOC_RADIX_TREE /* mark arena region as not under control of obmalloc */ arena_map_mark_used(ao->address, 0); #endif /* Free the entire arena. */ _PyObject_Arena.free(_PyObject_Arena.ctx, (void *)ao->address, ARENA_SIZE); ao->address = 0; /* mark unassociated */ --narenas_currently_allocated; return; } if (nf == 1) { /* Case 2. Put ao at the head of * usable_arenas. Note that because * ao->nfreepools was 0 before, ao isn't * currently on the usable_arenas list. */ ao->nextarena = usable_arenas; ao->prevarena = NULL; if (usable_arenas) usable_arenas->prevarena = ao; usable_arenas = ao; assert(usable_arenas->address != 0); if (nfp2lasta[1] == NULL) { nfp2lasta[1] = ao; } return; } /* If this arena is now out of order, we need to keep * the list sorted. The list is kept sorted so that * the "most full" arenas are used first, which allows * the nearly empty arenas to be completely freed. In * a few un-scientific tests, it seems like this * approach allowed a lot more memory to be freed. */ /* If this is the only arena with nf, record that. */ if (nfp2lasta[nf] == NULL) { nfp2lasta[nf] = ao; } /* else the rightmost with nf doesn't change */ /* If this was the rightmost of the old size, it remains in place. */ if (ao == lastnf) { /* Case 4. Nothing to do. */ return; } /* If ao were the only arena in the list, the last block would have * gotten us out. */ assert(ao->nextarena != NULL); /* Case 3: We have to move the arena towards the end of the list, * because it has more free pools than the arena to its right. It needs * to move to follow lastnf. * First unlink ao from usable_arenas. */ if (ao->prevarena != NULL) { /* ao isn't at the head of the list */ assert(ao->prevarena->nextarena == ao); ao->prevarena->nextarena = ao->nextarena; } else { /* ao is at the head of the list */ assert(usable_arenas == ao); usable_arenas = ao->nextarena; } ao->nextarena->prevarena = ao->prevarena; /* And insert after lastnf. */ ao->prevarena = lastnf; ao->nextarena = lastnf->nextarena; if (ao->nextarena != NULL) { ao->nextarena->prevarena = ao; } lastnf->nextarena = ao; /* Verify that the swaps worked. */ assert(ao->nextarena == NULL || nf <= ao->nextarena->nfreepools); assert(ao->prevarena == NULL || nf > ao->prevarena->nfreepools); assert(ao->nextarena == NULL || ao->nextarena->prevarena == ao); assert((usable_arenas == ao && ao->prevarena == NULL) || ao->prevarena->nextarena == ao); } /* Free a memory block allocated by pymalloc_alloc(). Return 1 if it was freed. Return 0 if the block was not allocated by pymalloc_alloc(). */ static inline int pymalloc_free(void *ctx, void *p) { assert(p != NULL); #ifdef WITH_VALGRIND if (UNLIKELY(running_on_valgrind > 0)) { return 0; } #endif poolp pool = POOL_ADDR(p); if (UNLIKELY(!address_in_range(p, pool))) { return 0; } /* We allocated this address. */ /* Link p to the start of the pool's freeblock list. Since * the pool had at least the p block outstanding, the pool * wasn't empty (so it's already in a usedpools[] list, or * was full and is in no list -- it's not in the freeblocks * list in any case). */ assert(pool->ref.count > 0); /* else it was empty */ block *lastfree = pool->freeblock; *(block **)p = lastfree; pool->freeblock = (block *)p; pool->ref.count--; if (UNLIKELY(lastfree == NULL)) { /* Pool was full, so doesn't currently live in any list: * link it to the front of the appropriate usedpools[] list. * This mimics LRU pool usage for new allocations and * targets optimal filling when several pools contain * blocks of the same size class. */ insert_to_usedpool(pool); return 1; } /* freeblock wasn't