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=1793270762; b=XhM3i2ryleUC6EMUt/ZG1Zw8rEk1MAGzd467EHo4SykwmLimI1ZItfaAR2QLTCP2Ygfb H5gqAndBlNAf32faucMnbsCToZIZxhUzPKGMYpo1VrKMFKJAjO9nGuTDwztJz1yOQS4oJ mR3TbVcmcArZ7zaO698tsBK0VZTJoIHv6ShMwJdhanJs79Be0e5OoLSTFqOQr231W0Fft 8UmvuH1a41b/DThCoyMOgj51mtk4IOxuXWjD6hplRJQSaHDF8FD/apKrxzwdJUho2hSEs 3GN/PTPXlspOQoGA3N7L8CVxbA27lIIDekdHc7Yns+EKrOuZ2AkRKhaS2clU6VEpyLA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793270762; 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=F6aNkGCILQejjmcnm5RGfmCiEMne8lGLDKI8m/EHHN0=; b=RcQ9n8EmYHOwR/sPmuLtCOJfJbfaR8c8hBZWGW1gzW3JhfNwbO3esncElO1yzfLlTmN+ tZk+dWWbKaoyu/XZZmpuCWHx9tohgKF4mQeDGGOnfCTv5WfP8n1dcUrdmnf7GLhwlBv6/ zxv3jh7/CmgM2JpNlFL1274jjnFNLe9HL3aD9Gkm7aklQBNJMWwyWdj0wHZfzRpCPH5py rsNXx+kjk6crXxwcXnHMNa/PhDXPL6nkfmojdTC1VloiBOpcaLxR+kYNn3oyI3e7V3CwA J4wrmjtTC6Pxx0gJwQG4U+vpCyeuURsT9cN09f6HTSvKbvojhDd8n3Xn0hYyMQZ1VZA== 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=b1SiGScN; 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 1A5B9606A31D; Thu, 29 Oct 2026 10:46:01 +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=b1SiGScN Received: by smtp.kernel.org (Postfix) with ESMTPSA id 15C281F01825; Thu, 29 Oct 2026 10:45:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793270761; bh=F6aNkGCILQejjmcnm5RGfmCiEMne8lGLDKI8m/EHHN0=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=b1SiGScN5gaMrX3BUT8ZcgSrrzqOsKcKpJtUpEjCDbs07kThIXWnIiQLBOYl23ACS JI562Zwyzpfs14JICCYTVvHrPqNN5A5FpTYtKi+Gm65Kshvq5mXNc02vehV+dblE8i mDrOkRYjdY5hbCijQF+z5j+HmKz3CBMMezGKL3cAJ64RwXX/xQ46wiMnn0YWWqbuJ8 dsErVxADrysN/Ju+UVXwAUP/re9tL+sFscNXtSzro38rZO88XVOB3wSxqXnXNZeNE/ fdJeK1H6KwU7t7q5GKCB5xTnXc/UUndzY7sCzZLXFd6w45nKctrqtleR8Q8ToDzMI/ Zo1+GSjyuZTHw== From: "David Hildenbrand (Arm)" Date: Thu, 29 Oct 2026 11:43:36 +0100 Subject: [PATCH v4 15/15] 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: <20261029-fixes_shmem-v4-15-392fc715d8f6@kernel.org> References: <20261029-fixes_shmem-v4-0-392fc715d8f6@kernel.org> In-Reply-To: <20261029-fixes_shmem-v4-0-392fc715d8f6@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=1609; i=david@kernel.org; h=from:subject:message-id; bh=3cyi7TgGjxMsxAuKMnS5D15fBsBka8mZ87JHY+VoW4U=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLIeK4ffb/+a184UcHL1M8H4rm3yl8JNVmWtO8myKN51w cuvxqnFHaUsDGIcDLJiiixBwfcNXr5cV1vtxscMM4eVCWQIAxenAEykzJLhf9hnqZq2Pz3P3c2U Ln3s/MQmvGOSd+KVIn7uvdw/v7d132Fk+HZzs9urmLyMzFgmx/37/Fc9jpyaNnUG5w9bVefVEbN MWQA= 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) Reviewed-by: Baolin Wang 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 897f19ed0fe3..923957e5e6a2 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1591,7 +1591,8 @@ static int shmem_setattr(const 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