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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,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 E638CC432C0 for ; Wed, 27 Nov 2019 21:23:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BA1AD21556 for ; Wed, 27 Nov 2019 21:23:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574889783; bh=v2Lr6UhqiPVvG1GHncj3T4v9MmrlPcSOl5zQ1vp0id0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=UTIPCSeM9kuJpFahReQJsRQIrqld+6XlBLfnt38T9OwQXys1BiZBfQI3xbl8ofsh+ TrfL0fzlwSWZspmTRlIf/bL3D2dWM8Q3rnSXqzn9oQ/3RthCwTsI5JXlKzGUjx0gPc dt3x804iuvKxOthrWnkDHPEz8jBWljIS6YC4a7dc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732274AbfK0VXA (ORCPT ); Wed, 27 Nov 2019 16:23:00 -0500 Received: from mail.kernel.org ([198.145.29.99]:58742 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727468AbfK0VFH (ORCPT ); Wed, 27 Nov 2019 16:05:07 -0500 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 5BAAB215F1; Wed, 27 Nov 2019 21:05:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574888707; bh=v2Lr6UhqiPVvG1GHncj3T4v9MmrlPcSOl5zQ1vp0id0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dDRHbfyXr9z26QK/JcM5flg7ze0J6WqwTqnxdw4jxHSAsaOjH1ekHHb66wPPiojGD H19t+ytahxYX52b1A5n9eaqhAZWIuD4wW17IatWiJOXCvnTz+HLZ1JvygujE0PP/df 2+T6czjFYA+KllBaIeAkfnv6y2+0vFjrA1BFaE0E= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Roman Gushchin , Mike Galbraith , Rik van Riel , Michal Hocko , Johannes Weiner , Vladimir Davydov , Shakeel Butt , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH 4.19 195/306] mm: handle no memcg case in memcg_kmem_charge() properly Date: Wed, 27 Nov 2019 21:30:45 +0100 Message-Id: <20191127203129.442793037@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191127203114.766709977@linuxfoundation.org> References: <20191127203114.766709977@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 From: Roman Gushchin [ Upstream commit e68599a3c3ad0f3171a7cb4e48aa6f9a69381902 ] Mike Galbraith reported a regression caused by the commit 9b6f7e163cd0 ("mm: rework memcg kernel stack accounting") on a system with "cgroup_disable=memory" boot option: the system panics with the following stack trace: BUG: unable to handle kernel NULL pointer dereference at 00000000000000f8 PGD 0 P4D 0 Oops: 0002 [#1] PREEMPT SMP PTI CPU: 0 PID: 1 Comm: systemd Not tainted 4.19.0-preempt+ #410 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20180531_142017-buildhw-08.phx2.fed4 RIP: 0010:page_counter_try_charge+0x22/0xc0 Code: 41 5d c3 c3 0f 1f 40 00 0f 1f 44 00 00 48 85 ff 0f 84 a7 00 00 00 41 56 48 89 f8 49 89 fe 49 Call Trace: try_charge+0xcb/0x780 memcg_kmem_charge_memcg+0x28/0x80 memcg_kmem_charge+0x8b/0x1d0 copy_process.part.41+0x1ca/0x2070 _do_fork+0xd7/0x3d0 do_syscall_64+0x5a/0x180 entry_SYSCALL_64_after_hwframe+0x49/0xbe The problem occurs because get_mem_cgroup_from_current() returns the NULL pointer if memory controller is disabled. Let's check if this is a case at the beginning of memcg_kmem_charge() and just return 0 if mem_cgroup_disabled() returns true. This is how we handle this case in many other places in the memory controller code. Link: http://lkml.kernel.org/r/20181029215123.17830-1-guro@fb.com Fixes: 9b6f7e163cd0 ("mm: rework memcg kernel stack accounting") Signed-off-by: Roman Gushchin Reported-by: Mike Galbraith Acked-by: Rik van Riel Acked-by: Michal Hocko Cc: Johannes Weiner Cc: Vladimir Davydov Cc: Shakeel Butt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- mm/memcontrol.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 5af38d8a9afd3..3a3d109dce215 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2678,7 +2678,7 @@ int memcg_kmem_charge(struct page *page, gfp_t gfp, int order) struct mem_cgroup *memcg; int ret = 0; - if (memcg_kmem_bypass()) + if (mem_cgroup_disabled() || memcg_kmem_bypass()) return 0; memcg = get_mem_cgroup_from_current(); -- 2.20.1