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mm/hugetlb: simplify refs in memfd_alloc_folio

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commit dc677b5f3765cfd0944c8873d1ea57f1a3439676 upstream.

The folio_try_get in memfd_alloc_folio is not necessary.  Delete it, and
delete the matching folio_put in memfd_pin_folios.  This also avoids
leaking a ref if the memfd_alloc_folio call to hugetlb_add_to_page_cache
fails.  That error path is also broken in a second way -- when its
folio_put causes the ref to become 0, it will implicitly call
free_huge_folio, but then the path *explicitly* calls free_huge_folio.
Delete the latter.

This is a continuation of the fix
  "mm/hugetlb: fix memfd_pin_folios free_huge_pages leak"

[steven.sistare@oracle.com: remove explicit call to free_huge_folio(), per Matthew]
  Link: https://lkml.kernel.org/r/Zti-7nPVMcGgpcbi@casper.infradead.org
  Link: https://lkml.kernel.org/r/1725481920-82506-1-git-send-email-steven.sistare@oracle.com
Link: https://lkml.kernel.org/r/1725478868-61732-1-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>
Suggested-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>
This commit is contained in:
Steve Sistare 2024-09-04 12:41:08 -07:00 committed by Greg Kroah-Hartman
parent e28f39b359
commit 7fab8b3260
2 changed files with 2 additions and 5 deletions
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4
mm/gup.c
View file

@ -3618,7 +3618,7 @@ long memfd_pin_folios(struct file *memfd, loff_t start, loff_t end,
pgoff_t start_idx, end_idx, next_idx;
struct folio *folio = NULL;
struct folio_batch fbatch;
struct hstate *h = NULL;
struct hstate *h;
long ret = -EINVAL;
if (start < 0 || start > end || !max_folios)
@ -3662,8 +3662,6 @@ long memfd_pin_folios(struct file *memfd, loff_t start, loff_t end,
&fbatch);
if (folio) {
folio_put(folio);
if (h)
folio_put(folio);
folio = NULL;
}

3
mm/memfd.c
View file

@ -89,13 +89,12 @@ struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx)
numa_node_id(),
NULL,
gfp_mask);
if (folio && folio_try_get(folio)) {
if (folio) {
err = hugetlb_add_to_page_cache(folio,
memfd->f_mapping,
idx);
if (err) {
folio_put(folio);
free_huge_folio(folio);
return ERR_PTR(err);
}
folio_unlock(folio);