| Message ID | 20241023171236.1122535-1-ziy@nvidia.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: avoid VM_BUG_ON when try to map an anon large folio to zero page. | expand |
On 23.10.24 19:12, Zi Yan wrote: > An anonymous large folio can be split into non order-0 folios, > try_to_map_unused_to_zeropage() should not VM_BUG_ON compound pages but > just return false. This fixes the crash when splitting anonymous large > folios to non order-0 folios. > > Fixes: b1f202060afe ("mm: remap unused subpages to shared zeropage when splitting isolated thp") > Signed-off-by: Zi Yan <ziy@nvidia.com> > --- > mm/migrate.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/migrate.c b/mm/migrate.c > index e950fd62607f..7ffdbe078aa7 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -206,7 +206,8 @@ static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw, > pte_t newpte; > void *addr; > > - VM_BUG_ON_PAGE(PageCompound(page), page); > + if (PageCompound(page)) > + return false; > VM_BUG_ON_PAGE(!PageAnon(page), page); > VM_BUG_ON_PAGE(!PageLocked(page), page); > VM_BUG_ON_PAGE(pte_present(*pvmw->pte), page); Would read nicer in 2024 when working on folios ;) Acked-by: David Hildenbrand <david@redhat.com>
On 23/10/2024 18:12, Zi Yan wrote: > An anonymous large folio can be split into non order-0 folios, > try_to_map_unused_to_zeropage() should not VM_BUG_ON compound pages but > just return false. This fixes the crash when splitting anonymous large > folios to non order-0 folios. > > Fixes: b1f202060afe ("mm: remap unused subpages to shared zeropage when splitting isolated thp") > Signed-off-by: Zi Yan <ziy@nvidia.com> > --- > mm/migrate.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/migrate.c b/mm/migrate.c > index e950fd62607f..7ffdbe078aa7 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -206,7 +206,8 @@ static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw, > pte_t newpte; > void *addr; > > - VM_BUG_ON_PAGE(PageCompound(page), page); > + if (PageCompound(page)) > + return false; > VM_BUG_ON_PAGE(!PageAnon(page), page); > VM_BUG_ON_PAGE(!PageLocked(page), page); > VM_BUG_ON_PAGE(pte_present(*pvmw->pte), page); Thanks for fixing it! Acked-by: Usama Arif <usamaarif642@gmail.com>
diff --git a/mm/migrate.c b/mm/migrate.c index e950fd62607f..7ffdbe078aa7 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -206,7 +206,8 @@ static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw, pte_t newpte; void *addr; - VM_BUG_ON_PAGE(PageCompound(page), page); + if (PageCompound(page)) + return false; VM_BUG_ON_PAGE(!PageAnon(page), page); VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(pte_present(*pvmw->pte), page);
An anonymous large folio can be split into non order-0 folios, try_to_map_unused_to_zeropage() should not VM_BUG_ON compound pages but just return false. This fixes the crash when splitting anonymous large folios to non order-0 folios. Fixes: b1f202060afe ("mm: remap unused subpages to shared zeropage when splitting isolated thp") Signed-off-by: Zi Yan <ziy@nvidia.com> --- mm/migrate.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)