From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DC2091519B4; Wed, 5 Feb 2025 15:12:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738768353; cv=none; b=Xy8O4ojfZ5JZoLEwXcJ6gPHQ5O4nkLGfNq/qeSxMZz9/e459SBiLFK0R8dO9IIlibSghUlCSytMjd9eqREj45DoTKsAhFqyVukDK7lfL/fJ7BLTCQCx7bOVRbStOyY6fShSWUcOtmQlFQoAZo0za9/eyAHv+4C9EkIVb+n929Fg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738768353; c=relaxed/simple; bh=80rq5VqsQV4NK5LIp4qEgOaVjyr2xJBS6qpRbRATbzw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=WHNXb7FI6bopxABd66Ex9iY7M4Qo3fWDK+4fWCNBG1lyeKLEgsAdmUTceSHDIN7h0ctR6dRWX2fnJtBo88UzDUCLprEYpIQn89vH9R0QhEkayKrnzBE8C6M3OfSeR0svq9/emnhZHN/lVrg/SvqgcpwretImRhFqvmsqXr2yGwc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Or8GorRx; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Or8GorRx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 49E0CC4CED1; Wed, 5 Feb 2025 15:12:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1738768352; bh=80rq5VqsQV4NK5LIp4qEgOaVjyr2xJBS6qpRbRATbzw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Or8GorRxwKQraPc68tRM15fDz8Hw8CiZVG2Kk7ynMsRnezsw5eLacHo0VU1XqOp/w PLfcA7ib/hfk4jMdn6n47UvinYKPqREdtgyZ29ADdfKQDXLG+My3i6D96ZEMd2HKMI yS5+UTlSLNzm3JPpwGHMMZMTuOQIw2C3gii3VBrc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chen Ridong , Michal Hocko , Roman Gushchin , Johannes Weiner , Shakeel Butt , Muchun Song , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Andrew Morton Subject: [PATCH 6.12 588/590] memcg: fix soft lockup in the OOM process Date: Wed, 5 Feb 2025 14:45:43 +0100 Message-ID: <20250205134517.757237328@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250205134455.220373560@linuxfoundation.org> References: <20250205134455.220373560@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chen Ridong commit ade81479c7dda1ce3eedb215c78bc615bbd04f06 upstream. A soft lockup issue was found in the product with about 56,000 tasks were in the OOM cgroup, it was traversing them when the soft lockup was triggered. watchdog: BUG: soft lockup - CPU#2 stuck for 23s! [VM Thread:1503066] CPU: 2 PID: 1503066 Comm: VM Thread Kdump: loaded Tainted: G Hardware name: Huawei Cloud OpenStack Nova, BIOS RIP: 0010:console_unlock+0x343/0x540 RSP: 0000:ffffb751447db9a0 EFLAGS: 00000247 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 00000000ffffffff RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000247 RBP: ffffffffafc71f90 R08: 0000000000000000 R09: 0000000000000040 R10: 0000000000000080 R11: 0000000000000000 R12: ffffffffafc74bd0 R13: ffffffffaf60a220 R14: 0000000000000247 R15: 0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f2fe6ad91f0 CR3: 00000004b2076003 CR4: 0000000000360ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: vprintk_emit+0x193/0x280 printk+0x52/0x6e dump_task+0x114/0x130 mem_cgroup_scan_tasks+0x76/0x100 dump_header+0x1fe/0x210 oom_kill_process+0xd1/0x100 out_of_memory+0x125/0x570 mem_cgroup_out_of_memory+0xb5/0xd0 try_charge+0x720/0x770 mem_cgroup_try_charge+0x86/0x180 mem_cgroup_try_charge_delay+0x1c/0x40 do_anonymous_page+0xb5/0x390 handle_mm_fault+0xc4/0x1f0 This is because thousands of processes are in the OOM cgroup, it takes a long time to traverse all of them. As a result, this lead to soft lockup in the OOM process. To fix this issue, call 'cond_resched' in the 'mem_cgroup_scan_tasks' function per 1000 iterations. For global OOM, call 'touch_softlockup_watchdog' per 1000 iterations to avoid this issue. Link: https://lkml.kernel.org/r/20241224025238.3768787-1-chenridong@huaweicloud.com Fixes: 9cbb78bb3143 ("mm, memcg: introduce own oom handler to iterate only over its own threads") Signed-off-by: Chen Ridong Acked-by: Michal Hocko Cc: Roman Gushchin Cc: Johannes Weiner Cc: Shakeel Butt Cc: Muchun Song Cc: Michal Koutný Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- mm/memcontrol.c | 7 ++++++- mm/oom_kill.c | 8 +++++++- 2 files changed, 13 insertions(+), 2 deletions(-) --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1139,6 +1139,7 @@ void mem_cgroup_scan_tasks(struct mem_cg { struct mem_cgroup *iter; int ret = 0; + int i = 0; BUG_ON(mem_cgroup_is_root(memcg)); @@ -1147,8 +1148,12 @@ void mem_cgroup_scan_tasks(struct mem_cg struct task_struct *task; css_task_iter_start(&iter->css, CSS_TASK_ITER_PROCS, &it); - while (!ret && (task = css_task_iter_next(&it))) + while (!ret && (task = css_task_iter_next(&it))) { + /* Avoid potential softlockup warning */ + if ((++i & 1023) == 0) + cond_resched(); ret = fn(task, arg); + } css_task_iter_end(&it); if (ret) { mem_cgroup_iter_break(memcg, iter); --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -45,6 +45,7 @@ #include #include #include +#include #include #include "internal.h" @@ -431,10 +432,15 @@ static void dump_tasks(struct oom_contro mem_cgroup_scan_tasks(oc->memcg, dump_task, oc); else { struct task_struct *p; + int i = 0; rcu_read_lock(); - for_each_process(p) + for_each_process(p) { + /* Avoid potential softlockup warning */ + if ((++i & 1023) == 0) + touch_softlockup_watchdog(); dump_task(p, oc); + } rcu_read_unlock(); } }