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src: large page attributing an id on Linux
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Using the new PR_SET_VMA_ANON_NAME prctl attribute available since
the 5.17 release, when rolling out the process address map appears as
`
<start>-<end> r-xp 0000000 00:00 0 [anon:nodejs Large Page]
`

PR-URL: #42644
Reviewed-By: James M Snell <jasnell@gmail.com>
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devnexen authored and targos committed Apr 28, 2022
1 parent 6b7c35e commit 1a7af63
Showing 1 changed file with 21 additions and 0 deletions.
21 changes: 21 additions & 0 deletions src/large_pages/node_large_page.cc
Original file line number Diff line number Diff line change
Expand Up @@ -68,6 +68,11 @@
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif // ifndef _GNU_SOURCE
#include <sys/prctl.h>
#if !defined(PR_SET_VMA)
#define PR_SET_VMA 0x53564d41
#define PR_SET_VMA_ANON_NAME 0
#endif
#elif defined(__FreeBSD__)
#include "uv.h" // uv_exepath
#endif // defined(__linux__)
Expand Down Expand Up @@ -312,6 +317,21 @@ class MemoryMapPointer {
mem_ = nullptr;
size_ = 0;
}
static void SetName(void* mem, size_t size, const char* name) {
#if defined(__linux__)
// Available since the 5.17 kernel release and if the
// CONFIG_ANON_VMA_NAME option, we can set an identifier
// to an anonymous mapped region. However if the kernel
// option is not present or it s an older kernel, it is a no-op.
if (mem != MAP_FAILED && mem != nullptr)
prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME,
reinterpret_cast<uintptr_t>(mem),
size,
reinterpret_cast<uintptr_t>(name));
#else
(void)name;
#endif
}
FORCE_INLINE ~MemoryMapPointer() {
if (mem_ == nullptr) return;
if (mem_ == MAP_FAILED) return;
Expand Down Expand Up @@ -382,6 +402,7 @@ MoveTextRegionToLargePages(const text_region& r) {
#endif

if (mprotect(start, size, PROT_READ | PROT_EXEC) == -1) goto fail;
MemoryMapPointer::SetName(start, size, "nodejs Large Page");

// We need not `munmap(tmem, size)` on success.
tmem.Reset();
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