| Message ID | 20240415020821.1152951-1-surenb@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [1/1] userfaultfd: remove WRITE_ONCE when setting folio->index during UFFDIO_MOVE | expand |
On 15.04.24 04:08, Suren Baghdasaryan wrote: > When folio is moved with UFFDIO_MOVE it gets locked before the rmap and > index are modified. Due to the folio lock being already held, WRITE_ONCE() > is not needed when setting the folio index. Remove it. > > Reported-by: Matthew Wilcox <willy@infradead.org> > Signed-off-by: Suren Baghdasaryan <surenb@google.com> > Cc: David Hildenbrand <david@redhat.com> > Cc: Peter Xu <peterx@redhat.com> > Cc: Lokesh Gidra <lokeshgidra@google.com> > --- > mm/huge_memory.c | 2 +- > mm/userfaultfd.c | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 58f2c4745d80..ee12726291f1 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2200,7 +2200,7 @@ int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pm > } > > folio_move_anon_rmap(src_folio, dst_vma); > - WRITE_ONCE(src_folio->index, linear_page_index(dst_vma, dst_addr)); > + src_folio->index = linear_page_index(dst_vma, dst_addr); > > _dst_pmd = mk_huge_pmd(&src_folio->page, dst_vma->vm_page_prot); > /* Follow mremap() behavior and treat the entry dirty after the move */ > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c > index b70618e8dcd2..575ccf90325a 100644 > --- a/mm/userfaultfd.c > +++ b/mm/userfaultfd.c > @@ -1026,7 +1026,7 @@ static int move_present_pte(struct mm_struct *mm, > } > > folio_move_anon_rmap(src_folio, dst_vma); > - WRITE_ONCE(src_folio->index, linear_page_index(dst_vma, dst_addr)); > + src_folio->index = linear_page_index(dst_vma, dst_addr); > > orig_dst_pte = mk_pte(&src_folio->page, dst_vma->vm_page_prot); > /* Follow mremap() behavior and treat the entry dirty after the move */ > > base-commit: 3aec6b2b34e219898883d1e9ea7e911b4d3762a9 Reviewed-by: David Hildenbrand <david@redhat.com>
On Sun, Apr 14, 2024 at 07:08:21PM -0700, Suren Baghdasaryan wrote: > When folio is moved with UFFDIO_MOVE it gets locked before the rmap and > index are modified. Due to the folio lock being already held, WRITE_ONCE() > is not needed when setting the folio index. Remove it. > > Reported-by: Matthew Wilcox <willy@infradead.org> > Signed-off-by: Suren Baghdasaryan <surenb@google.com> > Cc: David Hildenbrand <david@redhat.com> > Cc: Peter Xu <peterx@redhat.com> > Cc: Lokesh Gidra <lokeshgidra@google.com> Reviewed-by: Peter Xu <peterx@redhat.com>
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 58f2c4745d80..ee12726291f1 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2200,7 +2200,7 @@ int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pm } folio_move_anon_rmap(src_folio, dst_vma); - WRITE_ONCE(src_folio->index, linear_page_index(dst_vma, dst_addr)); + src_folio->index = linear_page_index(dst_vma, dst_addr); _dst_pmd = mk_huge_pmd(&src_folio->page, dst_vma->vm_page_prot); /* Follow mremap() behavior and treat the entry dirty after the move */ diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index b70618e8dcd2..575ccf90325a 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -1026,7 +1026,7 @@ static int move_present_pte(struct mm_struct *mm, } folio_move_anon_rmap(src_folio, dst_vma); - WRITE_ONCE(src_folio->index, linear_page_index(dst_vma, dst_addr)); + src_folio->index = linear_page_index(dst_vma, dst_addr); orig_dst_pte = mk_pte(&src_folio->page, dst_vma->vm_page_prot); /* Follow mremap() behavior and treat the entry dirty after the move */
When folio is moved with UFFDIO_MOVE it gets locked before the rmap and index are modified. Due to the folio lock being already held, WRITE_ONCE() is not needed when setting the folio index. Remove it. Reported-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: Suren Baghdasaryan <surenb@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Peter Xu <peterx@redhat.com> Cc: Lokesh Gidra <lokeshgidra@google.com> --- mm/huge_memory.c | 2 +- mm/userfaultfd.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) base-commit: 3aec6b2b34e219898883d1e9ea7e911b4d3762a9