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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E6757EB64DA for ; Sun, 16 Jul 2023 10:06:18 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=s/nCZJyq; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4R3gpd2dXjz3c13 for ; Sun, 16 Jul 2023 20:06:17 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=s/nCZJyq; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.ibm.com (client-ip=148.163.158.5; helo=mx0b-001b2d01.pphosted.com; envelope-from=haren@linux.ibm.com; receiver=lists.ozlabs.org) Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4R3gnb5XSkz30fF for ; Sun, 16 Jul 2023 20:05:23 +1000 (AEST) Received: from pps.filterd (m0353723.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 36G9kaqs015139; Sun, 16 Jul 2023 10:05:15 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding; s=pp1; bh=YOv08gZ3Gl/29VU7Mm5/WhFKSB1jBdQwzywQT/bu5EY=; b=s/nCZJyqOwEc9iAyzo2Gh6PrFJwta4QWEROU2umBiBkBoK2RyLoYc0uMo++nmd1Y81Dz tZMiwlTMULURm0h0i0X60nq/nw0G/Og2S0DjJB/NuV5ND9kimpb0LURxK6G9etq8gGUJ 9pyd7cGAOkHeedPGSsgikM9FJ6ZtiT+4xfeFy0vmOE3Qa39F/GWXcaq9Jt8x2/BwtCz0 oUZRlHiZYnlIpvXmCBvY8JCVniuFYa+tvwh04wV2aNLtMKymTmoIRIRpt96mep3+0owk lzuGaIytYjcI3FgzC7h3y5Tg2CTbwFMA4RZt/ZmFYXPIsgkay33wFw9L5typNEhWw/Pl EQ== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3rve7dg89x-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sun, 16 Jul 2023 10:05:15 +0000 Received: from m0353723.ppops.net (m0353723.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 36GA0Sl4010420; Sun, 16 Jul 2023 10:05:14 GMT Received: from ppma04dal.us.ibm.com (7a.29.35a9.ip4.static.sl-reverse.com [169.53.41.122]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3rve7dg898-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sun, 16 Jul 2023 10:05:14 +0000 Received: from pps.filterd (ppma04dal.us.ibm.com [127.0.0.1]) by ppma04dal.us.ibm.com (8.17.1.19/8.17.1.19) with ESMTP id 36G9vFVT002885; Sun, 16 Jul 2023 10:05:14 GMT Received: from smtprelay07.dal12v.mail.ibm.com ([9.208.130.99]) by ppma04dal.us.ibm.com (PPS) with ESMTPS id 3ruk358yyv-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sun, 16 Jul 2023 10:05:14 +0000 Received: from smtpav03.wdc07v.mail.ibm.com (smtpav03.wdc07v.mail.ibm.com [10.39.53.230]) by smtprelay07.dal12v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 36GA5CnC22085988 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 16 Jul 2023 10:05:12 GMT Received: from smtpav03.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E88E75805A; Sun, 16 Jul 2023 10:05:11 +0000 (GMT) Received: from smtpav03.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4345658054; Sun, 16 Jul 2023 10:05:10 +0000 (GMT) Received: from localhost.ibm.com (unknown [9.67.80.155]) by smtpav03.wdc07v.mail.ibm.com (Postfix) with ESMTP; Sun, 16 Jul 2023 10:05:10 +0000 (GMT) From: Haren Myneni To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH v2] powerpc/pseries/vas: Hold mmap_mutex after mmap lock during window close Date: Sun, 16 Jul 2023 03:05:06 -0700 Message-Id: <20230716100506.7833-1-haren@linux.ibm.com> X-Mailer: git-send-email 2.26.3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: DyT7s9dJZYW9oo00I-rjO9IovZnHrUGo X-Proofpoint-GUID: tdqAjiaiWiK0bgOwUeFWT2FjBDVzUxOT X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.957,Hydra:6.0.591,FMLib:17.11.176.26 definitions=2023-07-15_14,2023-07-13_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 mlxscore=0 impostorscore=0 mlxlogscore=999 lowpriorityscore=0 adultscore=0 suspectscore=0 bulkscore=0 clxscore=1015 malwarescore=0 phishscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2306200000 definitions=main-2307160093 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: nathanl@linux.ibm.com, Haren Myneni , npiggin@gmail.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Commit 8ef7b9e1765a ("powerpc/pseries/vas: Close windows with DLPAR core removal") unmaps the window paste address and issues HCALL to close window in the hypervisor for migration or DLPAR core removal events. So holds mmap_mutex and then mmap lock before unmap the paste address. But if the user space issue mmap paste address at the same time with the migration event, coproc_mmap() is called after holding the mmap lock which can trigger deadlock when trying to acquire mmap_mutex in coproc_mmap(). t1: mmap() call to mmap t2: Migration event window paste address do_mmap2() migration_store() ksys_mmap_pgoff() pseries_migrate_partition() vm_mmap_pgoff() vas_migration_handler() Acquire mmap lock reconfig_close_windows() do_mmap() lock mmap_mutex mmap_region() Acquire mmap lock call_mmap() //Wait for mmap lock coproc_mmap() unmap vma lock mmap_mutex update window status //wait for mmap_mutex Release mmap lock mmap vma unlock mmap_mutex update window status unlock mmap_mutex ... Release mmap lock Fix this deadlock issue by holding mmap lock first before mmap_mutex in reconfig_close_windows(). Fixes: 8ef7b9e1765a ("powerpc/pseries/vas: Close windows with DLPAR core removal") Signed-off-by: Haren Myneni --- Changes from v1: - Update commit log with more description on deadlock traces --- arch/powerpc/platforms/pseries/vas.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/platforms/pseries/vas.c b/arch/powerpc/platforms/pseries/vas.c index 513180467562..15d958e38eca 100644 --- a/arch/powerpc/platforms/pseries/vas.c +++ b/arch/powerpc/platforms/pseries/vas.c @@ -744,6 +744,12 @@ static int reconfig_close_windows(struct vas_caps *vcap, int excess_creds, } task_ref = &win->vas_win.task_ref; + /* + * VAS mmap (coproc_mmap()) and its fault handler + * (vas_mmap_fault()) are called after holding mmap lock. + * So hold mmap mutex after mmap_lock to avoid deadlock. + */ + mmap_write_lock(task_ref->mm); mutex_lock(&task_ref->mmap_mutex); vma = task_ref->vma; /* @@ -752,7 +758,6 @@ static int reconfig_close_windows(struct vas_caps *vcap, int excess_creds, */ win->vas_win.status |= flag; - mmap_write_lock(task_ref->mm); /* * vma is set in the original mapping. But this mapping * is done with mmap() after the window is opened with ioctl. @@ -762,8 +767,8 @@ static int reconfig_close_windows(struct vas_caps *vcap, int excess_creds, if (vma) zap_vma_pages(vma); - mmap_write_unlock(task_ref->mm); mutex_unlock(&task_ref->mmap_mutex); + mmap_write_unlock(task_ref->mm); /* * Close VAS window in the hypervisor, but do not * free vas_window struct since it may be reused -- 2.26.3