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use proper file descriptor in mmap for decommit

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daan 2020-09-05 22:16:58 -07:00
parent f7dc4847f2
commit f9ca7cd05a
1 changed files with 15 additions and 9 deletions
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24
src/os.c
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@ -345,6 +345,17 @@ static void* mi_unix_mmapx(void* addr, size_t size, size_t try_alignment, int pr
return p;
}
static int mi_unix_mmap_fd(void) {
#if defined(VM_MAKE_TAG)
// macOS: tracking anonymous page with a specific ID. (All up to 98 are taken officially but LLVM sanitizers had taken 99)
int os_tag = (int)mi_option_get(mi_option_os_tag);
if (os_tag < 100 || os_tag > 255) os_tag = 100;
return VM_MAKE_TAG(os_tag);
#else
return -1;
#endif
}
static void* mi_unix_mmap(void* addr, size_t size, size_t try_alignment, int protect_flags, bool large_only, bool allow_large, bool* is_large) {
void* p = NULL;
#if !defined(MAP_ANONYMOUS)
@ -354,7 +365,7 @@ static void* mi_unix_mmap(void* addr, size_t size, size_t try_alignment, int pro
#define MAP_NORESERVE 0
#endif
int flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE;
int fd = -1;
const int fd = mi_unix_mmap_fd();
#if defined(MAP_ALIGNED) // BSD
if (try_alignment > 0) {
size_t n = _mi_bsr(try_alignment);
@ -365,13 +376,7 @@ static void* mi_unix_mmap(void* addr, size_t size, size_t try_alignment, int pro
#endif
#if defined(PROT_MAX)
protect_flags |= PROT_MAX(PROT_READ | PROT_WRITE); // BSD
#endif
#if defined(VM_MAKE_TAG)
// macOS: tracking anonymous page with a specific ID. (All up to 98 are taken officially but LLVM sanitizers had taken 99)
int os_tag = (int)mi_option_get(mi_option_os_tag);
if (os_tag < 100 || os_tag > 255) os_tag = 100;
fd = VM_MAKE_TAG(os_tag);
#endif
#endif
if ((large_only || use_large_os_page(size, try_alignment)) && allow_large) {
static _Atomic(uintptr_t) large_page_try_ok; // = 0;
uintptr_t try_ok = mi_atomic_load_acquire(&large_page_try_ok);
@ -713,7 +718,8 @@ static bool mi_os_commitx(void* addr, size_t size, bool commit, bool conservativ
#elif defined(MAP_FIXED)
if (!commit) {
// use mmap with MAP_FIXED to discard the existing memory (and reduce commit charge)
void* p = mmap(start, csize, PROT_NONE, (MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE), -1, 0);
const int fd = mi_unix_mmap_fd();
void* p = mmap(start, csize, PROT_NONE, (MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE), fd, 0);
if (p != start) { err = errno; }
}
else {