NULL, so the pool wasn't full, * and the pool is in a usedpools[] list. */ if (LIKELY(pool->ref.count != 0)) { /* pool isn't empty: leave it in usedpools */ return 1; } /* Pool is now empty: unlink from usedpools, and * link to the front of freepools. This ensures that * previously freed pools will be allocated later * (being not referenced, they are perhaps paged out). */ insert_to_freepool(pool); return 1; } static void _PyObject_Free(void *ctx, void *p) { /* PyObject_Free(NULL) has no effect */ if (p == NULL) { return; } if (UNLIKELY(!pymalloc_free(ctx, p))) { /* pymalloc didn't allocate this address */ PyMem_RawFree(p); raw_allocated_blocks--; } } /* pymalloc realloc. If nbytes==0, then as the Python docs promise, we do not treat this like free(p), and return a non-NULL result. Return 1 if pymalloc reallocated memory and wrote the new pointer into newptr_p. Return 0 if pymalloc didn't allocated p. */ static int pymalloc_realloc(void *ctx, void **newptr_p, void *p, size_t nbytes) { void *bp; poolp pool; size_t size; assert(p != NULL); #ifdef WITH_VALGRIND /* Treat running_on_valgrind == -1 the same as 0 */ if (UNLIKELY(running_on_valgrind > 0)) { return 0; } #endif pool = POOL_ADDR(p); if (!address_in_range(p, pool)) { /* pymalloc is not managing this block. If nbytes <= SMALL_REQUEST_THRESHOLD, it's tempting to try to take over this block. However, if we do, we need to copy the valid data from the C-managed block to one of our blocks, and there's no portable way to know how much of the memory space starting at p is valid. As bug 1185883 pointed out the hard way, it's possible that the C-managed block is "at the end" of allocated VM space, so that a memory fault can occur if we try to copy nbytes bytes starting at p. Instead we punt: let C continue to manage this block. */ return 0; } /* pymalloc is in charge of this block */ size = INDEX2SIZE(pool->szidx); if (nbytes <= size) { /* The block is staying the same or shrinking. If it's shrinking, there's a tradeoff: it costs cycles to copy the block to a smaller size class, but it wastes memory not to copy it. The compromise here is to copy on shrink only if at least 25% of size can be shaved off. */ if (4 * nbytes > 3 * size) { /* It's the same, or shrinking and new/old > 3/4. */ *newptr_p = p; return 1; } size = nbytes; } bp = _PyObject_Malloc(ctx, nbytes); if (bp != NULL) { memcpy(bp, p, size); _PyObject_Free(ctx, p); } *newptr_p = bp; return 1; } static void * _PyObject_Realloc(void *ctx, void *ptr, size_t nbytes) { void *ptr2; if (ptr == NULL) { return _PyObject_Malloc(ctx, nbytes); } if (pymalloc_realloc(ctx, &ptr2, ptr, nbytes)) { return ptr2; } return PyMem_RawRealloc(ptr, nbytes); } #else /* ! WITH_PYMALLOC */ /*==========================================================================*/ /* pymalloc not enabled: Redirect the entry points to malloc. These will * only be used by extensions that are compiled with pymalloc enabled. */ Py_ssize_t _Py_GetAllocatedBlocks(void) { return 0; } #endif /* WITH_PYMALLOC */ /*==========================================================================*/ /* A x-platform debugging allocator. This doesn't manage memory directly, * it wraps a real allocator, adding extra debugging info to the memory blocks. */ /* Uncomment this define to add the "serialno" field */ /* #define PYMEM_DEBUG_SERIALNO */ #ifdef PYMEM_DEBUG_SERIALNO static size_t serialno = 0; /* incremented on each debug {m,re}alloc */ /* serialno is always incremented via calling this routine. The point is * to supply a single place to set a breakpoint. */ static void