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=-3.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 EEFBDC3F2C6 for ; Tue, 3 Mar 2020 19:42:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8955F208C3 for ; Tue, 3 Mar 2020 19:42:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="M31Zomw/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8955F208C3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id F24DE6B0005; Tue, 3 Mar 2020 14:42:50 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id ED5D06B0006; Tue, 3 Mar 2020 14:42:50 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D9D966B0007; Tue, 3 Mar 2020 14:42:50 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0084.hostedemail.com [216.40.44.84]) by kanga.kvack.org (Postfix) with ESMTP id BF3336B0005 for ; Tue, 3 Mar 2020 14:42:50 -0500 (EST) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 37795181AC9CC for ; Tue, 3 Mar 2020 19:42:50 +0000 (UTC) X-FDA: 76555073700.10.base61_52ec169c9be2c X-HE-Tag: base61_52ec169c9be2c X-Filterd-Recvd-Size: 5795 Received: from mail-ed1-f66.google.com (mail-ed1-f66.google.com [209.85.208.66]) by imf46.hostedemail.com (Postfix) with ESMTP for ; Tue, 3 Mar 2020 19:42:49 +0000 (UTC) Received: by mail-ed1-f66.google.com with SMTP id c62so6035280edf.0 for ; Tue, 03 Mar 2020 11:42:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=JAnrXNoKVdk8Uvr5YEvtC60qsUiezqAJKWOyNxMVPoI=; b=M31Zomw/Z4J17XwvPETFO6IQPysi6c8IP042ZxRZiIpojXXLGH+VlrkuIzoXjX1eJ1 PbuEYLhSQe91wMO1OktYQRiZpIcNSsaJdhcuCrwoY5UnAwiqoKsQxLqdjBOR1Z97LS4g qKG73CTwykggZPBi6i9MSBTeZdBExk7oEtv3CI6wSQOsyOCre6qng2LLBANgew9s7Lkq SgIN1DKYxBnFULfVcqe5Hn88aqBaqrji9S8YeDRhcjRTHRmON8FFZWGo/pGjhIJt6ek6 KCJ3RfG0WE5BW9JQscTF5v6K/F/01FtKVRafDWF9rrOMqApDi3hU/E2k7HdPiyt1u80s Anyg== 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=JAnrXNoKVdk8Uvr5YEvtC60qsUiezqAJKWOyNxMVPoI=; b=k6M7B1UKidQ16rxOzYY535vD8laDdAWxhnlp4xuIxo7jW/bPQPfJK1Jr38sKb0ytPz 2bmU2tOjRAGCZfFSpRUL2+Lg9Q0jJhHuoEGNhZ+WkF7JNtuz57ZaVh2YDtIeQVBRzZeh xrtQn9vCIy8R3P1NVquRbwtIFQh0OvPAbwxwK3daGiBi8OBrfUWAxemIJ1R6/BtKYUuu ETWT2P2YoPyBAyM+rK4gTJnbgf3Gn+tABlJKwu3tww89s+EiQZHilQU2KG3cFVmMA+Ef FMJRYPABEeMJHED3bAcfNjjpeJ2RzLWMYK8voemJs7sOi+AHWx6i7U/7ZMoMrJeDvEEh lvyQ== X-Gm-Message-State: ANhLgQ2TG9gy1bx1tLhQt2wZlZCTOuFYXupkbJZvv/sl24ETdAMfph4f 9GlSPtU9v3/DYLc5ctEYXqYMD+mpIqJLgcGbJTE= X-Google-Smtp-Source: ADFU+vv9pNPmE3J8o/HIQVw/MBBXYBLfMq+I1ubvAMKm9Cj752jLznHGROOc8XgeHxryyPCzG0hDqoxuOp+YgGg4B9Y= X-Received: by 2002:a50:81e6:: with SMTP id 93mr5829172ede.343.1583264568764; Tue, 03 Mar 2020 11:42:48 -0800 (PST) MIME-Version: 1.0 References: <0a37bb7d-18a7-c43c-52a5-f13a34decf69@i-love.sakura.ne.jp> In-Reply-To: From: Yang Shi Date: Tue, 3 Mar 2020 11:42:31 -0800 Message-ID: Subject: Re: fs/buffer.c: WARNING: alloc_page_buffers while mke2fs To: Shakeel Butt Cc: Tetsuo Handa , Naresh Kamboju , linux-mm , Andrew Morton , Mel Gorman , Michal Hocko , Dan Schatzberg , Johannes Weiner Content-Type: text/plain; charset="UTF-8" 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: On Tue, Mar 3, 2020 at 10:15 AM Shakeel Butt wrote: > > On Tue, Mar 3, 2020 at 9:47 AM Yang Shi wrote: > > > > On Tue, Mar 3, 2020 at 2:53 AM Tetsuo Handa > > wrote: > > > > > > Hello, Naresh. > > > > > > > [ 98.003346] WARNING: CPU: 2 PID: 340 at > > > > include/linux/sched/mm.h:323 alloc_page_buffers+0x210/0x288 > > > > > > This is > > > > > > /** > > > * memalloc_use_memcg - Starts the remote memcg charging scope. > > > * @memcg: memcg to charge. > > > * > > > * This function marks the beginning of the remote memcg charging scope. All the > > > * __GFP_ACCOUNT allocations till the end of the scope will be charged to the > > > * given memcg. > > > * > > > * NOTE: This function is not nesting safe. > > > */ > > > static inline void memalloc_use_memcg(struct mem_cgroup *memcg) > > > { > > > WARN_ON_ONCE(current->active_memcg); > > > current->active_memcg = memcg; > > > } > > > > > > which is about memcg. Redirecting to linux-mm. > > > > Isn't this triggered by ("loop: use worker per cgroup instead of > > kworker") in linux-next, which converted loop driver to use worker per > > cgroup, so it may have multiple workers work at the mean time? > > > > So they may share the same "current", then it may cause kind of nested > > call to memalloc_use_memcg(). > > > > Could you please try the below debug patch? This is not the proper > > fix, but it may help us narrow down the problem. > > > > diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h > > index c49257a..1cc1cdc 100644 > > --- a/include/linux/sched/mm.h > > +++ b/include/linux/sched/mm.h > > @@ -320,6 +320,10 @@ static inline void > > memalloc_nocma_restore(unsigned int flags) > > */ > > static inline void memalloc_use_memcg(struct mem_cgroup *memcg) > > { > > + if ((current->flags & PF_KTHREAD) && > > + current->active_memcg) > > + return; > > + > > WARN_ON_ONCE(current->active_memcg); > > current->active_memcg = memcg; > > } > > > > Maybe it's time to make memalloc_use_memcg() nesting safe. Need handle the below case: CPU A CPU B memalloc_use_memcg memalloc_use_memcg memalloc_unuse_memcg memalloc_unuse_memcg They may manipulate the same task->active_memcg, so CPU B may still see wrong memcg, and the last call to memalloc_unuse_memcg() on CPU B may not restore active_memcg to NULL. And, some code depends on correct active_memcg.