From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794632690; b=PS+gvuJRPiLpmcKCWAtL50DuJXhK0BajW4aNaj7Gm7eO/c8dqE/s6ToJzRxqeQnrKszt BMC5Renp9fCqujaza20IfWs1rNy+d15VaMRsE4A6cdBsUj4cluuFW89Y68UK7ZsJwue0/ UuneBQD80nmZsbkPfWLSPWpZ4cH3BH4iGrfb8shX8TE3xcrkihXVYb8CWg6b0R1atxYa+ gtNizNzWZp7aYYVnlO7EmrMNYmHEJdvxWJJfZHFqDLl9YIlskBo/0bblLSKKGUW9uh3/K tE+GCfM35jSXaTrPzHmihR7tI0NG+8JRCOtNAZPuEiCA94RjoPjMDDWdz9BXTOziYyA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794632690; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=zXWA4Qn5OUCZBV4Ixxiop+LSnnrJCJE7w3Q5gsg9qJY=; b=W1tgkPUPWIEnQD5o5pL2JfTZ0NZg4EQ3PdksIJTCWRwlDFam2fnVs4hOgaTAzWkW8vR7 QJDHcCUx8KGqv3hF4l+GWMQeTWKP2Ipb7XOdKnFVIhKLlxrb7pvgLK6Y+D3Lpo0GvLr9e eVtDFmNEx7Ed/SvJ7lHeg+oHsN8PQqIeaxWStj9c/trrKnalWls2VanSV5hZsHpq7zhsV jP/5dzFzBYrWMwPLGZZc7SILgSTn2dG4g0Ov0iY7w1WcLWZPT/M+x6y4LfTqBJ9y81P3o YSvl7Q0pB0Bb5DsNwXvJC8i6tihdmZapE0mNOw1XhUWTDFkkDFu6K9qLr1qm1jy9OYg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=B3Fl44Cy; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AA9D9606A327 for ; Sat, 14 Nov 2026 05:04:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=B3Fl44Cy Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73F6F1F000C4; Sat, 14 Nov 2026 05:04:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794632690; bh=zXWA4Qn5OUCZBV4Ixxiop+LSnnrJCJE7w3Q5gsg9qJY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=B3Fl44CymFEcziKu+r+k9+pQm5ghnxZILXBw0EQsgzwVYZPrDikK+Emj35otoFXwo WnfODPnfVEAqn+UtOdugfWJRxwn7QuiFKuHi+Ig5F8Z22wDLN5ell7cxhF07B/q0OS M/fDBeesxo8jMcCUHG6dinbcPeuXBQjRJd0+OllHRe6YpYa4LFQu8n46UUWfRfJGNp jIqq5FhDUOZp3MwNCCwP9z7iiN8pt9nG1V3NpqCUgtwBI1pUII5lNMccRVrJI0aIuJ fXA3XV/XTozOmknh4hiZBhBaWyV9C5KVQL+AvTTi8mDdXvVXJ4/tV5HJTYqHrECsNk 9m4oNFe9usWlQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Josef Bacik , Rik van Riel , Muhammad Usama Anjum , Zi Yan , "David Hildenbrand (Arm)" , Sasha Levin Subject: [PATCH 5.10.y] mm/filemap: read mapping->a_ops->free_folio under i_lock Date: Sat, 14 Nov 2026 00:04:48 -0500 Message-ID: <20261114050437.3014185-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261109202614-failed-5.10-dc24e273244e@kernel.org> References: <20261109202614-failed-5.10-dc24e273244e@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Josef Bacik [ Upstream commit dc24e273244e9d712257d5a6c20a32c7f5ca84e6 ] memory_failure() -> ... -> filemap_remove_folio() can read mapping->a_ops after the inode has been freed. Once the folio is deleted from the pagecache it no longer pins the mapping, so after i_lock is dropped e.g., a concurrent final iput() can evict and free the inode before filemap_free_folio() looks up mapping->a_ops->free_folio. Most callers hold a reference on the inode, but not all. Documentation/filesystems/vfs.rst explicitly states that ->free_folio() must not assume the original address_space mapping still exists. Fix it by loading ->free_folio while i_lock is still held, similar to what folio_unmap_invalidate() does. Inline filemap_free_folio() into its remaining caller such that delete_from_page_cache_batch() also just loads the callback before dropping the i_lock. The bug was found by code inspection and has not been