bumpserialno(void) { ++serialno; } #endif #define SST SIZEOF_SIZE_T #ifdef PYMEM_DEBUG_SERIALNO # define PYMEM_DEBUG_EXTRA_BYTES 4 * SST #else # define PYMEM_DEBUG_EXTRA_BYTES 3 * SST #endif /* Read sizeof(size_t) bytes at p as a big-endian size_t. */ static size_t read_size_t(const void *p) { const uint8_t *q = (const uint8_t *)p; size_t result = *q++; int i; for (i = SST; --i > 0; ++q) result = (result << 8) | *q; return result; } /* Write n as a big-endian size_t, MSB at address p, LSB at * p + sizeof(size_t) - 1. */ static void write_size_t(void *p, size_t n) { uint8_t *q = (uint8_t *)p + SST - 1; int i; for (i = SST; --i >= 0; --q) { *q = (uint8_t)(n & 0xff); n >>= 8; } } /* Let S = sizeof(size_t). The debug malloc asks for 4 * S extra bytes and fills them with useful stuff, here calling the underlying malloc's result p: p[0: S] Number of bytes originally asked for. This is a size_t, big-endian (easier to read in a memory dump). p[S] API ID. See PEP 445. This is a character, but seems undocumented. p[S+1: 2*S] Copies of PYMEM_FORBIDDENBYTE. Used to catch under- writes and reads. p[2*S: 2*S+n] The requested memory, filled with copies of PYMEM_CLEANBYTE. Used to catch reference to uninitialized memory. &p[2*S] is returned. Note that this is 8-byte aligned if pymalloc handled the request itself. p[2*S+n: 2*S+n+S] Copies of PYMEM_FORBIDDENBYTE. Used to catch over- writes and reads. p[2*S+n+S: 2*S+n+2*S] A serial number, incremented by 1 on each call to _PyMem_DebugMalloc and _PyMem_DebugRealloc. This is a big-endian size_t. If "bad memory" is detected later, the serial number gives an excellent way to set a breakpoint on the next run, to capture the instant at which this block was passed out. If PYMEM_DEBUG_SERIALNO is not defined (default), the debug malloc only asks for 3 * S extra bytes, and omits the last serialno field. */ static void * _PyMem_DebugRawAlloc(int use_calloc, void *ctx, size_t nbytes) { debug_alloc_api_t *api = (debug_alloc_api_t *)ctx; uint8_t *p; /* base address of malloc'ed pad block */ uint8_t *data; /* p + 2*SST == pointer to data bytes */ uint8_t *tail; /* data + nbytes == pointer to tail pad bytes */ size_t total; /* nbytes + PYMEM_DEBUG_EXTRA_BYTES */ if (nbytes > (size_t)PY_SSIZE_T_MAX - PYMEM_DEBUG_EXTRA_BYTES) { /* integer overflow: can't represent total as a Py_ssize_t */ return NULL; } total = nbytes + PYMEM_DEBUG_EXTRA_BYTES; /* Layout: [SSSS IFFF CCCC...CCCC FFFF NNNN] ^--- p ^--- data ^--- tail S: nbytes stored as size_t I: API identifier (1 byte) F: Forbidden bytes (size_t - 1 bytes before, size_t bytes after) C: Clean bytes used later to store actual data N: Serial number stored as size_t If PYMEM_DEBUG_SERIALNO is not defined (default), the last NNNN field is omitted. */ if (use_calloc) { p = (uint8_t *)api->alloc.calloc(api->alloc.ctx, 1, total); } else { p = (uint8_t *)api->alloc.malloc(api->alloc.ctx, total); } if (p == NULL) { return NULL; } data = p + 2*SST; #ifdef PYMEM_DEBUG_SERIALNO bumpserialno(); #endif /* at p, write size (SST bytes), id (1 byte), pad (SST-1 bytes) */ write_size_t(p, nbytes); p[SST] = (uint8_t)api->api_id; memset(p + SST + 1, PYMEM_FORBIDDENBYTE, SST-1); if (nbytes > 0 && !use_calloc) { memset(data, PYMEM_CLEANBYTE, nbytes); } /* at tail, write pad (SST bytes) and serialno (SST bytes) */ tail = data + nbytes; memset(tail, PYMEM_FORBIDDENBYTE, SST); #ifdef PYMEM_DEBUG_SERIALNO write_size_t(tail + SST, serialno); #endif return data; } static void * _PyMem_DebugRawMalloc(void *ctx, size_t nbytes) { return _PyMem_DebugRawAlloc(0, ctx, nbytes); } static void * _PyMem_DebugRawCalloc(void *ctx, size_t nelem, size_t elsize) { size_t nbytes; assert(elsize == 0 || nelem <= (size_t)PY_SSIZE_T_MAX / elsize); nbytes = nelem * elsize; return _PyMem_DebugRawAlloc(1, ctx, nbytes); } /* The debug free first checks the 2*SST bytes on each end for sanity (in particular, that the FORBIDDENBYTEs with the api ID are still intact). Then fills the original bytes with PYMEM_DEADBYTE. Then calls the underlying free. */ static void _PyMem_DebugRawFree(void *ctx, void *p) { /* PyMem_Free(NULL) has no effect */ if (p == NULL) { return; } debug_alloc_api_t *api = (debug_alloc_api_t *)ctx; uint8_t *q = (uint8_t *)p - 2*SST; /* address returned from malloc */ size_t nbytes; _PyMem_DebugCheckAddress(__func__, api->api_id, p); nbytes = read_size_t(q); nbytes += PYMEM_DEBUG_EXTRA_BYTES; memset(q, PYMEM_DEADBYTE, nbytes); api->alloc.free(api->alloc.ctx, q); } static void * _PyMem_DebugRawRealloc(void *ctx, void *p, size_t nbytes) { if (p == NULL) { return _PyMem_DebugRawAlloc(0, ctx, nbytes); } debug_alloc_api_t *api = (debug_alloc_api_t *)ctx; uint8_t *head; /* base address of malloc'ed pad block */ uint8_t *data; /* pointer to data bytes */ uint8_t *r; uint8_t *tail; /* data + nbytes == pointer to tail pad bytes */ size_t total; /* 2 * SST + nbytes + 2 * SST */ size_t original_nbytes; #define ERASED_SIZE 64 uint8_t save[2*ERASED_SIZE]; /* A copy of erased bytes. */ _PyMem_DebugCheckAddress(__func__, api->api_id, p); data = (uint8_t *)p; head = data - 2*SST; original_nbytes = read_size_t(head); if (nbytes > (size_t)PY_SSIZE_T_MAX - PYMEM_DEBUG_EXTRA_BYTES) { /* integer overflow: can't represent total as a Py_ssize_t */ return NULL; } total = nbytes + PYMEM_DEBUG_EXTRA_BYTES; tail = data + original_nbytes; #ifdef PYMEM_DEBUG_SERIALNO size_t block_serialno = read_size_t(tail + SST); #endif /* Mark the header, the trailer, ERASED_SIZE bytes at the begin and ERASED_SIZE bytes at the end as dead and save the copy of erased bytes. */ if (original_nbytes <= sizeof(save)) { memcpy(save, data, original_nbytes); memset(data - 2 * SST, PYMEM_DEADBYTE, original_nbytes + PYMEM_DEBUG_EXTRA_BYTES); } else { memcpy(save, data, ERASED_SIZE); memset(head, PYMEM_DEADBYTE, ERASED_SIZE + 2 * SST); memcpy(&save[ERASED_SIZE], tail - ERASED_SIZE, ERASED_SIZE); memset(tail - ERASED_SIZE, PYMEM_DEADBYTE, ERASED_SIZE + PYMEM_DEBUG_EXTRA_BYTES - 2 * SST); } /* Resize and add decorations. */ r = (uint8_t *)api->alloc.realloc(api->alloc.ctx, head, total); if (r == NULL) { /* if realloc() failed: rewrite header and footer which have just been erased */ nbytes = original_nbytes; } else { head = r; #ifdef PYMEM_DEBUG_SERIALNO bumpserialno(); block_serialno = serialno; #endif } data = head + 2*SST; write_size_t(head, nbytes); head[SST] = (uint8_t)api->api_id; memset(head + SST + 1, PYMEM_FORBIDDENBYTE, SST-1); tail = data + nbytes; memset(tail, PYMEM_FORBIDDENBYTE, SST); #ifdef PYMEM_DEBUG_SERIALNO write_size_t(tail + SST, block_serialno); #endif /* Restore saved bytes. */ if (original_nbytes <= sizeof(save)) { memcpy(data, save, Py_MIN(nbytes, original_nbytes)); } else { size_t i = original_nbytes - ERASED_SIZE; memcpy(data, save, Py_MIN(nbytes, ERASED_SIZE)); if (nbytes > i) { memcpy(data + i, &save[ERASED_SIZE], Py_MIN(nbytes - i, ERASED_SIZE)); } } if (r == NULL) { return NULL; } if (nbytes > original_nbytes) { /* growing: mark new extra memory clean */ memset(data + original_nbytes, PYMEM_CLEANBYTE, nbytes - original_nbytes); } return data; } static inline void _PyMem_DebugCheckGIL(const char *func) { if (!PyGILState_Check()) { _Py_FatalErrorFunc(func, "Python