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b=i7mb91QqykwQoDgzWY9M6nfCGF9CtYL0miYdF1FjCRh0LaqHPRJb//tCmgbKC/umF WgVtyNPI5exENTXXI6xwP2+99qN9n+9hrWnjuf1xfV+BNi2cKGams7B+AsxNWyQxiR bJlInhJx9qAq2tEv93oHYdzY4dxGjx+gnA1bBqwYt1dlsykhpcsPO3BNK+7Mvmq4lk 37s7HkIWBH3DHE+TPd4uELH3PWaS4exrVNnGexWjkfvysOXcvx4L3B1Apbqq+jSy/c 3A0lxJUmTALBaoajpr2hTpbrtd1EBQjh9efnquvyc7chjrx5YlNdy/j8/JRjAnLKB0 LuVgsqs5p31bw== From: "David Hildenbrand (Arm)" Date: Mon, 26 Oct 2026 10:40:49 +0100 Subject: [PATCH 16/16] 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: <20261026-fixes_shmem-v1-16-703206d5fa0c@kernel.org> References: <20261026-fixes_shmem-v1-0-703206d5fa0c@kernel.org> In-Reply-To: <20261026-fixes_shmem-v1-0-703206d5fa0c@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=1500; i=david@kernel.org; h=from:subject:message-id; bh=IWKD21922t1O1049MId3yRDZkDpskSIBwZEf2NiLDd8=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLLuK0h0lVU6Mlkwfkq8/3HWSbnEHS8VvvN47eBda8snY nvuQMinjlIWBjEOBlkxRZag4PsGL1+uq61242OGmcPKBDKEgYtTACayKYKRYd722qp1zevZ/C8e 8VttVznfrGVK/cnM5SvPs0VZ1men+zEy/OSZbHT2zvkO5zar7b931FU7pyTu/2a9sV3p9sQd2SK /mAE= X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 18246C0004 X-Spam-Status: No, score=-19.1 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-Stat-Signature: 94s1ezeoqd3ac4xsao468mxkaojob574 X-HE-Tag: 1793007766-827343 X-HE-Meta: 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 p/OeD6n/ 99DzswqnRBKVSrvkHDDCa0KoRSRqp6SYEIQqGXYvK1jwgatwmVSOQfd42jiqEUQp6d3V4k5o+i+AAWqU3JKe4nx0cZhDvfMwcSBltJmX95a1xI2u3Ld1LxipTsms5jAY7FtHNU31T49VZ0F2swWYhSprV9PC4gYiKldq3AVglxd+oCwwyP2R9Nuot04KmAZWWdmZ93netpqShev6iqNu3f7A39OngQi3k7z7r16JuoYfbx6QiHP1t6eiH7BSNW/yeA5a9+LI1y/baPxAzUR4CsWsd5uO4ph+hXsaX1oPDxbUMf+xt7M5C8YVwdIytPPkaO88Z 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 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 f5b5c9a312c53..45f6c34f161e4 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1602,7 +1602,8 @@ 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