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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9CE44C433F5 for ; Thu, 11 Nov 2021 09:51:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 84E3161152 for ; Thu, 11 Nov 2021 09:51:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232777AbhKKJyH (ORCPT ); Thu, 11 Nov 2021 04:54:07 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:16248 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S232611AbhKKJyF (ORCPT ); Thu, 11 Nov 2021 04:54:05 -0500 Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 1AB8hchF015946; Thu, 11 Nov 2021 09:50:32 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding; s=pp1; bh=9yzO3BN01R+xwzrsYOarJeAaAZRR7/sSADKUU1/AwUU=; b=Yl4IkLQNpU6cT1gSgFFV6IAdZVQrcTtnIFH5kKUQlEnhSvo43hIMII+rQQXAbvmFgs6U 6/HM5mvAkv0qcelGhlsRBZiMScPoN/KbG2m3acmmEUOwseqlehFkGza/EDOUTbvMPZSJ GQiCvVHFYCMGwOMVe30zmi13ohNxiSGQl0PLrWU6kXNxaOAkJqpJXyIAhLtxtL6H8WlE 9WxN5wcmYtVL0iGmumqRxDVN8QMQn9A2sY+CKYMCPuoUlqPyK9YusvAf/Bmo53PulagS pffpwXxsl4tbv1ZjD+e5h99ii/CuWPmbWn/aEq3PK7n0oQhp5DeUPXRrMgjLGOxDaYJO MA== Received: from pps.reinject (localhost [127.0.0.1]) by mx0b-001b2d01.pphosted.com with ESMTP id 3c8ywvskb4-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 11 Nov 2021 09:50:31 +0000 Received: from m0098420.ppops.net (m0098420.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 1AB9Gt3v000675; Thu, 11 Nov 2021 09:50:31 GMT Received: from ppma03fra.de.ibm.com (6b.4a.5195.ip4.static.sl-reverse.com [149.81.74.107]) by mx0b-001b2d01.pphosted.com with ESMTP id 3c8ywvska3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 11 Nov 2021 09:50:31 +0000 Received: from pps.filterd (ppma03fra.de.ibm.com [127.0.0.1]) by ppma03fra.de.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 1AB9nJmM003941; Thu, 11 Nov 2021 09:50:29 GMT Received: from b06cxnps3075.portsmouth.uk.ibm.com (d06relay10.portsmouth.uk.ibm.com [9.149.109.195]) by ppma03fra.de.ibm.com with ESMTP id 3c5hbasbxr-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 11 Nov 2021 09:50:29 +0000 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 1AB9oOxx51052872 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 11 Nov 2021 09:50:24 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D8E9A4C05C; Thu, 11 Nov 2021 09:50:23 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B7A734C066; Thu, 11 Nov 2021 09:50:22 +0000 (GMT) Received: from localhost.localdomain (unknown [9.145.11.147]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 11 Nov 2021 09:50:22 +0000 (GMT) From: Claudio Imbrenda To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: thuth@redhat.com, frankja@linux.ibm.com, borntraeger@de.ibm.com, Ulrich.Weigand@de.ibm.com, heiko.carstens@de.ibm.com, david@redhat.com, ultrachin@163.com, akpm@linux-foundation.org, vbabka@suse.cz, brookxu.cn@gmail.com, xiaoggchen@tencent.com, linuszeng@tencent.com, yihuilu@tencent.com, mhocko@suse.com, daniel.m.jordan@oracle.com, axboe@kernel.dk, legion@kernel.org, peterz@infradead.org, aarcange@redhat.com, christian@brauner.io, ebiederm@xmission.com, tglx@linutronix.de Subject: [RFC v1 4/4] kernel/fork.c: process_mmput_async: stop OOM while freeing memory Date: Thu, 11 Nov 2021 10:50:08 +0100 Message-Id: <20211111095008.264412-6-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211111095008.264412-1-imbrenda@linux.ibm.com> References: <20211111095008.264412-1-imbrenda@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: B7S9vjvRQblh7Daa7g2JMtqFHEdIVmw4 X-Proofpoint-ORIG-GUID: JJjGFKWaQASuTc3y7iLoJeuCTRReAybx X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.0.607.475 definitions=2021-11-11_02,2021-11-08_02,2020-04-07_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 malwarescore=0 mlxlogscore=999 impostorscore=0 mlxscore=0 lowpriorityscore=0 phishscore=0 spamscore=0 clxscore=1015 priorityscore=1501 suspectscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2111110056 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch implements a simple OOM notifier to stop the OOM killer while a mm is being reclaimed asynchronously using the process_mmput_async syscall. Tested on s390x. Signed-off-by: Claudio Imbrenda --- kernel/fork.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/kernel/fork.c b/kernel/fork.c index 0da39b76005c..7279209eb69c 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -118,6 +118,11 @@ */ #define MAX_THREADS FUTEX_TID_MASK +/* + * Priority for the OOM notifier used in process_mmput_async + */ +#define PROCESS_MMPUT_ASYNC_OOM_NOTIFY_PRIORITY 70 + /* * Protected counters by write_lock_irq(&tasklist_lock) */ @@ -3203,13 +3208,27 @@ int sysctl_max_threads(struct ctl_table *table, int write, return 0; } +/* Prevent the OOM from being triggered while we are cleaning up asynchronously */ +static int mmput_async_oom_notifier(struct notifier_block *nb, unsigned long dummy, void *parm) +{ + /* + * We cannot know the speed at which pages are being freed, so we + * fake it and say it's at least one. This is already enough to + * stop the OOM killer. + */ + *(unsigned long *)parm += PAGE_SIZE; + return NOTIFY_OK; +} + SYSCALL_DEFINE2(process_mmput_async, int, pidfd, unsigned int, flags) { #ifdef CONFIG_MMU + struct notifier_block oom_nb; struct mm_struct *mm = NULL; struct task_struct *task; unsigned int tmp; struct pid *pid; + int r; if (flags) return -EINVAL; @@ -3280,8 +3299,17 @@ SYSCALL_DEFINE2(process_mmput_async, int, pidfd, unsigned int, flags) if (atomic_read(&mm->mm_users)) panic("mm_users not 0 but trying to __mmput anyway!"); + /* + * Register an OOM notifier, to stop the OOM while we are + * asynchronously freeing the mm. + */ + oom_nb.priority = PROCESS_MMPUT_ASYNC_OOM_NOTIFY_PRIORITY; + oom_nb.notifier_call = mmput_async_oom_notifier; + r = register_oom_notifier(&oom_nb); /* Do the actual work */ __mmput(mm); + if (!r) + unregister_oom_notifier(&oom_nb); /* And put the extra reference taken above */ mmdrop(mm); -- 2.31.1