From patchwork Tue Nov 3 18:16:55 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 1393282 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.linux.it (client-ip=2001:1418:10:5::2; helo=picard.linux.it; envelope-from=ltp-bounces+incoming=patchwork.ozlabs.org@lists.linux.it; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=default header.b=Uc7mmefN; dkim-atps=neutral Received: from picard.linux.it (unknown [IPv6:2001:1418:10:5::2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4CQdL04GPfz9sVM for ; Wed, 4 Nov 2020 05:17:15 +1100 (AEDT) Received: from picard.linux.it (localhost [IPv6:::1]) by picard.linux.it (Postfix) with ESMTP id 48A133C546F for ; Tue, 3 Nov 2020 19:17:02 +0100 (CET) X-Original-To: ltp@lists.linux.it Delivered-To: ltp@picard.linux.it Received: from in-2.smtp.seeweb.it (in-2.smtp.seeweb.it [217.194.8.2]) by picard.linux.it (Postfix) with ESMTP id 03A353C3019 for ; Tue, 3 Nov 2020 19:16:59 +0100 (CET) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by in-2.smtp.seeweb.it (Postfix) with ESMTPS id C5F7A601231 for ; Tue, 3 Nov 2020 19:16:58 +0100 (CET) Received: from localhost.localdomain (c-71-198-47-131.hsd1.ca.comcast.net [71.198.47.131]) (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 9DA7A207BB; Tue, 3 Nov 2020 18:16:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604427415; bh=YWXD/g1RdgBXEoQrbh+xr1Ib84t3pHEoj4KNTOEYIHM=; h=Date:From:To:Subject:From; b=Uc7mmefN76aO+mtLUqP3d22TffA+Z91EDE5HebjK9qKAKFXlhmOfvNJEKvPprqz6j E5aMrDTiqaajpWnee3Jk6zLlCimTCpPryaoqhmq9vJAz4sU+pkDNfJLkEresnTQp1H WjwCGArgXGpWDFGP4DiaMf5n/VyQLbz22jKJCRss= Date: Tue, 03 Nov 2020 10:16:55 -0800 From: akpm@linux-foundation.org To: guro@fb.com, hannes@cmpxchg.org, ltp@lists.linux.it, mhocko@kernel.org, mkoutny@suse.com, mm-commits@vger.kernel.org, rpalethorpe@suse.com, shakeelb@google.com, stable@vger.kernel.org Message-ID: <20201103181655.kLttb0Xdl%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 MIME-Version: 1.0 X-Virus-Scanned: clamav-milter 0.102.4 at in-2.smtp.seeweb.it X-Virus-Status: Clean X-Spam-Status: No, score=2.6 required=7.0 tests=DKIM_SIGNED,DKIM_VALID, SORTED_RECIPS,SPF_HELO_NONE,SPF_PASS autolearn=disabled version=3.4.4 X-Spam-Level: ** X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on in-2.smtp.seeweb.it Subject: [LTP] [merged] mm-memcg-link-page-counters-to-root-if-use_hierarchy-is-false.patch removed from -mm tree X-BeenThere: ltp@lists.linux.it X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux Test Project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: ltp-bounces+incoming=patchwork.ozlabs.org@lists.linux.it Sender: "ltp" The patch titled Subject: mm: memcg: link page counters to root if use_hierarchy is false has been removed from the -mm tree. Its filename was mm-memcg-link-page-counters-to-root-if-use_hierarchy-is-false.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Roman Gushchin Subject: mm: memcg: link page counters to root if use_hierarchy is false Richard reported a warning which can be reproduced by running the LTP madvise6 test (cgroup v1 in the non-hierarchical mode should be used): [ 9.841552] ------------[ cut here ]------------ [ 9.841788] WARNING: CPU: 0 PID: 12 at mm/page_counter.c:57 page_counter_uncharge (mm/page_counter.c:57 mm/page_counter.c:50 mm/page_counter.c:156) [ 9.841982] Modules linked in: [ 9.842072] CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.9.0-rc7-22-default #77 [ 9.842266] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-48-gd9c812d-rebuilt.opensuse.org 04/01/2014 [ 9.842571] Workqueue: events drain_local_stock [ 9.842750] RIP: 0010:page_counter_uncharge (mm/page_counter.c:57 mm/page_counter.c:50 mm/page_counter.c:156) [ 9.842894] Code: 0f c1 45 00 4c 29 e0 48 89 ef 48 89 c3 48 89 c6 e8 2a fe ff ff 48 85 db 78 10 48 8b 6d 28 48 85 ed 75 d8 5b 5d 41 5c 41 5d c3 <0f> 0b eb ec 90 e8 4b f9 88 2a 48 8b 17 48 39 d6 72 41 41 54 49 89 [ 9.843438] RSP: 0018:ffffb1c18006be28 EFLAGS: 