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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-Archived-By: 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 X-Rspamd-Queue-Id: 15ADF40002 X-Stat-Signature: w41syqzixjy35795y41jm37re9j3zk5w X-Rspamd-Server: rspam06 X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1793181438-144457 X-HE-Meta: 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 mtjxTPyy CD78gUaj339RqmMW1x/2803S+tvy1JCwh/eHUsDiXkKYFNC+3+obYCD/b+OjOd+MS1U6U73j7OjTJBYOdMQLR3/4B57fG0KzqG06yTegS5POzR6frGQ2EM0twunMsKbwIlQZ4btruHoFrj4oYtrMvmOSzyO4QcIykOzwJkvR+twN/gAq1iEr+Pdn+yrGbJ0lX7jS/9pxrHpvuX7IdQ1Iq9UTM8TgTSxYt2Kk5NffbBPe1SvNyKqXIOUfN2DAlQIOfK5JtdJPVU9wA+MYFTtHoR718iveNS8tcc3FJXeUEHuuwHnKvBa6NysoaO0EYXVzNHIFg7tIVJt+eD8e6OalapMl2YLulGJiTMngv5Kmylvp2AvU1IjKYBBF2yuSAyh+T1vAQZVhR+0PjrfeCSe9M1dgDyg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 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