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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 DFADDC0650F for ; Mon, 5 Aug 2019 13:24:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AFA5B20651 for ; Mon, 5 Aug 2019 13:24:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565011475; bh=D7qIjmi0nDi0uqZ+d6MM7cPHU1t96I4scwoAELhSSD0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=g1BLiJwYIZfhP4WdPXVdEZs/ePvkGhM6czl/WeJtur1U6stcgmWWX56kRTIxYR9kv MWwQydbsu6K0rKJMXQctUULt7oO+9lBDfHKoIeRtU2/fHJN+w0ePSd3KlTOeVCy11Q 6EhnNXy83CkmKlviyGBBN2Y8K6qLxpLH88WpgC9s= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729574AbfHENYe (ORCPT ); Mon, 5 Aug 2019 09:24:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:33026 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730590AbfHENYc (ORCPT ); Mon, 5 Aug 2019 09:24:32 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 7BB1C2087B; Mon, 5 Aug 2019 13:24:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565011471; bh=D7qIjmi0nDi0uqZ+d6MM7cPHU1t96I4scwoAELhSSD0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uK+0mXn1qspgbkkLBIQELtViAbhA33Na5LtHGzDYjClseuQK9WTqw0UH54H15eKeF Hes6s8k6ICvjJo69zjpJKJZGIZZCEUVttU1F9iR7EPs3xriIZEGAVbrvu0fRXvlfYs KxAED85jB0jtsRp2sWShgrqgwDxjNEehO+lzbtKE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Yang Shi , Shakeel Butt , Kirill Tkhai , Michal Hocko , Jan Hadrava , Vladimir Davydov , Johannes Weiner , Roman Gushchin , Hugh Dickins , Qian Cai , "Kirill A. Shutemov" , Andrew Morton , Linus Torvalds Subject: [PATCH 5.2 100/131] mm: vmscan: check if mem cgroup is disabled or not before calling memcg slab shrinker Date: Mon, 5 Aug 2019 15:03:07 +0200 Message-Id: <20190805124958.649680836@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190805124951.453337465@linuxfoundation.org> References: <20190805124951.453337465@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Archived-At: List-Archive: List-Post: From: Yang Shi commit fa1e512fac717f34e7c12d7a384c46e90a647392 upstream. Shakeel Butt reported premature oom on kernel with "cgroup_disable=memory" since mem_cgroup_is_root() returns false even though memcg is actually NULL. The drop_caches is also broken. It is because commit aeed1d325d42 ("mm/vmscan.c: generalize shrink_slab() calls in shrink_node()") removed the !memcg check before !mem_cgroup_is_root(). And, surprisingly root memcg is allocated even though memory cgroup is disabled by kernel boot parameter. Add mem_cgroup_disabled() check to make reclaimer work as expected. Link: http://lkml.kernel.org/r/1563385526-20805-1-git-send-email-yang.shi@linux.alibaba.com Fixes: aeed1d325d42 ("mm/vmscan.c: generalize shrink_slab() calls in shrink_node()") Signed-off-by: Yang Shi Reported-by: Shakeel Butt Reviewed-by: Shakeel Butt Reviewed-by: Kirill Tkhai Acked-by: Michal Hocko Cc: Jan Hadrava Cc: Vladimir Davydov Cc: Johannes Weiner Cc: Roman Gushchin Cc: Hugh Dickins Cc: Qian Cai Cc: Kirill A. Shutemov Cc: [4.19+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/vmscan.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -684,7 +684,14 @@ static unsigned long shrink_slab(gfp_t g unsigned long ret, freed = 0; struct shrinker *shrinker; - if (!mem_cgroup_is_root(memcg)) + /* + * The root memcg might be allocated even though memcg is disabled + * via "cgroup_disable=memory" boot parameter. This could make + * mem_cgroup_is_root() return false, then just run memcg slab + * shrink, but skip global shrink. This may result in premature + * oom. + */ + if (!mem_cgroup_disabled() && !mem_cgroup_is_root(memcg)) return shrink_slab_memcg(gfp_mask, nid, memcg, priority); if (!down_read_trylock(&shrinker_rwsem))