| Message ID | 20230517022115.3033604-3-pcc@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: Fix bug affecting swapping in MTE tagged pages | expand |
On 17.05.23 04:21, Peter Collingbourne wrote: > We would like to move away from requiring architectures to restore > metadata from swap in the set_pte_at() implementation, as this is not only > error-prone but adds complexity to the arch-specific code. This requires > us to call arch_swap_restore() before calling swap_free() whenever pages > are restored from swap. We are currently doing so everywhere except in > unuse_pte(); do so there as well. > > Signed-off-by: Peter Collingbourne <pcc@google.com> > Link: https://linux-review.googlesource.com/id/I68276653e612d64cde271ce1b5a99ae05d6bbc4f > --- > mm/swapfile.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/mm/swapfile.c b/mm/swapfile.c > index 274bbf797480..e9843fadecd6 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -1794,6 +1794,13 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, > goto setpte; > } > > + /* > + * Some architectures may have to restore extra metadata to the page > + * when reading from swap. This metadata may be indexed by swap entry > + * so this must be called before swap_free(). > + */ > + arch_swap_restore(entry, page_folio(page)); > + > /* See do_swap_page() */ > BUG_ON(!PageAnon(page) && PageMappedToDisk(page)); > BUG_ON(PageAnon(page) && PageAnonExclusive(page)); Acked-by: David Hildenbrand <david@redhat.com>
On 17/05/2023 03:21, Peter Collingbourne wrote: > We would like to move away from requiring architectures to restore > metadata from swap in the set_pte_at() implementation, as this is not only > error-prone but adds complexity to the arch-specific code. This requires > us to call arch_swap_restore() before calling swap_free() whenever pages > are restored from swap. We are currently doing so everywhere except in > unuse_pte(); do so there as well. > > Signed-off-by: Peter Collingbourne <pcc@google.com> > Link: https://linux-review.googlesource.com/id/I68276653e612d64cde271ce1b5a99ae05d6bbc4f Reviewed-by: Steven Price <steven.price@arm.com> > --- > mm/swapfile.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/mm/swapfile.c b/mm/swapfile.c > index 274bbf797480..e9843fadecd6 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -1794,6 +1794,13 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, > goto setpte; > } > > + /* > + * Some architectures may have to restore extra metadata to the page > + * when reading from swap. This metadata may be indexed by swap entry > + * so this must be called before swap_free(). > + */ > + arch_swap_restore(entry, page_folio(page)); > + > /* See do_swap_page() */ > BUG_ON(!PageAnon(page) && PageMappedToDisk(page)); > BUG_ON(PageAnon(page) && PageAnonExclusive(page));
On Tue, May 16, 2023 at 07:21:12PM -0700, Peter Collingbourne wrote: > We would like to move away from requiring architectures to restore > metadata from swap in the set_pte_at() implementation, as this is not only > error-prone but adds complexity to the arch-specific code. This requires > us to call arch_swap_restore() before calling swap_free() whenever pages > are restored from swap. We are currently doing so everywhere except in > unuse_pte(); do so there as well. > > Signed-off-by: Peter Collingbourne <pcc@google.com> > Link: https://linux-review.googlesource.com/id/I68276653e612d64cde271ce1b5a99ae05d6bbc4f Acked-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/mm/swapfile.c b/mm/swapfile.c index 274bbf797480..e9843fadecd6 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1794,6 +1794,13 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, goto setpte; } + /* + * Some architectures may have to restore extra metadata to the page + * when reading from swap. This metadata may be indexed by swap entry + * so this must be called before swap_free(). + */ + arch_swap_restore(entry, page_folio(page)); + /* See do_swap_page() */ BUG_ON(!PageAnon(page) && PageMappedToDisk(page)); BUG_ON(PageAnon(page) && PageAnonExclusive(page));
We would like to move away from requiring architectures to restore metadata from swap in the set_pte_at() implementation, as this is not only error-prone but adds complexity to the arch-specific code. This requires us to call arch_swap_restore() before calling swap_free() whenever pages are restored from swap. We are currently doing so everywhere except in unuse_pte(); do so there as well. Signed-off-by: Peter Collingbourne <pcc@google.com> Link: https://linux-review.googlesource.com/id/I68276653e612d64cde271ce1b5a99ae05d6bbc4f --- mm/swapfile.c | 7 +++++++ 1 file changed, 7 insertions(+)