memory allocator called " "without holding the GIL"); } } static void * _PyMem_DebugMalloc(void *ctx, size_t nbytes) { _PyMem_DebugCheckGIL(__func__); return _PyMem_DebugRawMalloc(ctx, nbytes); } static void * _PyMem_DebugCalloc(void *ctx, size_t nelem, size_t elsize) { _PyMem_DebugCheckGIL(__func__); return _PyMem_DebugRawCalloc(ctx, nelem, elsize); } static void _PyMem_DebugFree(void *ctx, void *ptr) { _PyMem_DebugCheckGIL(__func__); _PyMem_DebugRawFree(ctx, ptr); } static void * _PyMem_DebugRealloc(void *ctx, void *ptr, size_t nbytes) { _PyMem_DebugCheckGIL(__func__); return _PyMem_DebugRawRealloc(ctx, ptr, nbytes); } /* Check the forbidden bytes on both ends of the memory allocated for p. * If anything is wrong, print info to stderr via _PyObject_DebugDumpAddress, * and call Py_FatalError to kill the program. * The API id, is also checked. */ static void _PyMem_DebugCheckAddress(const char *func, char api, const void *p) { assert(p != NULL); const uint8_t *q = (const uint8_t *)p; size_t nbytes; const uint8_t *tail; int i; char id; /* Check the API id */ id = (char)q[-SST]; if (id != api) { _PyObject_DebugDumpAddress(p); _Py_FatalErrorFormat(func, "bad ID: Allocated using API '%c', " "verified using API '%c'", id, api); } /* Check the stuff at the start of p first: if there's underwrite * corruption, the number-of-bytes field may be nuts, and checking * the tail could lead to a segfault then. */ for (i = SST-1; i >= 1; --i) { if (*(q-i) != PYMEM_FORBIDDENBYTE) { _PyObject_DebugDumpAddress(p); _Py_FatalErrorFunc(func, "bad leading pad byte"); } } nbytes = read_size_t(q - 2*SST); tail = q + nbytes; for (i = 0; i < SST; ++i) { if (tail[i] != PYMEM_FORBIDDENBYTE) { _PyObject_DebugDumpAddress(p); _Py_FatalErrorFunc(func, "bad trailing pad byte"); } } } /* Display info to stderr about the memory block at p. */ static void _PyObject_DebugDumpAddress(const void *p) { const uint8_t *q = (const uint8_t *)p; const uint8_t *tail; size_t nbytes; int i; int ok; char id; fprintf(stderr, "Debug memory block at address p=%p:", p); if (p == NULL) { fprintf(stderr, "\n"); return; } id = (char)q[-SST]; fprintf(stderr, " API '%c'\n", id); nbytes = read_size_t(q - 2*SST); fprintf(stderr, " %zu bytes originally requested\n", nbytes); /* In case this is nuts, check the leading pad bytes first. */ fprintf(stderr, " The %d pad bytes at p-%d are ", SST-1, SST-1); ok = 1; for (i = 1; i <= SST-1; ++i) { if (*(q-i) != PYMEM_FORBIDDENBYTE) { ok = 0; break; } } if (ok) fputs("FORBIDDENBYTE, as expected.\n", stderr); else { fprintf(stderr, "not all FORBIDDENBYTE (0x%02x):\n", PYMEM_FORBIDDENBYTE); for (i = SST-1; i >= 1; --i) { const uint8_t byte = *(q-i); fprintf(stderr, " at p-%d: 0x%02x", i, byte); if (byte != PYMEM_FORBIDDENBYTE) fputs(" *** OUCH", stderr); fputc('\n', stderr); } fputs(" Because memory is corrupted at the start, the " "count of bytes requested\n" " may be bogus, and checking the trailing pad " "bytes may segfault.\n", stderr); } tail = q + nbytes; fprintf(stderr, " The %d pad bytes at tail=%p are ", SST, (void *)tail); ok = 1; for (i = 0; i < SST; ++i) { if (tail[i] != PYMEM_FORBIDDENBYTE) { ok = 0; break; } } if (ok) fputs("FORBIDDENBYTE, as expected.\n", stderr); else { fprintf(stderr, "not all FORBIDDENBYTE (0x%02x):\n", PYMEM_FORBIDDENBYTE); for (i = 0; i < SST; ++i) { const uint8_t byte = tail[i]; fprintf(stderr, " at tail+%d: 0x%02x", i, byte); if (byte != PYMEM_FORBIDDENBYTE) fputs(" *** OUCH", stderr); fputc('\n', stderr); } } #ifdef PYMEM_DEBUG_SERIALNO size_t serial = read_size_t(tail + SST); fprintf(stderr, " The block was made by call #%zu to debug malloc/realloc.