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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12F85C433FE for ; Thu, 14 Oct 2021 12:08:05 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id AB45F60174 for ; Thu, 14 Oct 2021 12:08:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org AB45F60174 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 1A5DB900002; Thu, 14 Oct 2021 08:08:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1564C6B0071; Thu, 14 Oct 2021 08:08:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 01DF8900002; Thu, 14 Oct 2021 08:08:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0217.hostedemail.com [216.40.44.217]) by kanga.kvack.org (Postfix) with ESMTP id E312E6B006C for ; Thu, 14 Oct 2021 08:08:03 -0400 (EDT) Received: from smtpin33.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 95D112D228 for ; Thu, 14 Oct 2021 12:08:03 +0000 (UTC) X-FDA: 78694919646.33.3A115CA Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf01.hostedemail.com (Postfix) with ESMTP id 63542507FFF5 for ; Thu, 14 Oct 2021 12:08:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=hH5UMRaxYgGEu1UnuovaeWTRlAQ8d4MJU3Qaco30nXM=; b=STj+i2I0I9isIXfM1cHJyzkxjS 1WGpZX411ETrIv8coMsdeRJOdqFKgfL7uWXTdSiXULdQf3apLFdGGLwy5KdUJSoUHR51sFH6+2ykj rXsF8CmBC7qZ0vhMr3gdBgQJK+irQEqinfbKRMIWv/Ytde4c8k/MYiJO+J9Ar/m9mTidvMxHUG5on 1CbJz+vbeaWXWE8FBeCeYcTokrOfXokX8bpW3wzXwZ+UT0TJ9KzFdLvHlMYgm6KeaZO0wY8wQqdMR xmF73fgKlprTDqWoKInPPZTRQFF1v/YryTqHrXzt5Oy00Vt7tsmGVz/KqUPjLOqc55V4TvLg05bG6 ZTvxxtUA==; Received: from hch by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mazUp-008JXb-NB; Thu, 14 Oct 2021 12:06:35 +0000 Date: Thu, 14 Oct 2021 13:06:03 +0100 From: Christoph Hellwig To: Zqiang Cc: akpm@linux-foundation.org, sunhao.th@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] mm: backing-dev: use kfree_rcu() instead of synchronize_rcu_expedited() Message-ID: References: <20211014082433.30733-1-qiang.zhang1211@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211014082433.30733-1-qiang.zhang1211@gmail.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 63542507FFF5 X-Stat-Signature: d95dnmf8xn5w5cj5row8tpi5fpy4qqro Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=STj+i2I0; dmarc=none; spf=none (imf01.hostedemail.com: domain of BATV+26e5a4942f97f8596db9+6626+infradead.org+hch@casper.srs.infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=BATV+26e5a4942f97f8596db9+6626+infradead.org+hch@casper.srs.infradead.org X-HE-Tag: 1634213281-441132 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 Thu, Oct 14, 2021 at 04:24:33PM +0800, Zqiang wrote: > > __init_work+0x2d/0x50 > synchronize_rcu_expedited+0x3af/0x650 > bdi_remove_from_list [inline] > bdi_unregister+0x17f/0x5c0 > release_bdi+0xa1/0xc0 > kref_put [inline] > bdi_put+0x72/0xa0 > bdev_free_inode+0x11e/0x220 > i_callback+0x3f/0x70 > rcu_do_batch [inline] > rcu_core+0x76d/0x16c0 > __do_softirq+0x1d7/0x93b > invoke_softirq [inline] > __irq_exit_rcu [inline] > irq_exit_rcu+0xf2/0x130 > sysvec_apic_timer_interrupt+0x93/0xc0 > > The bdi_remove_from_list() is called in RCU softirq, however the > synchronize_rcu_expedited() will produce sleep action, use kfree_rcu() > instead of it. What workload is this running? If we hit the RCU unregister path from inode freeing we have a lifetime problem somewhere that we need to fix first.