The quilt patch titled
Subject: mm: multi-gen LRU: walk_pte_range() use pte_offset_map_rw_nolock()
has been removed from the -mm tree. Its filename was
mm-multi-gen-lru-walk_pte_range-use-pte_offset_map_rw_nolock.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Subject: mm: multi-gen LRU: walk_pte_range() use pte_offset_map_rw_nolock()
Date: Thu, 26 Sep 2024 14:46:25 +0800
In walk_pte_range(), we may modify the pte entry after holding the ptl, so
convert it to using pte_offset_map_rw_nolock(). At this time, the
pte_same() check is not performed after the ptl held, so we should get
pmdval and do pmd_same() check to ensure the stability of pmd entry.
Link: https://lkml.kernel.org/r/7e9c194a5efacc9609cfd31abb9c7df88b53b530.1727332572.git.zhengqi.arch@xxxxxxxxxxxxx
Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Reviewed-by: Muchun Song <muchun.song@xxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Vishal Moola (Oracle) <vishal.moola@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
--- a/mm/vmscan.c~mm-multi-gen-lru-walk_pte_range-use-pte_offset_map_rw_nolock
+++ a/mm/vmscan.c
@@ -3386,8 +3386,10 @@ static bool walk_pte_range(pmd_t *pmd, u
struct pglist_data *pgdat = lruvec_pgdat(walk->lruvec);
DEFINE_MAX_SEQ(walk->lruvec);
int old_gen, new_gen = lru_gen_from_seq(max_seq);
+ pmd_t pmdval;
- pte = pte_offset_map_nolock(args->mm, pmd, start & PMD_MASK, &ptl);
+ pte = pte_offset_map_rw_nolock(args->mm, pmd, start & PMD_MASK, &pmdval,
+ &ptl);
if (!pte)
return false;
if (!spin_trylock(ptl)) {
@@ -3395,6 +3397,11 @@ static bool walk_pte_range(pmd_t *pmd, u
return false;
}
+ if (unlikely(!pmd_same(pmdval, pmdp_get_lockless(pmd)))) {
+ pte_unmap_unlock(pte, ptl);
+ return false;
+ }
+
arch_enter_lazy_mmu_mode();
restart:
for (i = pte_index(start), addr = start; addr != end; i++, addr += PAGE_SIZE) {
_
Patches currently in -mm which might be from zhengqi.arch@xxxxxxxxxxxxx are
