The patch titled
Subject: mm/damon: validate if the pmd entry is present before accessing
has been added to the -mm mm-unstable branch. Its filename is
mm-damon-validate-if-the-pmd-entry-is-present-before-accessing.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-validate-if-the-pmd-entry-is-present-before-accessing.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Subject: mm/damon: validate if the pmd entry is present before accessing
Date: Wed, 17 Aug 2022 14:21:12 +0800
The pmd_huge() is used to validate if the pmd entry is mapped by a huge
page, also including the case of non-present (migration or hwpoisoned) pmd
entry on arm64 or x86 architectures. Thus we should validate if it is
present before making the pmd entry old or getting young state, otherwise
we can not get the correct corresponding page.
Link: https://lkml.kernel.org/r/2838b6737bc259cf575ff11fd1c4b7fdb340fa73.1660717122.git.baolin.wang@xxxxxxxxxxxxxxxxx
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: SeongJae Park <sj@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/damon/vaddr.c | 10 ++++++++++
1 file changed, 10 insertions(+)
--- a/mm/damon/vaddr.c~mm-damon-validate-if-the-pmd-entry-is-present-before-accessing
+++ a/mm/damon/vaddr.c
@@ -304,6 +304,11 @@ static int damon_mkold_pmd_entry(pmd_t *
if (pmd_huge(*pmd)) {
ptl = pmd_lock(walk->mm, pmd);
+ if (!pmd_present(*pmd)) {
+ spin_unlock(ptl);
+ return 0;
+ }
+
if (pmd_huge(*pmd)) {
damon_pmdp_mkold(pmd, walk->mm, addr);
spin_unlock(ptl);
@@ -431,6 +436,11 @@ static int damon_young_pmd_entry(pmd_t *
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
if (pmd_huge(*pmd)) {
ptl = pmd_lock(walk->mm, pmd);
+ if (!pmd_present(*pmd)) {
+ spin_unlock(ptl);
+ return 0;
+ }
+
if (!pmd_huge(*pmd)) {
spin_unlock(ptl);
goto regular_page;
_
Patches currently in -mm which might be from baolin.wang@xxxxxxxxxxxxxxxxx are
mm-migrate-do-not-retry-10-times-for-the-subpages-of-fail-to-migrate-thp.patch
mm-damon-validate-if-the-pmd-entry-is-present-before-accessing.patch