\n", serial); #endif if (nbytes > 0) { i = 0; fputs(" Data at p:", stderr); /* print up to 8 bytes at the start */ while (q < tail && i < 8) { fprintf(stderr, " %02x", *q); ++i; ++q; } /* and up to 8 at the end */ if (q < tail) { if (tail - q > 8) { fputs(" ...", stderr); q = tail - 8; } while (q < tail) { fprintf(stderr, " %02x", *q); ++q; } } fputc('\n', stderr); } fputc('\n', stderr); fflush(stderr); _PyMem_DumpTraceback(fileno(stderr), p); } static size_t printone(FILE *out, const char* msg, size_t value) { int i, k; char buf[100]; size_t origvalue = value; fputs(msg, out); for (i = (int)strlen(msg); i < 35; ++i) fputc(' ', out); fputc('=', out); /* Write the value with commas. */ i = 22; buf[i--] = '\0'; buf[i--] = '\n'; k = 3; do { size_t nextvalue = value / 10; unsigned int digit = (unsigned int)(value - nextvalue * 10); value = nextvalue; buf[i--] = (char)(digit + '0'); --k; if (k == 0 && value && i >= 0) { k = 3; buf[i--] = ','; } } while (value && i >= 0); while (i >= 0) buf[i--] = ' '; fputs(buf, out); return origvalue; } void _PyDebugAllocatorStats(FILE *out, const char *block_name, int num_blocks, size_t sizeof_block) { char buf1[128]; char buf2[128]; PyOS_snprintf(buf1, sizeof(buf1), "%d %ss * %zd bytes each", num_blocks, block_name, sizeof_block); PyOS_snprintf(buf2, sizeof(buf2), "%48s ", buf1); (void)printone(out, buf2, num_blocks * sizeof_block); } #ifdef WITH_PYMALLOC #ifdef Py_DEBUG /* Is target in the list? The list is traversed via the nextpool pointers. * The list may be NULL-terminated, or circular. Return 1 if target is in * list, else 0. */ static int pool_is_in_list(const poolp target, poolp list) { poolp origlist = list; assert(target != NULL); if (list == NULL) return 0; do { if (target == list) return 1; list = list->nextpool; } while (list != NULL && list != origlist); return 0; } #endif /* Print summary info to "out" about the state of pymalloc's structures. * In Py_DEBUG mode, also perform some expensive internal consistency * checks. * * Return 0 if the memory debug hooks are not installed or no statistics was * written into out, return 1 otherwise. */ int _PyObject_DebugMallocStats(FILE *out) { if (!_PyMem_PymallocEnabled()) { return 0; } uint i; const uint numclasses = SMALL_REQUEST_THRESHOLD >> ALIGNMENT_SHIFT; /* # of pools, allocated blocks, and free blocks per class index */ size_t numpools[SMALL_REQUEST_THRESHOLD >> ALIGNMENT_SHIFT]; size_t numblocks[SMALL_REQUEST_THRESHOLD >> ALIGNMENT_SHIFT]; size_t numfreeblocks[SMALL_REQUEST_THRESHOLD >> ALIGNMENT_SHIFT]; /* total # of allocated bytes in used and full pools */ size_t allocated_bytes = 0; /* total # of available bytes in used pools */ size_t available_bytes = 0; /* # of free pools + pools not yet carved out of current arena */ uint numfreepools = 0; /* # of bytes for arena alignment padding */ size_t arena_alignment = 0; /* # of bytes in used and full pools used for pool_headers */ size_t pool_header_bytes = 0; /* # of bytes in used and full pools wasted due to quantization, * i.e. the necessarily leftover space at the ends of used and * full pools. */ size_t quantization = 0; /* # of arenas actually allocated. */ size_t narenas = 0; /* running total -- should equal narenas * ARENA_SIZE */ size_t total; char buf[128]; fprintf(out, "Small block threshold = %d, in %u size classes.