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=1793181439; b=J0oVB9jZkysn5+6MHQRlTsbWy6QMM9Z8sMLt31nmtkDq+7ICWEUPyL7AaFaKUsH2h4NY wFEgxz7bwBEpHL4mVKZV4iQYpRs7+abl38nhc+bgrMWQGr5FWhw9s3Oo/7YWyTy4l5LkW BEQvD18igkJDneCKgtoa6ktNoNVgly/krLof0NY6fW118n62H9LWDxZ4esy5OdbQR8Xw2 eBYfgNR+Axv8x2SMV6CBlMtnGrIdwXdTSbVNFWFDutCkPDWdxWVSURDub9Vxh3jxE3z4Q Qrvu7d69Hu2iU1UZ42jxoj8l6prmajwzmFLDzyHlNaor0L3Mu+dLOKccz9Rr5AMXqGA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793181439; 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=SpR5d9py3XMD/Kz0n214N+JOZVrkF2xRnFstJsjKg1c=; b=4yJx+WVnJbsJn/ZW+vvoq2EPYt8z3mgKwT6mfqWlaveai4NDVa8CjWbaKXnfvjL5Awck JM1/QWuOzIKlKsy2Ij5bNBsbR2yivQ8c9/6sKh3QOx5evt7JOu5R3P7sJjy1TSdUro3DS +yaWn37AevyHsaJt+eeKaMdJZ6OzUsjowUf86MoWKxJZOE8v0IV5KBy5nH9YhhUMQxdy8 PpOIRpEjhIn13UWHA2UIOf8wYv3p77d67bJyOAE09AjltvsChGqRHzxjERzl3GnHXzSyQ GL/90puJgg703QHSQDxcahu3mGdIeiJIFiyO+VR9SNQ+Abl+OhfHJS5Q+84sR3qoWvg== 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=a61qc6fn; 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 C939F606A31A; Wed, 28 Oct 2026 09:57:18 +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=a61qc6fn Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8FCBC1F01829; Wed, 28 Oct 2026 09:57:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793181438; bh=SpR5d9py3XMD/Kz0n214N+JOZVrkF2xRnFstJsjKg1c=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=a61qc6fnEZc3xfx550jc2D95XA3KZeNfm/bD3tKIVBm+O5o6v1jStX9B7HgcN4iq+ +TRzHNpBrQBzOe5eM5GSjvKmBC8PrOtIhuNY9Kf9xZVOcU65M/aneykg/oRvmHOOZt xNgr59mTt/fCCc8G4cUeYGGFR1oul1MpnAnDAO+NCyHQ+HvJupBKhgDn9umn6xVcT4 vif3vXjMAIYShwthmy9MNfWM0uMOOx7gzDrxyDWALD//imvaXzDmvkmmtCGZk9sAIi H8o5lTZ0LHxadSVYVYYcRBD9wnvESt48tHBXS5vAVBLKBvdyrBD8LcR5dm2XympuY8 XS2s/Ze4Frubg== From: "David Hildenbrand (Arm)" Date: Wed, 28 Oct 2026 10:55:13 +0100 Subject: [PATCH v3 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: <20261028-fixes_shmem-v3-15-4ce3baf2db4b@kernel.org> References: <20261028-fixes_shmem-v3-0-4ce3baf2db4b@kernel.org> In-Reply-To: <20261028-fixes_shmem-v3-0-4ce3baf2db4b@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=v1KTmyDVJ6BZ1dQ/IfjBTs7H2skt+1ukgSl8cYUbwr0=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLIeHmt+W2Ky6O7HP87/qpyWdgqc8xUobY1eufv8irofL CYepR63OkpZGMQ4GGTFFFmCgu8bvHy5rrbajY8ZZg4rE8gQBi5OAZjIs0mMDL//7jPQktD//Zxv +gLZ1OrLp3LOfOLkm7Hk1JKfjjGTgu0ZGd5+Z1jHfcxZ2tmq6N99j+1spQJtKQpTuJ0nPBWctWz LJh4A 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 11c3ac313c55..9e51768ef46c 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