The patch titled
Subject: filemap: replace pte_offset_map() with pte_offset_map_nolock()
has been added to the -mm mm-unstable branch. Its filename is
filemap-replace-pte_offset_map-with-pte_offset_map_nolock.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/filemap-replace-pte_offset_map-with-pte_offset_map_nolock.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: ZhangPeng <zhangpeng362@xxxxxxxxxx>
Subject: filemap: replace pte_offset_map() with pte_offset_map_nolock()
Date: Wed, 13 Mar 2024 09:29:13 +0800
The vmf->ptl in filemap_fault_recheck_pte_none() is still set from
handle_pte_fault(). But at the same time, we did a pte_unmap(vmf->pte).
After a pte_unmap(vmf->pte) unmap and rcu_read_unlock(), the page table
may be racily changed and vmf->ptl maybe fails to protect the actual page
table. Fix this by replacing pte_offset_map() with
pte_offset_map_nolock().
Link: https://lkml.kernel.org/r/20240313012913.2395414-1-zhangpeng362@xxxxxxxxxx
Fixes: 58f327f2ce80 ("filemap: avoid unnecessary major faults in filemap_fault()")
Signed-off-by: ZhangPeng <zhangpeng362@xxxxxxxxxx>
Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Cc: "Huang, Ying" <ying.huang@xxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Nanyong Sun <sunnanyong@xxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: Yin Fengwei <fengwei.yin@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/filemap.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/filemap.c~filemap-replace-pte_offset_map-with-pte_offset_map_nolock
+++ a/mm/filemap.c
@@ -3207,7 +3207,8 @@ static vm_fault_t filemap_fault_recheck_
if (!(vmf->flags & FAULT_FLAG_ORIG_PTE_VALID))
return 0;
- ptep = pte_offset_map(vmf->pmd, vmf->address);
+ ptep = pte_offset_map_nolock(vma->vm_mm, vmf->pmd, vmf->address,
+ &vmf->ptl);
if (unlikely(!ptep))
return VM_FAULT_NOPAGE;
_
Patches currently in -mm which might be from zhangpeng362@xxxxxxxxxx are
filemap-replace-pte_offset_map-with-pte_offset_map_nolock.patch
