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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-Archived-By: 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; 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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