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=DKIM_INVALID,DKIM_SIGNED, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 3F667C43141 for ; Sat, 16 Nov 2019 15:46:11 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0478320836 for ; Sat, 16 Nov 2019 15:46:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="GKnIuVN5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0478320836 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id AA7826B026D; Sat, 16 Nov 2019 10:46:10 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A57D26B026E; Sat, 16 Nov 2019 10:46:10 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 96DD66B026F; Sat, 16 Nov 2019 10:46:10 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0233.hostedemail.com [216.40.44.233]) by kanga.kvack.org (Postfix) with ESMTP id 818926B026D for ; Sat, 16 Nov 2019 10:46:10 -0500 (EST) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id 39D23611D for ; Sat, 16 Nov 2019 15:46:10 +0000 (UTC) X-FDA: 76162566900.28.crib35_18b4ec117895b X-HE-Tag: crib35_18b4ec117895b X-Filterd-Recvd-Size: 4277 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf16.hostedemail.com (Postfix) with ESMTP for ; Sat, 16 Nov 2019 15:46:09 +0000 (UTC) Received: from sasha-vm.mshome.net (unknown [50.234.116.4]) (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 275CF2086A; Sat, 16 Nov 2019 15:46:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573919168; bh=iLeu/7+A59mHww5wMPQ7+f/gfyrQdTMOJFAQRguBkd0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GKnIuVN5+bvLWzD2MSCnXJpfOgeMH2FO6qQ/ZfW2zvmu3H1sq+c+0QyPugSJqgyVw jOKcDOhWex0NbNfBv09PpiR1ESQHMY+a7qJHxpdhxkTDz4El9yKomOyS4FPPb5K+w8 jy5FZvTOFDGZaCbNo/MfySuLuC0KcNlHhLVQ5oyQ= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Roman Gushchin , Mike Galbraith , Rik van Riel , Michal Hocko , Johannes Weiner , Vladimir Davydov , Shakeel Butt , Andrew Morton , Linus Torvalds , Sasha Levin , cgroups@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH AUTOSEL 4.19 178/237] mm: handle no memcg case in memcg_kmem_charge() properly Date: Sat, 16 Nov 2019 10:40:13 -0500 Message-Id: <20191116154113.7417-178-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191116154113.7417-1-sashal@kernel.org> References: <20191116154113.7417-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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=3Dmemory" boot option: the system panics with the followi= ng stack trace: BUG: unable to handle kernel NULL pointer dereference at 00000000000000= f8 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 e0f7b94a4e9bc..b3220d2102461 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 =3D 0; =20 - if (memcg_kmem_bypass()) + if (mem_cgroup_disabled() || memcg_kmem_bypass()) return 0; =20 memcg =3D get_mem_cgroup_from_current(); --=20 2.20.1