Messages in this thread Patch in this message | | | From | Peng Zhang <> | Subject | [PATCH] filemap: replace pte_offset_map() with pte_offset_map_nolock() | Date | Wed, 13 Mar 2024 09:29:13 +0800 |
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From: ZhangPeng <zhangpeng362@huawei.com>
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().
Fixes: 58f327f2ce80 ("filemap: avoid unnecessary major faults in filemap_fault()") Suggested-by: David Hildenbrand <david@redhat.com> Signed-off-by: ZhangPeng <zhangpeng362@huawei.com> --- mm/filemap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/filemap.c b/mm/filemap.c index 31ab455c4537..222adac7c9c5 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3207,7 +3207,8 @@ static vm_fault_t filemap_fault_recheck_pte_none(struct vm_fault *vmf) 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; -- 2.25.1
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