Messages in this thread | | | Date | Wed, 13 Mar 2024 10:22:27 +0100 | Subject | Re: [PATCH] filemap: replace pte_offset_map() with pte_offset_map_nolock() | From | David Hildenbrand <> |
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On 13.03.24 02:29, Peng Zhang wrote: > 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; >
Reviewed-by: David Hildenbrand <david@redhat.com>
-- Cheers,
David / dhildenb
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