The quilt patch titled
Subject: mm/smaps: don't access young/dirty bit if pte unpresent
has been removed from the -mm tree. Its filename was
mm-smaps-dont-access-young-dirty-bit-if-pte-unpresent.patch
This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Peter Xu <peterx@xxxxxxxxxx>
Subject: mm/smaps: don't access young/dirty bit if pte unpresent
Date: Fri, 5 Aug 2022 12:00:03 -0400
These bits should only be valid when the ptes are present. Introducing
two booleans for it and set it to false when !pte_present() for both pte
and pmd accountings.
The bug is found during code reading and no real world issue reported, but
logically such an error can cause incorrect readings for either smaps or
smaps_rollup output on quite a few fields.
For example, it could cause over-estimate on values like Shared_Dirty,
Private_Dirty, Referenced. Or it could also cause under-estimate on
values like LazyFree, Shared_Clean, Private_Clean.
Link: https://lkml.kernel.org/r/20220805160003.58929-1-peterx@xxxxxxxxxx
Fixes: b1d4d9e0cbd0 ("proc/smaps: carefully handle migration entries")
Fixes: c94b6923fa0a ("/proc/PID/smaps: Add PMD migration entry parsing")
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Yang Shi <shy828301@xxxxxxxxx>
Cc: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
--- a/fs/proc/task_mmu.c~mm-smaps-dont-access-young-dirty-bit-if-pte-unpresent
+++ a/fs/proc/task_mmu.c
@@ -527,10 +527,12 @@ static void smaps_pte_entry(pte_t *pte,
struct vm_area_struct *vma = walk->vma;
bool locked = !!(vma->vm_flags & VM_LOCKED);
struct page *page = NULL;
- bool migration = false;
+ bool migration = false, young = false, dirty = false;
if (pte_present(*pte)) {
page = vm_normal_page(vma, addr, *pte);
+ young = pte_young(*pte);
+ dirty = pte_dirty(*pte);
} else if (is_swap_pte(*pte)) {
swp_entry_t swpent = pte_to_swp_entry(*pte);
@@ -560,8 +562,7 @@ static void smaps_pte_entry(pte_t *pte,
if (!page)
return;
- smaps_account(mss, page, false, pte_young(*pte), pte_dirty(*pte),
- locked, migration);
+ smaps_account(mss, page, false, young, dirty, locked, migration);
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
_
Patches currently in -mm which might be from peterx@xxxxxxxxxx are
mm-x86-use-swp_type_bits-in-3-level-swap-macros.patch
mm-swap-comment-all-the-ifdef-in-swapopsh.patch
mm-swap-add-swp_offset_pfn-to-fetch-pfn-from-swap-entry.patch
mm-thp-carry-over-dirty-bit-when-thp-splits-on-pmd.patch
mm-remember-young-dirty-bit-for-page-migrations.patch
mm-swap-cache-maximum-swapfile-size-when-init-swap.patch
mm-swap-cache-swap-migration-a-d-bits-support.patch
