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=-9.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 6D6E1C43381 for ; Sat, 23 Feb 2019 21:15:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 31D5120651 for ; Sat, 23 Feb 2019 21:15:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550956554; bh=ZQYzZvmYleW+xDwpweidtAETk2kj9F9L3xPKu/RQjcg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=e3votbPP+QYc80AaGIScPWVnnCeERbr6Ppic+qhSRAf8GpCJ7vQBmHKuD9nT8/Vjb ETWizLYrZkp/dNSZJrfO4YySH/rYf72uogiT9RrOugpxbw/ahEuiOXKGhY98zHyFpM fVfuyTUhE2XelBnzzY8ybSeoTN5BJiwKPY95NwiY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729808AbfBWVKo (ORCPT ); Sat, 23 Feb 2019 16:10:44 -0500 Received: from mail.kernel.org ([198.145.29.99]:46916 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728570AbfBWVKn (ORCPT ); Sat, 23 Feb 2019 16:10:43 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D2EB32085A; Sat, 23 Feb 2019 21:10:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550956242; bh=ZQYzZvmYleW+xDwpweidtAETk2kj9F9L3xPKu/RQjcg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GwtTbUieyY8oDVu0G4w8PO9ZNdNiuUCt6eWVQ+pHaM9RPMV4F3WRW6AHrjxHCVfEM 4Rc6POoj0u5QXOIwixoPXhrSU5K3p+kmh00p3hE9QnqU0gqcnGwB1j9im3zKHcZEmK qYc2R4+O59oJXP80nTn2Au40xfmwSAkVGHLgCk1A= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Jan Kara , Al Viro , Andrew Morton , Linus Torvalds , Sasha Levin , linux-fsdevel@vger.kernel.org Subject: [PATCH AUTOSEL 4.9 30/32] fs/drop_caches.c: avoid softlockups in drop_pagecache_sb() Date: Sat, 23 Feb 2019 16:09:49 -0500 Message-Id: <20190223210951.202268-30-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190223210951.202268-1-sashal@kernel.org> References: <20190223210951.202268-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Jan Kara [ Upstream commit c27d82f52f75fc9d8d9d40d120d2a96fdeeada5e ] When superblock has lots of inodes without any pagecache (like is the case for /proc), drop_pagecache_sb() will iterate through all of them without dropping sb->s_inode_list_lock which can lead to softlockups (one of our customers hit this). Fix the problem by going to the slow path and doing cond_resched() in case the process needs rescheduling. Link: http://lkml.kernel.org/r/20190114085343.15011-1-jack@suse.cz Signed-off-by: Jan Kara Acked-by: Michal Hocko Reviewed-by: Andrew Morton Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- fs/drop_caches.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/drop_caches.c b/fs/drop_caches.c index d72d52b904333..280460fef0664 100644 --- a/fs/drop_caches.c +++ b/fs/drop_caches.c @@ -20,8 +20,13 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused) spin_lock(&sb->s_inode_list_lock); list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { spin_lock(&inode->i_lock); + /* + * We must skip inodes in unusual state. We may also skip + * inodes without pages but we deliberately won't in case + * we need to reschedule to avoid softlockups. + */ if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) || - (inode->i_mapping->nrpages == 0)) { + (inode->i_mapping->nrpages == 0 && !need_resched())) { spin_unlock(&inode->i_lock); continue; } @@ -29,6 +34,7 @@ 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; -- 2.19.1