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authorSteve Sistare <steven.sistare@oracle.com>2024-09-04 21:41:08 +0200
committerAndrew Morton <akpm@linux-foundation.org>2024-09-26 23:01:44 +0200
commitdc677b5f3765cfd0944c8873d1ea57f1a3439676 (patch)
tree0984ef6b9be54e5b182541a7a7cd97e21453e4c6
parentmm/gup: fix memfd_pin_folios alloc race panic (diff)
downloadlinux-dc677b5f3765cfd0944c8873d1ea57f1a3439676.tar.xz
linux-dc677b5f3765cfd0944c8873d1ea57f1a3439676.zip
mm/hugetlb: simplify refs in memfd_alloc_folio
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: 89c1905d9c14 ("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>
-rw-r--r--mm/gup.c4
-rw-r--r--mm/memfd.c3
2 files changed, 2 insertions, 5 deletions
diff --git a/mm/gup.c b/mm/gup.c
index 8d9b560a0fec..a82890b46a36 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -3615,7 +3615,7 @@ 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)
@@ -3659,8 +3659,6 @@ 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;
}
diff --git a/mm/memfd.c b/mm/memfd.c
index bcb131db829d..c17c3ea701a1 100644
--- a/mm/memfd.c
+++ b/mm/memfd.c
@@ -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);