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=-9.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED,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 9982DC072B1 for ; Thu, 30 May 2019 03:47:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6EF39248C7 for ; Thu, 30 May 2019 03:47:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559188057; bh=WksFeKBKm23ZOKJUdAGeHa17sDokfaDq+8RAvwQ/XTw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ty/2kxGKsILlp9M5XtANhgKpugsSFovI0lBPcHPgSn/9hQoPIGb6wWALwV5ar6Fwu UpQUApFeOpD0hUJ7PCZWOtbTFTQ7nsICV9QwWxNJX5USbYUEL+bSremxbZMKWIJyM4 WycNcgd7BiR8nLP3CUcsdEum68ZS3N4DPeR1TmeU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731703AbfE3Drc (ORCPT ); Wed, 29 May 2019 23:47:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:58924 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732217AbfE3DUc (ORCPT ); Wed, 29 May 2019 23:20:32 -0400 Received: from localhost (ip67-88-213-2.z213-88-67.customer.algx.net [67.88.213.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D6A0E2492F; Thu, 30 May 2019 03:20:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559186431; bh=WksFeKBKm23ZOKJUdAGeHa17sDokfaDq+8RAvwQ/XTw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eSqEyP28PsTMsUpatIThmXy0Tcn5BVmEmwIaoeysDWedNt6jQtGBSZ8qd6wnUEUh5 aGvgp5WuKAFJOe7k67li64Ut+APX5p8AztBwhiLRcZy40q6PF3mHUP9xDtTKag4MCH ZVaCkUH9oyGZCLAAtJUZ4zvb31WSNnSo/kM8YFc4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ross Lagerwall , Andreas Gruenbacher , Sasha Levin Subject: [PATCH 4.9 023/128] gfs2: Fix lru_count going negative Date: Wed, 29 May 2019 20:05:55 -0700 Message-Id: <20190530030438.979746132@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190530030432.977908967@linuxfoundation.org> References: <20190530030432.977908967@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org [ 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