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=-11.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=no 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 2BF3DC4727F for ; Fri, 25 Sep 2020 17:22:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DE5F821D7A for ; Fri, 25 Sep 2020 17:22:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="PyvHoBQg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729415AbgIYRWn (ORCPT ); Fri, 25 Sep 2020 13:22:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52602 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727733AbgIYRWn (ORCPT ); Fri, 25 Sep 2020 13:22:43 -0400 Received: from mail-lf1-x136.google.com (mail-lf1-x136.google.com [IPv6:2a00:1450:4864:20::136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 12176C0613D3 for ; Fri, 25 Sep 2020 10:22:43 -0700 (PDT) Received: by mail-lf1-x136.google.com with SMTP id b12so3639289lfp.9 for ; Fri, 25 Sep 2020 10:22:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Ya/RZuQwonP8PPud7lCm2bOa/ougNTh1IMJmg7koWQI=; b=PyvHoBQgWuYhvQNjE7NE5hs89M+9kEHdGV2j/seaL5Gg0MlWI0M3tX0IFbaWMqXj1s ai1ySoBUH/pJJp9+Lt2njZA4fNnlVMdXvTFeaxT+0cvhcpS5izHZbaGSst5DxJjEc5+F ZNPMI630ovQTocKSg89ZIXTt+gZgkoXsInN7B4nwsREzwGBafMSTTG+JS9MTkAyGvpeJ mCTvE0+H1iacOG6BiB+OHTPMGuSJTKbL5nQyKWU76nXzqmqxP14mG4SPDaUIbo/sWOT3 kHrrT9YpdO3/IyFVoOp7L4bIBGWhB2qRiwq60yvM/lIcXa4y+Kzx96H4AT/v99RIvuPA QMfQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Ya/RZuQwonP8PPud7lCm2bOa/ougNTh1IMJmg7koWQI=; b=tfP/ZHxBNau3M464gKf5Omd7cwXhvbC1vdBDSFhNfNeYMCaePRcb9mV+/EqumFPjR4 TkI7qLRWxK8jMPzmITqABFQs39eUxCzQXDHr/L8GIhJ6sZNKD8cfxeDpTHysch43lSh3 V74ii18goO4XwbiG/17wKHeFDMG4vG9BvoEUW4Gm/DPOdPcpocRXIEkTU4kNlgu3piH+ zqi6NxA+nVP5zyRG8PUqOAzXP6WgOUe6RFd4P0D0y0FNL+2ADtLNitg0DTe1v5d7F7qD ont7iYNaJlKOhIVEgajkzaaSYrUPdDt6avHbupSxS+Q1iysmMcDVPo35DkFiKWWMMwTk U9iQ== X-Gm-Message-State: AOAM533mMzxXZCbLagepOp3jrKi1iDQADabMPBnIXM4Ak1iH9QgU19aB Y9YXF01WHngk+n3jsPqsCZaQhNSlJBmGTWUfRxGoHQ== X-Google-Smtp-Source: ABdhPJzcMlw0fOZLTa8UbxvxQ9K/MTDBtFoXm/rCC3pf0zAylKLPns8FI3+ijZEzImVWcIGbkPhF3RsHOU2PbQ6BiUI= X-Received: by 2002:a19:4084:: with SMTP id n126mr1581229lfa.54.1601054561128; Fri, 25 Sep 2020 10:22:41 -0700 (PDT) MIME-Version: 1.0 References: <20200915073303.GA754106@T590> <20200915224541.GB38283@mit.edu> <20200915230941.GA791425@T590> <20200916202026.GC38283@mit.edu> <20200917022051.GA1004828@T590> <20200917143012.GF38283@mit.edu> <20200924005901.GB1806978@T590> <20200924143345.GD482521@mit.edu> <20200925011311.GJ482521@mit.edu> <20200925073145.GC2388140@T590> <20200925161918.GD2388140@T590> In-Reply-To: From: Shakeel Butt Date: Fri, 25 Sep 2020 10:22:29 -0700 Message-ID: Subject: Re: REGRESSION: 37f4a24c2469: blk-mq: centralise related handling into blk_mq_get_driver_tag To: Linus Torvalds Cc: Ming Lei , "Theodore Y. Ts'o" , Jens Axboe , Ext4 Developers List , "linux-kernel@vger.kernel.org" , linux-block , Linux-MM , Roman Gushchin , Andrew Morton , Johannes Weiner , Vlastimil Babka Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 25, 2020 at 10:17 AM Linus Torvalds wrote: > > On Fri, Sep 25, 2020 at 9:19 AM Ming Lei wrote: > > > > git bisect shows the first bad commit: > > > > [10befea91b61c4e2c2d1df06a2e978d182fcf792] mm: memcg/slab: use a single set of > > kmem_caches for all allocations > > > > And I have double checked that the above commit is really the first bad > > commit for the list corruption issue of 'list_del corruption, ffffe1c241b00408->next > > is LIST_POISON1 (dead000000000100)', > > Thet commit doesn't revert cleanly, but I think that's purely because > we'd also need to revert > > 849504809f86 ("mm: memcg/slab: remove unused argument by charge_slab_page()") > 74d555bed5d0 ("mm: slab: rename (un)charge_slab_page() to > (un)account_slab_page()") > > too. > > Can you verify that a > > git revert 74d555bed5d0 849504809f86 10befea91b61 > > on top of current -git makes things work for you again? > > I'm going to do an rc8 this release simply because we have another VM > issue that I hope to get fixed - but there we know what the problem > and the fix _is_, it just needs some care. > > So if Roman (or somebody else) can see what's wrong and we can fix > this quickly, we don't need to go down the revert path, but .. > I think I have a theory. The issue is happening due to the potential infinite recursion: [ 5060.124412] ___cache_free+0x488/0x6b0 *****Second recursion [ 5060.128666] kfree+0xc9/0x1d0 [ 5060.131947] kmem_freepages+0xa0/0xf0 [ 5060.135746] slab_destroy+0x19/0x50 [ 5060.139577] slabs_destroy+0x6d/0x90 [ 5060.143379] ___cache_free+0x4a3/0x6b0 *****First recursion [ 5060.147896] kfree+0xc9/0x1d0 [ 5060.151082] kmem_freepages+0xa0/0xf0 [ 5060.155121] slab_destroy+0x19/0x50 [ 5060.159028] slabs_destroy+0x6d/0x90 [ 5060.162920] ___cache_free+0x4a3/0x6b0 [ 5060.167097] kfree+0xc9/0x1d0 ___cache_free() is calling cache_flusharray() to flush the local cpu array_cache if the cache has more elements than the limit (ac->avail >= ac->limit). cache_flusharray() is removing batchcount number of element from local cpu array_cache and pass it slabs_destroy (if the node shared cache is also full). Note that we have not updated local cpu array_cache size yet and called slabs_destroy() which can call kfree() through unaccount_slab_page(). We are on the same CPU and this recursive kfree again check the (ac->avail >= ac->limit) and call cache_flusharray() again and recurse indefinitely.