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 X-Spam-Level: X-Spam-Status: No, score=-8.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D18A6C433E0 for ; Tue, 26 Jan 2021 10:18:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9D61122573 for ; Tue, 26 Jan 2021 10:18:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390600AbhAZKRz (ORCPT ); Tue, 26 Jan 2021 05:17:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54600 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731812AbhAYTc4 (ORCPT ); Mon, 25 Jan 2021 14:32:56 -0500 Received: from mail-qt1-x829.google.com (mail-qt1-x829.google.com [IPv6:2607:f8b0:4864:20::829]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32AF3C061573 for ; Mon, 25 Jan 2021 11:32:15 -0800 (PST) Received: by mail-qt1-x829.google.com with SMTP id c12so10567509qtv.5 for ; Mon, 25 Jan 2021 11:32:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=VOhpnXYpKV2hDXXNcrYCS/RM+pFZU4VFPyezZuGNOE0=; b=esIR2J7arBq4Gt+p9Kp5S/ncC/f9faT5SFqcL0Y92sT8pVsloAP67GKjRDWXeei5g9 ki+2Gr3txefIHRAFX1D6tIRKwE3EpEr8npC6DWJLMU4ZwNi6HfBab4/mW8BNWlRECr07 dnjjiHrxIsW8HJH7RtZrZdPUpNP/d5R+7g8c+k/fz59MOVqDt0oozJJ7wJ6OFyjjTLDp E5UyyuuZ9fNjEJMA+1/+C/31DChxtosJaeQt1YY0lE33TlaeCpgr+De/ogSw63HP/5oF ZAOmX1x363hRQS3NVti3PvkbBEdvWTcg6+xETNVNlPv57kAxsR9SoCiZX0dTI4BupAVa ZB+g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=VOhpnXYpKV2hDXXNcrYCS/RM+pFZU4VFPyezZuGNOE0=; b=E9hHL6rP7mGX6RbFb+ns072RJ1L1XdAoevKgXIDpzwaRObWYFgQEIdSs6qSTFkJTee 2MdQKz7K2u/yjsbHfvUkO+SA63PmErU39ckgb0E4cVC0fepNJX7Ms+/tEITwFjC9ybmy lHVX5YTVZQ6EHlBQQckOIf5MdqpFHYaUmrLTLfzUjkTHw+iA8Ny7Rurt/hhwaeENKbk0 HsTC7B87VXGtDLx+JJB9darIYj8rbLipkx+Jvfw3Obs9w6MqSr7bVO43iSLr0Ub/hPDi 9pVw4Lq9KWQVqwEI5P3/+BPKtjvQ2aaEO8pEvOFKIsTOwZQUIEgShTGind0bV3mgeSUg yz2w== X-Gm-Message-State: AOAM533zqFDPiRt4+/38RfPuQ4ATx25d39Qy1BVNT4W9PEE1q9K45Vax gH5FxCsXJ+YKQ0Cvu4lHkuyqZg== X-Google-Smtp-Source: ABdhPJyJbzhJmUoMTfa/94ZpHv9VTdJpXSTGYLtpfKLbczIq4vHQ5lUpPi5DZb1PNqSbTE8+aUdzgw== X-Received: by 2002:aed:31c2:: with SMTP id 60mr1978366qth.218.1611603134482; Mon, 25 Jan 2021 11:32:14 -0800 (PST) Received: from localhost ([2620:10d:c091:480::1:f735]) by smtp.gmail.com with ESMTPSA id a203sm12706672qkb.31.2021.01.25.11.32.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Jan 2021 11:32:13 -0800 (PST) Date: Mon, 25 Jan 2021 14:32:12 -0500 From: Johannes Weiner To: Waiman Long Cc: Andrew Morton , Alex Shi , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/filemap: Adding missing mem_cgroup_uncharge() to __add_to_page_cache_locked() Message-ID: References: <20210125042441.20030-1-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210125042441.20030-1-longman@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jan 24, 2021 at 11:24:41PM -0500, Waiman Long wrote: > The commit 3fea5a499d57 ("mm: memcontrol: convert page > cache to a new mem_cgroup_charge() API") introduced a bug in > __add_to_page_cache_locked() causing the following splat: > > [ 1570.068330] page dumped because: VM_BUG_ON_PAGE(page_memcg(page)) > [ 1570.068333] pages's memcg:ffff8889a4116000 > [ 1570.068343] ------------[ cut here ]------------ > [ 1570.068346] kernel BUG at mm/memcontrol.c:2924! > [ 1570.068355] invalid opcode: 0000 [#1] SMP KASAN PTI > [ 1570.068359] CPU: 35 PID: 12345 Comm: cat Tainted: G S W I 5.11.0-rc4-debug+ #1 > [ 1570.068363] Hardware name: HP HP Z8 G4 Workstation/81C7, BIOS P60 v01.25 12/06/2017 > [ 1570.068365] RIP: 0010:commit_charge+0xf4/0x130 > : > [ 1570.068375] RSP: 0018:ffff8881b38d70e8 EFLAGS: 00010286 > [ 1570.068379] RAX: 0000000000000000 RBX: ffffea00260ddd00 RCX: 0000000000000027 > [ 1570.068382] RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff88907ebe05a8 > [ 1570.068384] RBP: ffffea00260ddd00 R08: ffffed120fd7c0b6 R09: ffffed120fd7c0b6 > [ 1570.068386] R10: ffff88907ebe05ab R11: ffffed120fd7c0b5 R12: ffffea00260ddd38 > [ 1570.068389] R13: ffff8889a4116000 R14: ffff8889a4116000 R15: 0000000000000001 > [ 1570.068391] FS: 00007ff039638680(0000) GS:ffff88907ea00000(0000) knlGS:0000000000000000 > [ 1570.068394] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 1570.068396] CR2: 00007f36f354cc20 CR3: 00000008a0126006 CR4: 00000000007706e0 > [ 1570.068398] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 1570.068400] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 1570.068402] PKRU: 55555554 > [ 1570.068404] Call Trace: > [ 1570.068407] mem_cgroup_charge+0x175/0x770 > [ 1570.068413] __add_to_page_cache_locked+0x712/0xad0 > [ 1570.068439] add_to_page_cache_lru+0xc5/0x1f0 > [ 1570.068461] cachefiles_read_or_alloc_pages+0x895/0x2e10 [cachefiles] > [ 1570.068524] __fscache_read_or_alloc_pages+0x6c0/0xa00 [fscache] > [ 1570.068540] __nfs_readpages_from_fscache+0x16d/0x630 [nfs] > [ 1570.068585] nfs_readpages+0x24e/0x540 [nfs] > [ 1570.068693] read_pages+0x5b1/0xc40 > [ 1570.068711] page_cache_ra_unbounded+0x460/0x750 > [ 1570.068729] generic_file_buffered_read_get_pages+0x290/0x1710 > [ 1570.068756] generic_file_buffered_read+0x2a9/0xc30 > [ 1570.068832] nfs_file_read+0x13f/0x230 [nfs] > [ 1570.068872] new_sync_read+0x3af/0x610 > [ 1570.068901] vfs_read+0x339/0x4b0 > [ 1570.068909] ksys_read+0xf1/0x1c0 > [ 1570.068920] do_syscall_64+0x33/0x40 > [ 1570.068926] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > [ 1570.068930] RIP: 0033:0x7ff039135595 > > Before that commit, there was a try_charge() and commit_charge() > in __add_to_page_cache_locked(). These 2 separated charge functions > were replaced by a single mem_cgroup_charge(). However, it forgot > to add a matching mem_cgroup_uncharge() when the xarray insertion > failed with the page released back to the pool. Fix this by adding a > mem_cgroup_uncharge() call when insertion error happens. > > Fixes: 3fea5a499d57 ("mm: memcontrol: convert page cache to a new mem_cgroup_charge() API") > Signed-off-by: Waiman Long Thanks Waiman. Acked-by: Johannes Weiner Since this crashes the kernel, we should also add Cc: stable@vger.kernel.org # 5.8+