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Received: from willy by casper.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1slwDT-00000001LSc-3cDI; Wed, 04 Sep 2024 20:03:00 +0000 Date: Wed, 4 Sep 2024 21:02:59 +0100 From: Matthew Wilcox To: Steve Sistare Cc: linux-mm@kvack.org, Vivek Kasireddy , Muchun Song , Andrew Morton , Peter Xu , David Hildenbrand , Jason Gunthorpe Subject: Re: [PATCH] mm/hugetlb: simplify refs in memfd_alloc_folio Message-ID: References: <1725478868-61732-1-git-send-email-steven.sistare@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1725478868-61732-1-git-send-email-steven.sistare@oracle.com> X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 20146160024 X-Stat-Signature: nmr7akimf46576mb6x7oobgr8j1xxk4t X-HE-Tag: 1725480182-896567 X-HE-Meta: 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 gDZqkcRf e/tws0dg9Ar/N41h4pQH5vqbb+Wc+hVOEuzqGBHxxxlp9msOVYy38o6HCvYJGUd0KROoBSy12ylxdrkGKxme87ek3VxS7HDi8FNK20tULjUoReq48VGpmHZMmld1EkD6atLNvgLPtV1ZHjRuoaxUZlMNXXuOilViu0R510AYHzYqy0PlUPbJ8x1OkHyJp6o4uDC9w7SoBnNgIhiete3HwdJEDsnb8KPzW8mRfXI1ttDXQSPw7NhqzWmXV9d7wWMNOpurLSJfhOLqwgrFuW68gQhHBXZlD2PJzGD3SJu1uT7pKSkDEgTG+RthjOPlWUdG13ltC X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Sep 04, 2024 at 12:41:08PM -0700, Steve Sistare wrote: > 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, which would otherwise need an additional folio_put. This is a > continuation of the fix > "mm/hugetlb: fix memfd_pin_folios free_huge_pages leak" I think you're right, but don't we also need to get rid of the folio_put() call in the 'if (err)' case after calling hugetlb_add_to_page_cache()? > Fixes: 89c1905d9c14 ("mm/gup: introduce memfd_pin_folios() for pinning memfd folios") > > Suggested-by: Vivek Kasireddy > Signed-off-by: Steve Sistare > --- > mm/gup.c | 4 +--- > mm/memfd.c | 2 +- > 2 files changed, 2 insertions(+), 4 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index bccabaa..947881ff 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -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; > } > > diff --git a/mm/memfd.c b/mm/memfd.c > index bcb131d..f715301 100644 > --- a/mm/memfd.c > +++ b/mm/memfd.c > @@ -89,7 +89,7 @@ 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); > -- > 1.8.3.1 >