Remove the KSM hack in mmap().
We've been telling people not to use KSM since 2018.
Bug: http://b/115637122
Test: treehugger
Change-Id: Iaa4e0e31e449a74700b6ed47881b9625556f0982
diff --git a/libc/bionic/mmap.cpp b/libc/bionic/mmap.cpp
index 9aad0b3..ed6b9c6 100644
--- a/libc/bionic/mmap.cpp
+++ b/libc/bionic/mmap.cpp
@@ -39,37 +39,20 @@
#define MMAP2_SHIFT 12 // 2**12 == 4096
-static bool kernel_has_MADV_MERGEABLE = true;
-
void* mmap64(void* addr, size_t size, int prot, int flags, int fd, off64_t offset) {
if (offset < 0 || (offset & ((1UL << MMAP2_SHIFT)-1)) != 0) {
errno = EINVAL;
return MAP_FAILED;
}
- // prevent allocations large enough for `end - start` to overflow
+ // Prevent allocations large enough for `end - start` to overflow.
size_t rounded = __BIONIC_ALIGN(size, PAGE_SIZE);
if (rounded < size || rounded > PTRDIFF_MAX) {
errno = ENOMEM;
return MAP_FAILED;
}
- bool is_private_anonymous =
- (flags & (MAP_PRIVATE | MAP_ANONYMOUS)) == (MAP_PRIVATE | MAP_ANONYMOUS);
- bool is_stack_or_grows_down = (flags & (MAP_STACK | MAP_GROWSDOWN)) != 0;
-
- void* result = __mmap2(addr, size, prot, flags, fd, offset >> MMAP2_SHIFT);
-
- if (result != MAP_FAILED && kernel_has_MADV_MERGEABLE &&
- is_private_anonymous && !is_stack_or_grows_down) {
- ErrnoRestorer errno_restorer;
- int rc = madvise(result, size, MADV_MERGEABLE);
- if (rc == -1 && errno == EINVAL) {
- kernel_has_MADV_MERGEABLE = false;
- }
- }
-
- return result;
+ return __mmap2(addr, size, prot, flags, fd, offset >> MMAP2_SHIFT);
}
void* mmap(void* addr, size_t size, int prot, int flags, int fd, off_t offset) {