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=-17.5 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,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 29F36C433DB for ; Mon, 25 Jan 2021 15:40:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E3354230FE for ; Mon, 25 Jan 2021 15:40:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730161AbhAYPkj (ORCPT ); Mon, 25 Jan 2021 10:40:39 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:59920 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729875AbhAYPhY (ORCPT ); Mon, 25 Jan 2021 10:37:24 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611588957; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0PK5xHUfwoLtHAFk0lU4eMj70hhnXpd2uUmbVV3+Syg=; b=FwEZiNYfZJmm72k4d6OTRL5yl5sOATM+HZYf8WduyzL1OKdjBGj1qZjJD3XHkzDAhQDD+/ FYeKanyOYaA3rhLvAj0EHAqVrhsDNh1cWtACKhucfrHGB9JXCbN4QbVuVp4bpRMRcr5wGN YTgqe6BjqecCeIKgHyX1gRppjD8beng= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-471-iaAfsTTHPpmJARjRl86SIQ-1; Mon, 25 Jan 2021 10:35:53 -0500 X-MC-Unique: iaAfsTTHPpmJARjRl86SIQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5C44B100E33E; Mon, 25 Jan 2021 15:35:51 +0000 (UTC) Received: from llong.remote.csb (ovpn-117-163.rdu2.redhat.com [10.10.117.163]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1D10F10016FA; Mon, 25 Jan 2021 15:35:50 +0000 (UTC) Subject: Re: [PATCH] mm/filemap: Adding missing mem_cgroup_uncharge() to __add_to_page_cache_locked() To: Muchun Song Cc: Andrew Morton , Johannes Weiner , Alex Shi , linux-mm@kvack.org, linux-kernel References: <20210125042441.20030-1-longman@redhat.com> From: Waiman Long Organization: Red Hat Message-ID: Date: Mon, 25 Jan 2021 10:35:49 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/25/21 3:07 AM, Muchun Song wrote: > On Mon, Jan 25, 2021 at 12:29 PM 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 >> --- >> mm/filemap.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/mm/filemap.c b/mm/filemap.c >> index 5c9d564317a5..aa0e0fb04670 100644 >> --- a/mm/filemap.c >> +++ b/mm/filemap.c >> @@ -835,6 +835,7 @@ noinline int __add_to_page_cache_locked(struct page *page, >> XA_STATE(xas, &mapping->i_pages, offset); >> int huge = PageHuge(page); >> int error; >> + bool charged = false; >> >> VM_BUG_ON_PAGE(!PageLocked(page), page); >> VM_BUG_ON_PAGE(PageSwapBacked(page), page); >> @@ -848,6 +849,7 @@ noinline int __add_to_page_cache_locked(struct page *page, >> error = mem_cgroup_charge(page, current->mm, gfp); >> if (error) >> goto error; >> + charged = true; >> } >> >> gfp &= GFP_RECLAIM_MASK; >> @@ -896,6 +898,8 @@ noinline int __add_to_page_cache_locked(struct page *page, >> >> if (xas_error(&xas)) { >> error = xas_error(&xas); >> + if (charged) > Can "if (!huge)" replace "if (charged)"? See my reply to Mathew Wilcox. Cheers, Longman