reproduced. Fix generated by an LLM and sent by Josef Bacik in private. Fixes: 59c66c5f8c4f ("mm: factor out page cache page freeing into a separate function") Cc: stable@vger.kernel.org Signed-off-by: Josef Bacik [ david: get rid of filemap_free_folio() entirely; improve patch description ] Reviewed-by: Rik van Riel Tested-by: Muhammad Usama Anjum Reviewed-by: Zi Yan Link: https://patch.msgid.link/20261031-fixes_core-v3-6-d6437171ecc3@kernel.org Signed-off-by: David Hildenbrand (Arm) [ sashal: adapted free_folio handling to freepage with callback lookup protected by i_pages instead of i_lock ] Signed-off-by: Sasha Levin --- mm/filemap.c | 44 ++++++++++++++++++++++++-------------------- 1 file changed, 24 insertions(+), 20 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index b98af5680bb9c..f8a28274828f3 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -239,23 +239,6 @@ void __delete_from_page_cache(struct page *page, void *shadow) page_cache_delete(mapping, page, shadow); } -static void page_cache_free_page(struct address_space *mapping, - struct page *page) -{ - void (*freepage)(struct page *); - - freepage = mapping->a_ops->freepage; - if (freepage) - freepage(page); - - if (PageTransHuge(page) && !PageHuge(page)) { - page_ref_sub(page, thp_nr_pages(page)); - VM_BUG_ON_PAGE(page_count(page) <= 0, page); - } else { - put_page(page); - } -} - /** * delete_from_page_cache - delete page from page cache * @page: the page which the kernel is trying to remove from page cache @@ -267,14 +250,23 @@ static void page_cache_free_page(struct address_space *mapping, void delete_from_page_cache(struct page *page) { struct address_space *mapping = page_mapping(page); + void (*freepage)(struct page *page); unsigned long flags; BUG_ON(!PageLocked(page)); xa_lock_irqsave(&mapping->i_pages, flags); __delete_from_page_cache(page, NULL); + freepage = mapping->a_ops->freepage; xa_unlock_irqrestore(&mapping->i_pages, flags); - page_cache_free_page(mapping, page); + if (freepage) + freepage(page); + if (PageTransHuge(page) && !PageHuge(page)) { + page_ref_sub(page, thp_nr_pages(page)); + VM_BUG_ON_PAGE(page_count(page) <= 0, page); + } else { + put_page(page); + } } EXPORT_SYMBOL(delete_from_page_cache); @@ -343,6 +335,7 @@ static void page_cache_delete_batch(struct address_space *mapping, void delete_from_page_cache_batch(struct address_space *mapping, struct pagevec *pvec) { + void (*freepage)(struct page *page); int i; unsigned long flags; @@ -356,10 +349,21 @@ void delete_from_page_cache_batch(struct address_space *mapping, unaccount_page_cache_page(mapping, pvec->pages[i]); } page_cache_delete_batch(mapping, pvec); + freepage = mapping->a_ops->freepage; xa_unlock_irqrestore(&mapping->i_pages, flags); - for (i = 0; i < pagevec_count(pvec); i++) - page_cache_free_page(mapping, pvec->pages[i]); + for (i = 0; i < pagevec_count(pvec); i++) { + struct page *page = pvec->pages[i]; + + if (freepage) + freepage(page); + if (PageTransHuge(page) && !PageHuge(page)) { + page_ref_sub(page, thp_nr_pages(page)); + VM_BUG_ON_PAGE(page_count(page) <= 0, page); + } else { + put_page(page); + } + } } int filemap_check_errors(struct address_space *mapping) -- 2.53.0