\n", SMALL_REQUEST_THRESHOLD, numclasses); for (i = 0; i < numclasses; ++i) numpools[i] = numblocks[i] = numfreeblocks[i] = 0; /* Because full pools aren't linked to from anything, it's easiest * to march over all the arenas. If we're lucky, most of the memory * will be living in full pools -- would be a shame to miss them. */ for (i = 0; i < maxarenas; ++i) { uint j; uintptr_t base = arenas[i].address; /* Skip arenas which are not allocated. */ if (arenas[i].address == (uintptr_t)NULL) continue; narenas += 1; numfreepools += arenas[i].nfreepools; /* round up to pool alignment */ if (base & (uintptr_t)POOL_SIZE_MASK) { arena_alignment += POOL_SIZE; base &= ~(uintptr_t)POOL_SIZE_MASK; base += POOL_SIZE; } /* visit every pool in the arena */ assert(base <= (uintptr_t) arenas[i].pool_address); for (j = 0; base < (uintptr_t) arenas[i].pool_address; ++j, base += POOL_SIZE) { poolp p = (poolp)base; const uint sz = p->szidx; uint freeblocks; if (p->ref.count == 0) { /* currently unused */ #ifdef Py_DEBUG assert(pool_is_in_list(p, arenas[i].freepools)); #endif continue; } ++numpools[sz]; numblocks[sz] += p->ref.count; freeblocks = NUMBLOCKS(sz) - p->ref.count; numfreeblocks[sz] += freeblocks; #ifdef Py_DEBUG if (freeblocks > 0) assert(pool_is_in_list(p, usedpools[sz + sz])); #endif } } assert(narenas == narenas_currently_allocated); fputc('\n', out); fputs("class size num pools blocks in use avail blocks\n" "----- ---- --------- ------------- ------------\n", out); for (i = 0; i < numclasses; ++i) { size_t p = numpools[i]; size_t b = numblocks[i]; size_t f = numfreeblocks[i]; uint size = INDEX2SIZE(i); if (p == 0) { assert(b == 0 && f == 0); continue; } fprintf(out, "%5u %6u %11zu %15zu %13zu\n", i, size, p, b, f); allocated_bytes += b * size; available_bytes += f * size; pool_header_bytes += p * POOL_OVERHEAD; quantization += p * ((POOL_SIZE - POOL_OVERHEAD) % size); } fputc('\n', out); #ifdef PYMEM_DEBUG_SERIALNO if (_PyMem_DebugEnabled()) { (void)printone(out, "# times object malloc called", serialno); } #endif (void)printone(out, "# arenas allocated total", ntimes_arena_allocated); (void)printone(out, "# arenas reclaimed", ntimes_arena_allocated - narenas); (void)printone(out, "# arenas highwater mark", narenas_highwater); (void)printone(out, "# arenas allocated current", narenas); PyOS_snprintf(buf, sizeof(buf), "%zu arenas * %d bytes/arena", narenas, ARENA_SIZE); (void)printone(out, buf, narenas * ARENA_SIZE); fputc('\n', out); /* Account for what all of those arena bytes are being used for. */ total = printone(out, "# bytes in allocated blocks", allocated_bytes); total += printone(out, "# bytes in available blocks", available_bytes); PyOS_snprintf(buf, sizeof(buf), "%u unused pools * %d bytes", numfreepools, POOL_SIZE); total += printone(out, buf, (size_t)numfreepools * POOL_SIZE); total += printone(out, "# bytes lost to pool headers", pool_header_bytes); total += printone(out, "# bytes lost to quantization", quantization); total += printone(out, "# bytes lost to arena alignment", arena_alignment); (void)printone(out, "Total", total); assert(narenas * ARENA_SIZE == total); #if WITH_PYMALLOC_RADIX_TREE fputs("\narena map counts\n", out); #ifdef USE_INTERIOR_NODES (void)printone(out, "# arena map mid nodes", arena_map_mid_count); (void)printone(out, "# arena map bot nodes", arena_map_bot_count); fputc('\n', out); #endif total = printone(out, "# bytes lost to arena map root", sizeof(arena_map_root)); #ifdef USE_INTERIOR_NODES total += printone(out, "# bytes lost to arena map mid", sizeof(arena_map_mid_t) * arena_map_mid_count); total += printone(out, "# bytes lost to arena map bot", sizeof(arena_map_bot_t) * arena_map_bot_count); (void)printone(out, "Total", total); #endif #endif return 1; } #endif /* #ifdef WITH_PYMALLOC */