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=1793106314; b=rL/PoCXAJBt0rXpB+qAf1Z5UsjfA32v1Kb8hFDCBkFokfFOmlVl87echA0yhT8RDYAKG 4UY0KZukN0brUa41zwoylh5iKsSCWPx+rZhPCgfLdJ1gIJKuWGkqxg8lWJQ23A2FSkSMV 2LqXcWHoiq4oiI+jm4jDv83Y6PJHgATMWSVBStWXcbP+opgcJaATKbooVYciOWo0fNjyV MO32i3QJYhgPilLGMJWKPi+urpbmSiZcEtJ2lAIob9wK/IyixMCdb/NU7f4Js588c1izn aFD7XF1Y2Xx0fGD9SkQ3o5Z8Hw5xPD/RULaR0mWeTgeYuZcrxd7sID/z+IvnI3ePKQQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793106314; h=Received:DKIM-Signature:From:Date:Subject:MIME-Version:Content-Type: Content-Transfer-Encoding:Message-Id:References:In-Reply-To:To:Cc: X-Mailer:X-Developer-Signature:X-Developer-Key; bh=UKWfg6nXMEPTxXujUYzfp00rWiuxfD1JI+7Tq1SH2b8=; b=3R8WedMX7iD+Mte5i2jmpAYLoMdkeIN1QoEgtTH78nokpSvuiEK//nhEyNgAxo34InSI DYQF8ggJZBphzCHSbQGSqGNBSOqhROIWEksdOuvhku2JLiPRA09dMZ/qhLeaHDCFCSX5q vFCsCK16XaC/MXYwL527H9jsNGJwPXAhPseQPL6Z0oEMIntYb+9XWqbiixleIcTFjmktv dugIggPFw3do3yAFpVXaNRDYl0whp7h1JA2UIkIvUIa6e2RvHaib4omwJOqjGCNNr8h8m 6ZlXQgAVuLIl23TEx/20eJoWoxPgiUx/+iKuxZ8oDJszq/qrajrtFjk5qi+VaiV1gFA== 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=Kp9s8TDt; 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 2A98A60A2634; Tue, 27 Oct 2026 13:05:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Kp9s8TDt Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8EB9E1F01825; Tue, 27 Oct 2026 13:05:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793106314; bh=UKWfg6nXMEPTxXujUYzfp00rWiuxfD1JI+7Tq1SH2b8=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=Kp9s8TDta9bR85RsgT6BZ+ZVbkIwImQjtt+GAaCwxk6heK7vDx653LYrsHkwhXSUM 4eyDrjRmVpk0METZ4Np8f4rqJ9dx8e5+fNkunjb7do92JUh5oOa0Bh7KMHmOEPtSzG 19InT/xTJdtBLOmOs0BdyIY44HXIdGZCTeXIMnSbgGFDBJ/6cZl2ZfdGpNF0kPuKTG hNpwOZj3KGf453gc1NBIevm7pIfxW9qBNQ+B8xnTKsfcHo700lKsM2Cw7Q9uV75Chw 2dYhIBo2Jxz9IIePMFzS5yYnzzlqKPEl1hmSB9MFnfQtuMRyPtkMuxkw6hqQeCJ66I GPqm4S9a76eCw== From: "David Hildenbrand (Arm)" Date: Tue, 27 Oct 2026 14:03:19 +0100 Subject: [PATCH v2 14/14] mm/shmem: fix truncation of files containing only swapin-error markers X-Mailing-List: linux-kernel@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: 7bit Message-Id: <20261027-fixes_shmem-v2-14-86a00952acb9@kernel.org> References: <20261027-fixes_shmem-v2-0-86a00952acb9@kernel.org> In-Reply-To: <20261027-fixes_shmem-v2-0-86a00952acb9@kernel.org> To: Andrew Morton , Gregory Price , Zi Yan , Joshua Hahn , Rakie Kim , Ying Huang , Johannes Weiner , Vladimir Davydov , Michal Hocko , Hugh Dickins , Baolin Wang , Lukas Czerner , Carlos Maiolino , Christian Brauner , Jan Kara , Daniel Verkamp , Jeff Xu , Muchun Song , Oscar Salvador , David Stevens , "Matthew Wilcox (Oracle)" , William Kucharski , Chris Li , Kairui Song , Nhat Pham , Miaohe Lin , Naoya Horiguchi Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, "David Hildenbrand (Arm)" , stable@vger.kernel.org X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1547; i=david@kernel.org; h=from:subject:message-id; bh=i3hN4RE7liAW06y2OgRE+JIRMBR8d+B3ALKw3Lw9zRQ=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLIeLBSKP814sdEoLk21M/PRD6GVt9LFl3/Sibj4n3HZS fvS3A8rOkpZGMQ4GGTFFFmCgu8bvHy5rrbajY8ZZg4rE8gQBi5OAZjIhacM/z0L5r8L6+j0YpNR j6n8mtGpeDq8me9LevOHw392aT2yu83wvyrAf3fGP/n5wa8/6dmeKeruEbjtEct88lbS735FbZd bLAA= X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A It might not be very common, but we can end up with shmem files that are composed only of swapin-error/poison markers. Such markers are not counted in info->alloced. Consequently, shmem_setattr() can skip shmem_truncate_range(), leaving the markers behind. Truncating the file to zero and growing it again will result in reads failing with -EIO instead of returning zeroes. Check whether the mapping contains entries, in addition to info->alloced, before skipping the truncation. Keep the info->alloced check so that shmem_recalc_inode(), called at the end of shmem_undo_range(), can fix up accounting after reclaim has emptied the mapping. Fixes: 6cec2b95dadf ("mm/shmem: fix infinite loop when swap in shmem error at swapoff time") Cc: stable@vger.kernel.org Tested-by: Gregory Price (Meta) Signed-off-by: David Hildenbrand (Arm) --- mm/shmem.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/shmem.c b/mm/shmem.c index 2800dbdf031c1..3c42b4f253b5e 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1591,7 +1591,8 @@ static int shmem_setattr(struct mnt_idmap *idmap, if (oldsize > holebegin) unmap_mapping_range(inode->i_mapping, holebegin, 0, 1); - if (info->alloced) + /* Swapin-error markers are not counted in alloced. */ + if (info->alloced || !mapping_empty(inode->i_mapping)) shmem_truncate_range(inode, newsize, (loff_t)-1); /* unmap again to remove racily COWed private pages */ -- 2.43.0