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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 5D9F4C4360C for ; Wed, 16 Oct 2019 09:42:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2FF9A20872 for ; Wed, 16 Oct 2019 09:42:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728284AbfJPJmj (ORCPT ); Wed, 16 Oct 2019 05:42:39 -0400 Received: from mx2.suse.de ([195.135.220.15]:35158 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726689AbfJPJmj (ORCPT ); Wed, 16 Oct 2019 05:42:39 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 55EE6B284; Wed, 16 Oct 2019 09:42:38 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 879D61E3BDE; Wed, 16 Oct 2019 11:42:37 +0200 (CEST) Date: Wed, 16 Oct 2019 11:42:37 +0200 From: Jan Kara To: Eric Sandeen Cc: Jan Kara , Eric Sandeen , fsdevel , Al Viro Subject: Re: [PATCH V2] fs: avoid softlockups in s_inodes iterators Message-ID: <20191016094237.GE30337@quack2.suse.cz> References: <20191015073740.GA21550@quack2.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue 15-10-19 21:36:08, Eric Sandeen wrote: > On 10/15/19 2:37 AM, Jan Kara wrote: > > On Mon 14-10-19 16:30:24, Eric Sandeen wrote: > >> Anything that walks all inodes on sb->s_inodes list without rescheduling > >> risks softlockups. > >> > >> Previous efforts were made in 2 functions, see: > >> > >> c27d82f fs/drop_caches.c: avoid softlockups in drop_pagecache_sb() > >> ac05fbb inode: don't softlockup when evicting inodes > >> > >> but there hasn't been an audit of all walkers, so do that now. This > >> also consistently moves the cond_resched() calls to the bottom of each > >> loop in cases where it already exists. > >> > >> One loop remains: remove_dquot_ref(), because I'm not quite sure how > >> to deal with that one w/o taking the i_lock. > >> > >> Signed-off-by: Eric Sandeen > > > > Thanks Eric. The patch looks good to me. You can add: > > > > Reviewed-by: Jan Kara > > thanks > > > BTW, I suppose you need to add Al to pickup the patch? > > Yeah (cc'd now) > > But it was just pointed out to me that if/when the majority of inodes > at umount time have i_count == 0, we'll never hit the resched in > fsnotify_unmount_inodes() and may still have an issue ... Yeah, that's a good point. So that loop will need some further tweaking (like doing iget-iput dance in need_resched() case like in some other places). Honza -- Jan Kara SUSE Labs, CR