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=1794273664; b=dfCjuZdktO69MeDhHw1e7MGfSz7qjP5P51IX/2Z2mfroxmYCdoDoVSK2td++QZVQGziJ Fvb978A4rS9PsF9jrhmswiyONEmfomQTG8ud+Z6M2u1j7hcei4cYKEk7OskA4TGvMVJ+G 9c3SrcL+Z9hruR79bAIky2B3sRbKy6J5rRwr15QTD/FkOHSsQhLr5pqfEaUlO62H34g+b nYUXfB/g4JS7Mbgb98QcrSWQPA3vsQp8o3c6iWb3fA8pi0dwH+RZnKkfITi7g2aJTiVGj DmzzYoWQGWWW0rdx5qggQ6PYvbGuzHkrz3jCdsG1NrCNOcd9en7HY4vL9+CP7V6irAw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794273664; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=paMSTZy90ULDoKPtkGHNipBJCNLsrFcYuYcT3Zk437k=; b=Y/SRdr16FE71VXqlu36dKLJIg3rkQcZ2yhTa1D5jFuHMKt+7w7bbFVsa1h4zgTtbcgLC e/JNJdczHWfr/9cRlMMu7FkfNmIBtJxbh9L9OsmUqvYLo8IsNlT/pymVDUbBSCcpvB1Vd E6r0qINJGIlI4GnugPIOQbYVAAh4blXZAR8HT2f9ANeIRrOEHlbRT6/6AmS1Juv6gGMDj swOf6HfKqevmc8Nt9mt8paIvKbLcYbMki4dxowARV4apaqacntRk8ytool23shw2tHpt9 ozc1U72b2sxVLzJGm8oyYORdMWgyCZCfYdSZPVk4dwuFd8PJNhF9KlLWcTnSz9PnNGg== 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=gSO1jULe; 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 239F960A2621 for ; Tue, 10 Nov 2026 01:21:04 +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=gSO1jULe Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5A3061F0089F; Tue, 10 Nov 2026 01:21:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794273664; bh=paMSTZy90ULDoKPtkGHNipBJCNLsrFcYuYcT3Zk437k=; h=From:To:Cc:Subject:Date; b=gSO1jULe1sCpQSjQiUmL4g/d5Of33s+UTFOscynDI7JuTwjK/N+QXOUDeqWbsCZzM MX92SKYJObG+IVJYtmk3p8vtnUjhHEmybBVGHe28ld2WkniUiVwUS4iPjG8XvOlAsG htk6CbBwZrFbtZeFw4VElr7MWdpCgMMMGzCdMKyOzpYx/5NuibEuwC2TWaWI3V79Rb Jwbg/Z9fgiR34FUCROlsOzEGmOl9riytKK8ey0FsK9bMh9eNzLIjWGbtIU+3u8itWW 9Cag7bjdIfVrCtUtcnkoctrXmWouN4+DsOj4NyQ+gMN0r4gx8FBwR8o2+iF6XtK+iu 4+mxb0hZBRq5Q== From: Sasha Levin To: david@kernel.org, mason@kernel.org, pratyush@kernel.org, baolin.wang@linux.alibaba.com Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] mm/shmem: make shmem_file() check the file's inode" failed to apply to 5.15-stable tree Date: Mon, 9 Nov 2026 20:21:02 -0500 Message-ID: <20261109202102-failed-5.15-d3710111839d@kernel.org> X-Mailer: git-send-email 2.53.0 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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x d3710111839d11339e414b1bb3fea3d05ab83f6e # git commit -s git send-email --to '' --in-reply-to '20261109202102-failed-5.15-d3710111839d@kernel.org' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From d3710111839d11339e414b1bb3fea3d05ab83f6e Mon Sep 17 00:00:00 2001 From: "David Hildenbrand (Arm)" Date: Sat, 31 Oct 2026 10:39:32 +0100 Subject: [PATCH] mm/shmem: make shmem_file() check the file's inode shmem_file() only checks if file->f_mapping is a shmem mapping. This mapping can belong to another file, however, as with a Coda file backed by a tmpfs container after mmap(). So it does not guarantee that the file inode is an actual shmem inode. Seal handling and memfd preservation use this check before accessing shmem inode state, so they can access an inode of the wrong type. Let's make shmem_file() check the inode's file operations instead, to identify shmem inodes reliably. This will identify regular shmem inodes, including memfds and ordinary tmpfs files, independently of wrapper file operations. Use shmem_mapping() in collapse_file() instead to not change the behavior of collapse_file(): it operates on the page cache and uses mapping->host for shmem inode operations. Focusing on the file does not seem relevant. Fixes: c49fcfcda8b5 ("mm/shmem: update file sealing comments and file checking") Fixes: b3749f174d68 ("mm: memfd_luo: allow preserving memfd") Cc: stable@vger.kernel.org Reported-by: Chris Mason Suggested-by: Pratyush Yadav Reviewed-by: Pratyush Yadav (Google) Link: https://patch.msgid.link/20261031-fixes_core-v3-3-d6437171ecc3@kernel.org Reviewed-by: Baolin Wang Signed-off-by: David Hildenbrand (Arm) --- include/linux/shmem_fs.h | 15 ++++++--------- mm/khugepaged.c | 2 +- mm/shmem.c | 5 +++++ 3 files changed, 12 insertions(+), 10 deletions(-) diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h index a7c7a96a7cbf9..f89b4b1511332 100644 --- a/include/linux/shmem_fs.h +++ b/include/linux/shmem_fs.h @@ -117,8 +117,14 @@ extern unsigned long shmem_get_unmapped_area(struct file *, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags); extern int shmem_lock(struct file *file, int lock, struct ucounts *ucounts); #ifdef CONFIG_SHMEM +bool shmem_file(struct file *file); bool shmem_mapping(const struct address_space *mapping); #else +static inline bool shmem_file(struct file *file) +{ + return false; +} + static inline bool shmem_mapping(const struct address_space *mapping) { return false; @@ -193,15 +199,6 @@ static inline struct page *shmem_read_mapping_page( mapping_gfp_mask(mapping)); } -static inline bool shmem_file(struct file *file) -{ - if (!IS_ENABLED(CONFIG_SHMEM)) - return false; - if (!file || !file->f_mapping) - return false; - return shmem_mapping(file->f_mapping); -} - /* Must be called with inode lock taken exclusive. */ static inline void shmem_freeze(struct inode *inode, bool freeze) { diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 4b71d010b2aff..3a6f4b7b28453 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -2230,6 +2230,7 @@ static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr, struct file *file, pgoff_t start, struct collapse_control *cc) { struct address_space *mapping = file->f_mapping; + const bool is_shmem = shmem_mapping(mapping); struct page *dst; struct folio *folio, *tmp, *new_folio; unsigned long new_pfn = -1; @@ -2238,7 +2239,6 @@ static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr, XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER); enum scan_result result = SCAN_SUCCEED; int nr_none = 0; - bool is_shmem = shmem_file(file); /* * MADV_COLLAPSE ignores shmem huge config, so do not check shmem diff --git a/mm/shmem.c b/mm/shmem.c index 923957e5e6a24..e64704ac72222 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -276,6 +276,11 @@ static const struct vm_operations_struct shmem_vm_ops; static const struct vm_operations_struct shmem_anon_vm_ops; static struct file_system_type shmem_fs_type; +bool shmem_file(struct file *file) +{ + return file && file_inode(file)->i_fop == &shmem_file_operations; +} + bool shmem_mapping(const struct address_space *mapping) { return mapping->a_ops == &shmem_aops; -- 2.53.0