From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9404BC3ABC9 for ; Fri, 16 May 2025 08:15:42 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E347C6B00F2; Fri, 16 May 2025 04:15:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A4CB06B00FD; Fri, 16 May 2025 04:15:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4753D6B00FA; Fri, 16 May 2025 04:15:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id C94256B00F8 for ; Fri, 16 May 2025 04:15:34 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 89516161A4A for ; Fri, 16 May 2025 08:15:35 +0000 (UTC) X-FDA: 83448061830.13.73FFFA8 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) by imf14.hostedemail.com (Postfix) with ESMTP id B35ED10000C for ; Fri, 16 May 2025 08:15:32 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf14.hostedemail.com: domain of shikemeng@huaweicloud.com designates 45.249.212.51 as permitted sender) smtp.mailfrom=shikemeng@huaweicloud.com ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf14.hostedemail.com: domain of shikemeng@huaweicloud.com designates 45.249.212.51 as permitted sender) smtp.mailfrom=shikemeng@huaweicloud.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1747383333; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=kKTFSDPP2uwMR8x4KrgOtWh0v01bKqx8UyXfQXZpq6U=; b=hTP2gmgCqIzLb5zKZ1/rEpczQ014ka0MCUNtp4SUDoRAtyvG0wnR9l82W3/IOGeuh6tVO5 w2r826e/VbMQ+rIDSTccLRVvRGiAKmLU/WhyZSAWKKYladMv98rbctE7gNKz5jEP2bUpH1 qkc4iol4mK4XPh1KBm5mOGfGW96lUjk= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1747383333; a=rsa-sha256; cv=none; b=EqNUDRYxnjzr/mkjO1SoiDaRXh81SXsMHXCrkOgRMTMdHoiz3p2w7ecTxktKaAK9wRNYnb JDaSh+qECBmZusF1Iwu2n1ppeqZm4krc5hqgUVcXMZwAjTUno3WP0ILOFQ6WtHzDIzIDtK QEcq5htWPQ/u3oVv0yN1FIfOSucUAAc= Received: from mail.maildlp.com (unknown [172.19.163.235]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4ZzKdY5dzBzYQv6p for ; Fri, 16 May 2025 16:15:29 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.252]) by mail.maildlp.com (Postfix) with ESMTP id 0EE8E1A0B54 for ; Fri, 16 May 2025 16:15:29 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.101.6]) by APP3 (Coremail) with SMTP id _Ch0CgDnOsUe9CZo9fSDMQ--.49450S5; Fri, 16 May 2025 16:15:28 +0800 (CST) From: Kemeng Shi To: hughd@google.com, baolin.wang@linux.alibaba.com, akpm@linux-foundation.org Cc: ryncsn@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 3/5] mm/shmem: Fix potential dead loop in shmem_unuse() Date: Sat, 17 May 2025 01:09:37 +0800 Message-Id: <20250516170939.965736-4-shikemeng@huaweicloud.com> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20250516170939.965736-1-shikemeng@huaweicloud.com> References: <20250516170939.965736-1-shikemeng@huaweicloud.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:_Ch0CgDnOsUe9CZo9fSDMQ--.49450S5 X-Coremail-Antispam: 1UD129KBjvJXoW7ZFWfWrWDtw45Ar4xGr43trb_yoW8ZF4rpr n8u3srtrWrZrykGFWxtF18urWYqw4SgF4Utay3C3Z5A3WUtr42grnFqryUu393CrZ8XFW3 tFn29ry3Aa1vyrJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPFb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M280x2IEY4vEnII2IxkI6r1a6r45M2 8IrcIa0xkI8VA2jI8067AKxVWUWwA2048vs2IY020Ec7CjxVAFwI0_Gr0_Xr1l8cAvFVAK 0II2c7xJM28CjxkF64kEwVA0rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVWDJVCq3wA2z4 x0Y4vE2Ix0cI8IcVCY1x0267AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l 84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I 8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AK xVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lc7CjxVAaw2AFwI 0_JF0_Jw1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG 67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r126r1DMI IYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E 14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJV W8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjxUa75r DUUUU X-CM-SenderInfo: 5vklyvpphqwq5kxd4v5lfo033gof0z/ X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: B35ED10000C X-Stat-Signature: ntedyd4msjn41hp7qxezfs5utuxic938 X-Rspam-User: X-HE-Tag: 1747383332-347932 X-HE-Meta: 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 XI7MgVxC RdruUpd0FfTVxKCoYDNa6M8yT/ieBvgKObFFQoc0BJ+Pv+wdpC+lbBg2mRJT2uonJ01edO/bGGjblB9RcqWxru9Stzb0AsyuhxkpoqSvURH8smRMJNHUmczaEbWwx5jHxtpCS1eKdfklPlvinoKG3LT6LFaDoZ2M4DVlgxVCQ/jFyeSUi0z04i7GggVvbVZE4QndA3ymJZCLtBHYT1Pepd0MrCj6iX8PG1ATOqrkay8vcgwZVlpCsC8q2Ow== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: If multi shmem_unuse() for different swap type is called concurrently, a dead loop could occur as following: shmem_unuse(typeA) shmem_unuse(typeB) mutex_lock(&shmem_swaplist_mutex) list_for_each_entry_safe(info, next, ...) ... mutex_unlock(&shmem_swaplist_mutex) /* info->swapped may drop to 0 */ shmem_unuse_inode(&info->vfs_inode, type) mutex_lock(&shmem_swaplist_mutex) list_for_each_entry(info, next, ...) if (!info->swapped) list_del_init(&info->swaplist) ... mutex_unlock(&shmem_swaplist_mutex) mutex_lock(&shmem_swaplist_mutex) /* iterate with offlist entry and encounter a dead loop */ next = list_next_entry(info, swaplist); ... Restart the iteration if the inode is already off shmem_swaplist list to fix the issue. Fixes: b56a2d8af9147 ("mm: rid swapoff of quadratic complexity") Signed-off-by: Kemeng Shi Reviewed-by: Baolin Wang --- mm/shmem.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index 495e661eb8bb..aeeddf612baa 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1505,6 +1505,7 @@ int shmem_unuse(unsigned int type) return 0; mutex_lock(&shmem_swaplist_mutex); +start_over: list_for_each_entry_safe(info, next, &shmem_swaplist, swaplist) { if (!info->swapped) { list_del_init(&info->swaplist); @@ -1523,13 +1524,15 @@ int shmem_unuse(unsigned int type) cond_resched(); mutex_lock(&shmem_swaplist_mutex); - next = list_next_entry(info, swaplist); - if (!info->swapped) - list_del_init(&info->swaplist); if (atomic_dec_and_test(&info->stop_eviction)) wake_up_var(&info->stop_eviction); if (error) break; + if (list_empty(&info->swaplist)) + goto start_over; + next = list_next_entry(info, swaplist); + if (!info->swapped) + list_del_init(&info->swaplist); } mutex_unlock(&shmem_swaplist_mutex); -- 2.30.0