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,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 D84D7C282DC for ; Wed, 22 May 2019 19:30:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AA92C20879 for ; Wed, 22 May 2019 19:30:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558553429; bh=TSxv4XIeGGv8euTEvyL7iVFJBgCZzL+AxbODGUtTQsI=; h=From:To:Cc:Subject:Date:List-ID:From; b=BHW8uqVd39GDpVtsRA+ENuetSAN30TazZh4DWzqwbAZB1wlcmoIZ+p5GWYFMsnzxJ FB2s9bQuD+PQV5k87xtwtxAhpLcOmAe0qWMxF23gad8Ea7ZCPXBVgVg8pTwcoQy/+A xtxp/2B3tO9uSoT3pAYha8mH6092vXvXwCjg3PDI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733253AbfEVTa2 (ORCPT ); Wed, 22 May 2019 15:30:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:53778 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732339AbfEVTaT (ORCPT ); Wed, 22 May 2019 15:30:19 -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 6D57E217F9; Wed, 22 May 2019 19:30:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558553419; bh=TSxv4XIeGGv8euTEvyL7iVFJBgCZzL+AxbODGUtTQsI=; h=From:To:Cc:Subject:Date:From; b=1LT5d0D4lc5AHLKO/7VdHSLRqUWHtrdF98UmGkXsDsm0VMxfIY9gil5es6kvB+s15 PcIVmluJoDZt1NuD6Sx7Xfm4V2Vo7R9+U/Ub6yFENgkP/9OE/J4tVJKqYjfxr+kLkg L6tw0aHnUCxLBvAv+pSq57DDPSHsenMeZEMJl7tQ= 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 4.9 001/114] gfs2: Fix lru_count going negative Date: Wed, 22 May 2019 15:28:24 -0400 Message-Id: <20190522193017.26567-1-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 7a8b1d72e3d91..efd44d5645d83 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -136,22 +136,26 @@ 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); } static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl) { 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); @@ -1048,8 +1052,7 @@ 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); @@ -1349,6 +1352,7 @@ __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; } @@ -1356,7 +1360,6 @@ __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); @@ -1392,6 +1395,7 @@ 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