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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 1611AC282CE for ; Wed, 22 May 2019 19:21:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DC4A7217F9 for ; Wed, 22 May 2019 19:21:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558552880; bh=b3pnOJlavVTSMLrhfhWYxt52OURL4r336/7ktnNmvMU=; h=From:To:Cc:Subject:Date:List-ID:From; b=h837SBvswDrepWLfLIrlz68VVK21yLnqN1Qz6IJz7huiBVulOZYJSKMKWqvt5Tq4R ulagcAIMfLJpxpWhEPwVNIHvrRWr18d82kCxucS9TiyLsZbMbW0kCNNg05XtdvJ983 pHXA2hwj8W3jVk8sZcvf3Q9emFgw4r7PINYK7TtA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729805AbfEVTVT (ORCPT ); Wed, 22 May 2019 15:21:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:41666 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728615AbfEVTVS (ORCPT ); Wed, 22 May 2019 15:21:18 -0400 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 E0A2221473; Wed, 22 May 2019 19:21:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558552877; bh=b3pnOJlavVTSMLrhfhWYxt52OURL4r336/7ktnNmvMU=; h=From:To:Cc:Subject:Date:From; b=PlixEF4CxgQGNSweQt8/coqg8ojaOM9oB4bBFTRgfmqje53doDLyMIQ27dyp3glp0 I19MXb80ucwlK4uUyjrzDBnZpZ5X7qDt06hxxPrnNqDpf4x+bkcdvmD0/CUnidosLU ffFJhstru/frrjjE6a8peZ5LRt3uwSCOHThVt1yc= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Ross Lagerwall , Andreas Gruenbacher , Sasha Levin , cluster-devel@redhat.com Subject: [PATCH AUTOSEL 5.1 001/375] gfs2: Fix lru_count going negative Date: Wed, 22 May 2019 15:15:01 -0400 Message-Id: <20190522192115.22666-1-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ross Lagerwall [ Upstream commit 7881ef3f33bb80f459ea6020d1e021fc524a6348 ] Under certain conditions, lru_count may drop below zero resulting in a large amount of log spam like this: vmscan: shrink_slab: gfs2_dump_glock+0x3b0/0x630 [gfs2] \ negative objects to delete nr=-1 This happens as follows: 1) A glock is moved from lru_list to the dispose list and lru_count is decremented. 2) The dispose function calls cond_resched() and drops the lru lock. 3) Another thread takes the lru lock and tries to add the same glock to lru_list, checking if the glock is on an lru list. 4) It is on a list (actually the dispose list) and so it avoids incrementing lru_count. 5) The glock is moved to lru_list. 5) The original thread doesn't dispose it because it has been re-added to the lru list but the lru_count has still decreased by one. Fix by checking if the LRU flag is set on the glock rather than checking if the glock is on some list and rearrange the code so that the LRU flag is added/removed precisely when the glock is added/removed from lru_list. Signed-off-by: Ross Lagerwall Signed-off-by: Andreas Gruenbacher Signed-off-by: Sasha Levin --- fs/gfs2/glock.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index d32964cd11176..e4f6d39500bcc 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -183,15 +183,19 @@ static int demote_ok(const struct gfs2_glock *gl) void gfs2_glock_add_to_lru(struct gfs2_glock *gl) { + if (!(gl->gl_ops->go_flags & GLOF_LRU)) + return; + spin_lock(&lru_lock); - if (!list_empty(&gl->gl_lru)) - list_del_init(&gl->gl_lru); - else + list_del(&gl->gl_lru); + list_add_tail(&gl->gl_lru, &lru_list); + + if (!test_bit(GLF_LRU, &gl->gl_flags)) { + set_bit(GLF_LRU, &gl->gl_flags); atomic_inc(&lru_count); + } - list_add_tail(&gl->gl_lru, &lru_list); - set_bit(GLF_LRU, &gl->gl_flags); spin_unlock(&lru_lock); } @@ -201,7 +205,7 @@ static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl) return; spin_lock(&lru_lock); - if (!list_empty(&gl->gl_lru)) { + if (test_bit(GLF_LRU, &gl->gl_flags)) { list_del_init(&gl->gl_lru); atomic_dec(&lru_count); clear_bit(GLF_LRU, &gl->gl_flags); @@ -1159,8 +1163,7 @@ void gfs2_glock_dq(struct gfs2_holder *gh) !test_bit(GLF_DEMOTE, &gl->gl_flags)) fast_path = 1; } - if (!test_bit(GLF_LFLUSH, &gl->gl_flags) && demote_ok(gl) && - (glops->go_flags & GLOF_LRU)) + if (!test_bit(GLF_LFLUSH, &gl->gl_flags) && demote_ok(gl)) gfs2_glock_add_to_lru(gl); trace_gfs2_glock_queue(gh, 0); @@ -1456,6 +1459,7 @@ __acquires(&lru_lock) if (!spin_trylock(&gl->gl_lockref.lock)) { add_back_to_lru: list_add(&gl->gl_lru, &lru_list); + set_bit(GLF_LRU, &gl->gl_flags); atomic_inc(&lru_count); continue; } @@ -1463,7 +1467,6 @@ __acquires(&lru_lock) spin_unlock(&gl->gl_lockref.lock); goto add_back_to_lru; } - clear_bit(GLF_LRU, &gl->gl_flags); gl->gl_lockref.count++; if (demote_ok(gl)) handle_callback(gl, LM_ST_UNLOCKED, 0, false); @@ -1498,6 +1501,7 @@ static long gfs2_scan_glock_lru(int nr) if (!test_bit(GLF_LOCK, &gl->gl_flags)) { list_move(&gl->gl_lru, &dispose); atomic_dec(&lru_count); + clear_bit(GLF_LRU, &gl->gl_flags); freed++; continue; } -- 2.20.1