From dc677b5f3765cfd0944c8873d1ea57f1a3439676 Mon Sep 17 00:00:00 2001 From: Steve Sistare Date: Wed, 4 Sep 2024 12:41:08 -0700 Subject: [PATCH] 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 Suggested-by: Vivek Kasireddy Cc: David Hildenbrand Cc: Jason Gunthorpe Cc: Matthew Wilcox Cc: Muchun Song Cc: Peter Xu Cc: Signed-off-by: Andrew Morton --- mm/gup.c | 4 +--- mm/memfd.c | 3 +-- 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);