From patchwork Sat Feb 22 16:08:47 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kemeng Shi X-Patchwork-Id: 13986549 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 50E01C021B5 for ; Sat, 22 Feb 2025 07:12:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 43AC56B0089; Sat, 22 Feb 2025 02:12:39 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 058106B0092; Sat, 22 Feb 2025 02:12:38 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BF9B86B0085; Sat, 22 Feb 2025 02:12:38 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 780946B0089 for ; Sat, 22 Feb 2025 02:12:38 -0500 (EST) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 220B11A082C for ; Sat, 22 Feb 2025 07:12:38 +0000 (UTC) X-FDA: 83146712796.21.49F5FC7 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) by imf22.hostedemail.com (Postfix) with ESMTP id 1AB48C0007 for ; Sat, 22 Feb 2025 07:12:33 +0000 (UTC) Authentication-Results: imf22.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf22.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=1740208356; 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=rX4/pCbzu6P9xmEoDSdy+9bsmGQtLEgH11a3wQJfyIk=; b=R0pbvUMsMBNTx4EweYG1sP3+J7GPPZ7indxTOLC3HUEnccQ9NHCwouiK/w1GqRHEAPIQEK Q3w6FQXgrWF/YrNIfesHkKtkU9jzVTaYlCFAHEUWxYmWz7GTQZPmwJG7OUpOIEOxIdZMmZ hJtDPUTiue50Iyn42PczHNhTVAQkog8= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf22.hostedemail.com: domain of shikemeng@huaweicloud.com designates 45.249.212.51 as permitted sender) smtp.mailfrom=shikemeng@huaweicloud.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1740208356; a=rsa-sha256; cv=none; b=xisXubFzw+ash3A+RFy7z4XpNvfSby5QnRChBF3wi5HE9HbjjJcWxyf6UcJpC6h4mpj3nH /HnsA1CPIMbb8V8cyDXY9a+N0BN6VHI8lSFEUKKLzCcCAkgd0guM7DZ40m+8BuhEsY+BN0 jmNjYlA8jVTv6F28MEeu9KmvBUnRUos= Received: from mail.maildlp.com (unknown [172.19.163.216]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4Z0J8r5WGjz4f3jtD for ; Sat, 22 Feb 2025 15:12:12 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.75]) by mail.maildlp.com (Postfix) with ESMTP id 271C31A0E98 for ; Sat, 22 Feb 2025 15:12:29 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.101.6]) by APP2 (Coremail) with SMTP id Syh0CgBHBWjaeLlnrTsjEg--.26688S5; Sat, 22 Feb 2025 15:12:29 +0800 (CST) From: Kemeng Shi To: akpm@linux-foundation.org, kasong@tencent.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 3/6] mm, swap: avoid BUG_ON in relocate_cluster() Date: Sun, 23 Feb 2025 00:08:47 +0800 Message-Id: <20250222160850.505274-4-shikemeng@huaweicloud.com> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20250222160850.505274-1-shikemeng@huaweicloud.com> References: <20250222160850.505274-1-shikemeng@huaweicloud.com> MIME-Version: 1.0 X-CM-TRANSID: Syh0CgBHBWjaeLlnrTsjEg--.26688S5 X-Coremail-Antispam: 1UD129KBjvJXoW7Ar17GFW7JF45GrW5Cr1xZrb_yoW8XFW3pr 1fKF98tF4xtr4kGw45A3Z3JayrGw40gry5Gay3Xr1fCasxZr4xKFyvyr9avr98GF4kCa4D ZF1DKa4xuFn8A3JanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUB0b4IE77IF4wAFF20E14v26ryj6rWUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M280x2IEY4vEnII2IxkI6r1a6r45M2 8IrcIa0xkI8VA2jI8067AKxVWUWwA2048vs2IY020Ec7CjxVAFwI0_Gr0_Xr1l8cAvFVAK 0II2c7xJM28CjxkF64kEwVA0rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVWDJVCq3wA2z4 x0Y4vE2Ix0cI8IcVCY1x0267AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l 84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I 8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AK xVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41l42xK82IYc2Ij64 vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8G jcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r126r1DMIIYrxkI7VAKI48JMIIF0xvE2I x0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMIIF0xvE42xK 8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I 0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjxU3G-eDUUUU X-CM-SenderInfo: 5vklyvpphqwq5kxd4v5lfo033gof0z/ X-Rspam-User: X-Stat-Signature: zy39a1ezaigxjnrm3k9jdqxn7xkzfgi6 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 1AB48C0007 X-HE-Tag: 1740208353-580998 X-HE-Meta: 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 R+hJmpZ2 KlfG+vHvxGB8TnkXtuGIP9Ob7M5Q13B4Qu5zpE/HFpn00k9YXOr/1u73qZvFWdWTDiHMN0/vXPqCVkR55BLaPi8Nw1kOI8wJhwkf3PifhMe1B7Jc7GEwwDmn8Wn8AXl0mGimD6QhPCC941vFbh2D/REEfziNtMPVKNwlZP6nxJ2AD1GKV7pFzb5xL0gCYoFSwcYQGMLlDgz9R6jHM7hrZAPNyGw== 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 allocation is racy with swapoff, we may call free_cluster for cluster already in free list and trigger bug on as following: Allocation Swapoff cluster_alloc_swap_entry ... /* may get a free cluster with offset */ offset = xxx; if (offset) ci = lock_cluster(si, offset); ... del_from_avail_list(p, true); si->flags &= ~SWP_WRITEOK; alloc_swap_scan_cluster(si, ci, ...) ... /* failed to alloc entry from free entry */ if (!cluster_alloc_range(...)) break; ... /* add back a free cluster */ relocate_cluster(si, ci); if (!ci->count) free_cluster(si, ci); VM_BUG_ON(ci->flags == CLUSTER_FLAG_FREE); Despite bug_on could be triggered, call free_cluster() for free cluster only move cluster to tail of list and should be fine. Check cluster is not free before calling free_cluster() in relocate_cluster() to avoid bug_on. Fixes: 3b644773eefda ("mm, swap: reduce contention on device lock") Signed-off-by: Kemeng Shi Reviewed-by: Kairui Song --- mm/swapfile.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index 425126c0a07d..fc45b9d56639 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -653,7 +653,8 @@ static void relocate_cluster(struct swap_info_struct *si, return; if (!ci->count) { - free_cluster(si, ci); + if (ci->flags != CLUSTER_FLAG_FREE) + free_cluster(si, ci); } else if (ci->count != SWAPFILE_CLUSTER) { if (ci->flags != CLUSTER_FLAG_FRAG) move_cluster(si, ci, &si->frag_clusters[ci->order],