From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755215Ab2G3ReE (ORCPT ); Mon, 30 Jul 2012 13:34:04 -0400 Received: from mail-yx0-f174.google.com ([209.85.213.174]:44548 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755103Ab2G3Rd6 (ORCPT ); Mon, 30 Jul 2012 13:33:58 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg KH , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Konstantin Khlebnikov , Dave Chinner , Mel Gorman Subject: [ 41/41] vmscan: fix initial shrinker size handling Date: Mon, 30 Jul 2012 10:31:40 -0700 Message-Id: <20120730172904.512570228@linuxfoundation.org> X-Mailer: git-send-email 1.7.10.1.362.g242cab3 In-Reply-To: <20120730172901.306897424@linuxfoundation.org> References: <20120730172901.306897424@linuxfoundation.org> User-Agent: quilt/0.60-20.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Greg KH 3.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Konstantin Khlebnikov commit 635697c663f38106063d5659f0cf2e45afcd4bb5 upstream. Stable note: The commit [acf92b48: vmscan: shrinker->nr updates race and go wrong] aimed to reduce excessive reclaim of slab objects but had bug in how it treated shrinker functions that returned -1. A shrinker function can return -1, means that it cannot do anything without a risk of deadlock. For example prune_super() does this if it cannot grab a superblock refrence, even if nr_to_scan=0. Currently we interpret this -1 as a ULONG_MAX size shrinker and evaluate `total_scan' according to this. So the next time around this shrinker can cause really big pressure. Let's skip such shrinkers instead. Also make total_scan signed, otherwise the check (total_scan < 0) below never works. Signed-off-by: Konstantin Khlebnikov Cc: Dave Chinner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Mel Gorman Signed-off-by: Greg Kroah-Hartman --- mm/vmscan.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -248,12 +248,16 @@ unsigned long shrink_slab(struct shrink_ list_for_each_entry(shrinker, &shrinker_list, list) { unsigned long long delta; - unsigned long total_scan; - unsigned long max_pass; + long total_scan; + long max_pass; int shrink_ret = 0; long nr; long new_nr; + max_pass = do_shrinker_shrink(shrinker, shrink, 0); + if (max_pass <= 0) + continue; + /* * copy the current shrinker scan count into a local variable * and zero it so that other concurrent shrinker invocations @@ -264,7 +268,6 @@ unsigned long shrink_slab(struct shrink_ } while (cmpxchg(&shrinker->nr, nr, 0) != nr); total_scan = nr; - max_pass = do_shrinker_shrink(shrinker, shrink, 0); delta = (4 * nr_pages_scanned) / shrinker->seeks; delta *= max_pass; do_div(delta, lru_pages + 1);