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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,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 5EB83C10F14 for ; Tue, 15 Oct 2019 07:37:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 30F7121848 for ; Tue, 15 Oct 2019 07:37:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726880AbfJOHhp (ORCPT ); Tue, 15 Oct 2019 03:37:45 -0400 Received: from mx2.suse.de ([195.135.220.15]:41112 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725890AbfJOHhp (ORCPT ); Tue, 15 Oct 2019 03:37:45 -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 DA59DB588; Tue, 15 Oct 2019 07:37:41 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 5E9A41E4A8A; Tue, 15 Oct 2019 09:37:40 +0200 (CEST) Date: Tue, 15 Oct 2019 09:37:40 +0200 From: Jan Kara To: Eric Sandeen Cc: fsdevel Subject: Re: [PATCH V2] fs: avoid softlockups in s_inodes iterators Message-ID: <20191015073740.GA21550@quack2.suse.cz> References: 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 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 BTW, I suppose you need to add Al to pickup the patch? Honza > --- > > V2: Drop unrelated iput cleanups in fsnotify > > diff --git a/fs/drop_caches.c b/fs/drop_caches.c > index d31b6c72b476..dc1a1d5d825b 100644 > --- a/fs/drop_caches.c > +++ b/fs/drop_caches.c > @@ -35,11 +35,11 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused) > spin_unlock(&inode->i_lock); > spin_unlock(&sb->s_inode_list_lock); > - cond_resched(); > invalidate_mapping_pages(inode->i_mapping, 0, -1); > iput(toput_inode); > toput_inode = inode; > + cond_resched(); > spin_lock(&sb->s_inode_list_lock); > } > spin_unlock(&sb->s_inode_list_lock); > diff --git a/fs/inode.c b/fs/inode.c > index fef457a42882..b0c789bb3dba 100644 > --- a/fs/inode.c > +++ b/fs/inode.c > @@ -676,6 +676,7 @@ int invalidate_inodes(struct super_block *sb, bool kill_dirty) > struct inode *inode, *next; > LIST_HEAD(dispose); > +again: > spin_lock(&sb->s_inode_list_lock); > list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) { > spin_lock(&inode->i_lock); > @@ -698,6 +699,13 @@ int invalidate_inodes(struct super_block *sb, bool kill_dirty) > inode_lru_list_del(inode); > spin_unlock(&inode->i_lock); > list_add(&inode->i_lru, &dispose); > + > + if (need_resched()) { > + spin_unlock(&sb->s_inode_list_lock); > + cond_resched(); > + dispose_list(&dispose); > + goto again; > + } > } > spin_unlock(&sb->s_inode_list_lock); > diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c > index 2ecef6155fc0..ac9eb273e28c 100644 > --- a/fs/notify/fsnotify.c > +++ b/fs/notify/fsnotify.c > @@ -77,6 +77,7 @@ static void fsnotify_unmount_inodes(struct super_block *sb) > iput_inode = inode; > + cond_resched(); > spin_lock(&sb->s_inode_list_lock); > } > spin_unlock(&sb->s_inode_list_lock); > diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c > index 6e826b454082..4a085b3c7cac 100644 > --- a/fs/quota/dquot.c > +++ b/fs/quota/dquot.c > @@ -985,6 +985,7 @@ static int add_dquot_ref(struct super_block *sb, int type) > * later. > */ > old_inode = inode; > + cond_resched(); > spin_lock(&sb->s_inode_list_lock); > } > spin_unlock(&sb->s_inode_list_lock); > -- Jan Kara SUSE Labs, CR