6.11-stable review patch. If anyone has any objections, please let me know.
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From: Steve Sistare steven.sistare@oracle.com
commit 9289f020da47ef04b28865589eeee3d56d4bafea upstream.
When memfd_pin_folios -> memfd_alloc_folio creates a hugetlb page, the index is wrong. The subsequent call to filemap_get_folios_contig thus cannot find it, and fails, and memfd_pin_folios loops forever. To fix, adjust the index for the huge_page_order.
memfd_alloc_folio also forgets to unlock the folio, so the next touch of the page calls hugetlb_fault which blocks forever trying to take the lock. Unlock it.
Link: https://lkml.kernel.org/r/1725373521-451395-5-git-send-email-steven.sistare@... Fixes: 89c1905d9c14 ("mm/gup: introduce memfd_pin_folios() for pinning memfd folios") Signed-off-by: Steve Sistare steven.sistare@oracle.com Acked-by: Vivek Kasireddy vivek.kasireddy@intel.com Cc: David Hildenbrand david@redhat.com Cc: Jason Gunthorpe jgg@nvidia.com Cc: Matthew Wilcox willy@infradead.org Cc: Muchun Song muchun.song@linux.dev Cc: Peter Xu peterx@redhat.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/memfd.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/mm/memfd.c b/mm/memfd.c index bfe0e7189a37..bcb131db829d 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -79,10 +79,13 @@ struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx) * alloc from. Also, the folio will be pinned for an indefinite * amount of time, so it is not expected to be migrated away. */ - gfp_mask = htlb_alloc_mask(hstate_file(memfd)); - gfp_mask &= ~(__GFP_HIGHMEM | __GFP_MOVABLE); + struct hstate *h = hstate_file(memfd);
- folio = alloc_hugetlb_folio_reserve(hstate_file(memfd), + gfp_mask = htlb_alloc_mask(h); + gfp_mask &= ~(__GFP_HIGHMEM | __GFP_MOVABLE); + idx >>= huge_page_order(h); + + folio = alloc_hugetlb_folio_reserve(h, numa_node_id(), NULL, gfp_mask); @@ -95,6 +98,7 @@ struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx) free_huge_folio(folio); return ERR_PTR(err); } + folio_unlock(folio); return folio; } return ERR_PTR(-ENOMEM);