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Put guard pages next to fast alloc memory (#6885)

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* Put guard pages next to fast alloc memory

I verified that we can now detect #6753 without creating tons of
threads.

* Use pageSize instead of 4096

* Don't include mmapInternal for windows
This commit is contained in:
Andrew Noyes 2022-04-19 11:22:35 -07:00 committed by GitHub
parent eedac50bb5
commit 297d831192
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 23 additions and 8 deletions
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2
flow/FastAlloc.cpp
View File

@ -519,7 +519,7 @@ void FastAllocator<Size>::getMagazine() {
--g_allocation_tracing_disabled;
}
#endif
block = (void**)::allocate(magazine_size * Size, false);
block = (void**)::allocate(magazine_size * Size, /*allowLargePages*/ false, /*includeGuardPages*/ true);
#endif
// void** block = new void*[ magazine_size * PSize ];

27
flow/Platform.actor.cpp
View File

@ -2037,7 +2037,22 @@ static void enableLargePages() {
#endif
}
static void* allocateInternal(size_t length, bool largePages) {
#ifndef _WIN32
static void* mmapInternal(size_t length, int flags, bool guardPages) {
if (guardPages) {
constexpr size_t pageSize = 4096;
length += 2 * pageSize; // Map enough for the guard pages
void* resultWithGuardPages = mmap(nullptr, length, PROT_READ | PROT_WRITE, flags, -1, 0);
mprotect(resultWithGuardPages, pageSize, PROT_NONE); // left guard page
mprotect((void*)(uintptr_t(resultWithGuardPages) + length - pageSize), pageSize, PROT_NONE); // right guard page
return (void*)(uintptr_t(resultWithGuardPages) + pageSize);
} else {
return mmap(nullptr, length, PROT_READ | PROT_WRITE, flags, -1, 0);
}
}
#endif
static void* allocateInternal(size_t length, bool largePages, bool guardPages) {
#ifdef _WIN32
DWORD allocType = MEM_COMMIT | MEM_RESERVE;
@ -2052,31 +2067,31 @@ static void* allocateInternal(size_t length, bool largePages) {
if (largePages)
flags |= MAP_HUGETLB;
return mmap(nullptr, length, PROT_READ | PROT_WRITE, flags, -1, 0);
return mmapInternal(length, flags, guardPages);
#elif defined(__APPLE__) || defined(__FreeBSD__)
int flags = MAP_PRIVATE | MAP_ANON;
return mmap(nullptr, length, PROT_READ | PROT_WRITE, flags, -1, 0);
return mmapInternal(length, flags, guardPages);
#else
#error Port me!
#endif
}
static bool largeBlockFail = false;
void* allocate(size_t length, bool allowLargePages) {
void* allocate(size_t length, bool allowLargePages, bool includeGuardPages) {
if (allowLargePages)
enableLargePages();
void* block = ALLOC_FAIL;
if (allowLargePages && !largeBlockFail) {
block = allocateInternal(length, true);
block = allocateInternal(length, true, includeGuardPages);
if (block == ALLOC_FAIL)
largeBlockFail = true;
}
if (block == ALLOC_FAIL)
block = allocateInternal(length, false);
block = allocateInternal(length, false, includeGuardPages);
// FIXME: SevWarnAlways trace if "close" to out of memory

2
flow/Platform.h
View File

@ -284,7 +284,7 @@ std::string epochsToGMTString(double epochs);
void setMemoryQuota(size_t limit);
void* allocate(size_t length, bool allowLargePages);
void* allocate(size_t length, bool allowLargePages, bool includeGuardPages);
void setAffinity(int proc);