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mm/gup: fix memfd_pin_folios hugetlb page allocation

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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@oracle.com
Fixes: 89c1905d9c ("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>
This commit is contained in:
Steve Sistare 2024-09-03 07:25:20 -07:00 committed by Andrew Morton
parent 26a8ea8092
commit 9289f020da
1 changed files with 7 additions and 3 deletions
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10
mm/memfd.c
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@ -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);