00010086 [ 9.843585] RAX: ffffffffffffffff RBX: ffffffffffffffff RCX: ffff94803bc2cae0 [ 9.843806] RDX: 0000000000000001 RSI: ffffffffffffffff RDI: ffff948007d2b248 [ 9.844026] RBP: ffff948007d2b248 R08: ffff948007c58eb0 R09: ffff948007da05ac [ 9.844248] R10: 0000000000000018 R11: 0000000000000018 R12: 0000000000000001 [ 9.844477] R13: ffffffffffffffff R14: 0000000000000000 R15: ffff94803bc2cac0 [ 9.844696] FS: 0000000000000000(0000) GS:ffff94803bc00000(0000) knlGS:0000000000000000 [ 9.844915] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 9.845096] CR2: 00007f0579ee0384 CR3: 000000002cc0a000 CR4: 00000000000006f0 [ 9.845319] Call Trace: [ 9.845429] __memcg_kmem_uncharge (mm/memcontrol.c:3022) [ 9.845582] drain_obj_stock (./include/linux/rcupdate.h:689 mm/memcontrol.c:3114) [ 9.845684] drain_local_stock (mm/memcontrol.c:2255) [ 9.845789] process_one_work (./arch/x86/include/asm/jump_label.h:25 ./include/linux/jump_label.h:200 ./include/trace/events/workqueue.h:108 kernel/workqueue.c:2274) [ 9.845898] worker_thread (./include/linux/list.h:282 kernel/workqueue.c:2416) [ 9.846034] ? process_one_work (kernel/workqueue.c:2358) [ 9.846162] kthread (kernel/kthread.c:292) [ 9.846271] ? __kthread_bind_mask (kernel/kthread.c:245) [ 9.846420] ret_from_fork (arch/x86/entry/entry_64.S:300) [ 9.846531] ---[ end trace 8b5647c1eba9d18a ]--- The problem occurs because in the non-hierarchical mode non-root page counters are not linked to root page counters, so the charge is not propagated to the root memory cgroup. After the removal of the original memory cgroup and reparenting of the object cgroup, the root cgroup might be uncharged by draining a objcg stock, for example. It leads to an eventual underflow of the charge and triggers a warning. Fix it by linking all page counters to corresponding root page counters in the non-hierarchical mode. Please note, that in the non-hierarchical mode all objcgs are always reparented to the root memory cgroup, even if the hierarchy has more than 1 level. This patch doesn't change it. The patch also doesn't affect how the hierarchical mode is working, which is the only sane and truly supported mode now. Thanks to Richard for reporting, debugging and providing an alternative version of the fix! Link: https://lkml.kernel.org/r/20201026231326.3212225-1-guro@fb.com Fixes: bf4f059954dc ("mm: memcg/slab: obj_cgroup API") Signed-off-by: Roman Gushchin Debugged-by: Richard Palethorpe Reported-by: Reviewed-by: Shakeel Butt Acked-by: Johannes Weiner Reviewed-by: Michal Koutný Cc: Michal Hocko Cc: Signed-off-by: Andrew Morton --- mm/memcontrol.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) --- a/mm/memcontrol.c~mm-memcg-link-page-counters-to-root-if-use_hierarchy-is-false +++ a/mm/memcontrol.c @@ -5345,17 +5345,22 @@ mem_cgroup_css_alloc(struct cgroup_subsy memcg->swappiness = mem_cgroup_swappiness(parent); memcg->oom_kill_disable = parent->oom_kill_disable; } - if (parent && parent->use_hierarchy) { + if (!parent) { + page_counter_init(&memcg->memory, NULL); + page_counter_init(&memcg->swap, NULL); + page_counter_init(&memcg->kmem, NULL); + page_counter_init(&memcg->tcpmem, NULL); + } else if (parent->use_hierarchy) { memcg->use_hierarchy = true; page_counter_init(&memcg->memory, &parent->memory); page_counter_init(&memcg->swap, &parent->swap); page_counter_init(&memcg->kmem, &parent->kmem); page_counter_init(&memcg->tcpmem, &parent->tcpmem); } else { - page_counter_init(&memcg->memory, NULL); - page_counter_init(&memcg->swap, NULL); - page_counter_init(&memcg->kmem, NULL); - page_counter_init(&memcg->tcpmem, NULL); + page_counter_init(&memcg->memory, &root_mem_cgroup->memory); + page_counter_init(&memcg->swap, &root_mem_cgroup->swap); + page_counter_init(&memcg->kmem, &root_mem_cgroup->kmem); + page_counter_init(&memcg->tcpmem, &root_mem_cgroup->tcpmem); /* * Deeper hierachy with use_hierarchy == false doesn't make * much sense so let cgroup subsystem know about this