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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 55AA3C2F3BE for ; Mon, 21 Jan 2019 14:01:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1D20921721 for ; Mon, 21 Jan 2019 14:01:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548079290; bh=yAKoL5eAz2mlQIAi9vT90JGukgQQt8cOoRZxEtNWkII=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=CqhnkaOxjtCmIn9BrG+hWKQyAQRZSw5jrvGifqIqAvO+QBNqYtPv8toMamy2W9Um0 brCseFgXtre6+pdisVTJEZxdEEe3v9cW8ncjIeHeKLheiXLo5mRyMRMq7R3SuPUFzv 44f49UIqIOFxdk/8oY/GVKFaCtIgz+s4g0OYZegY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731042AbfAUOB2 (ORCPT ); Mon, 21 Jan 2019 09:01:28 -0500 Received: from mail.kernel.org ([198.145.29.99]:48460 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729524AbfAUOBZ (ORCPT ); Mon, 21 Jan 2019 09:01:25 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (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 F244321019; Mon, 21 Jan 2019 14:01:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548079284; bh=yAKoL5eAz2mlQIAi9vT90JGukgQQt8cOoRZxEtNWkII=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cNRC6/7mc8drxdPdsJwhFXhyZ1fVZhrin8NxViZgC8rYy1FlwOHp7JlCm0mRf6bXo RuUnTgj4W6YvX5iSqqEP2rPeSOpPbQqQAYHod61AaWeKFu1y6EYXfT5c3eDH47d2PZ Dso5xzKSlZPZdwyW+RXPhXdhuCKHkyrFZDBcrB10= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Paul E. McKenney" , Yufen Yu , Jens Axboe Subject: [PATCH 4.19 70/99] block: use rcu_work instead of call_rcu to avoid sleep in softirq Date: Mon, 21 Jan 2019 14:49:02 +0100 Message-Id: <20190121134916.649485289@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190121134913.924726465@linuxfoundation.org> References: <20190121134913.924726465@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yufen Yu commit 94a2c3a32b62e868dc1e3d854326745a7f1b8c7a upstream. We recently got a stack by syzkaller like this: BUG: sleeping function called from invalid context at mm/slab.h:361 in_atomic(): 1, irqs_disabled(): 0, pid: 6644, name: blkid INFO: lockdep is turned off. CPU: 1 PID: 6644 Comm: blkid Not tainted 4.4.163-514.55.6.9.x86_64+ #76 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 0000000000000000 5ba6a6b879e50c00 ffff8801f6b07b10 ffffffff81cb2194 0000000041b58ab3 ffffffff833c7745 ffffffff81cb2080 5ba6a6b879e50c00 0000000000000000 0000000000000001 0000000000000004 0000000000000000 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0x114/0x1a0 lib/dump_stack.c:51 [] ___might_sleep+0x291/0x490 kernel/sched/core.c:7675 [] __might_sleep+0xb3/0x270 kernel/sched/core.c:7637 [] slab_pre_alloc_hook mm/slab.h:361 [inline] [] slab_alloc_node mm/slub.c:2610 [inline] [] slab_alloc mm/slub.c:2692 [inline] [] kmem_cache_alloc_trace+0x2c3/0x5c0 mm/slub.c:2709 [] kmalloc include/linux/slab.h:479 [inline] [] kzalloc include/linux/slab.h:623 [inline] [] kobject_uevent_env+0x2c7/0x1150 lib/kobject_uevent.c:227 [] kobject_uevent+0x1f/0x30 lib/kobject_uevent.c:374 [] kobject_cleanup lib/kobject.c:633 [inline] [] kobject_release+0x229/0x440 lib/kobject.c:675 [] kref_sub include/linux/kref.h:73 [inline] [] kref_put include/linux/kref.h:98 [inline] [] kobject_put+0x72/0xd0 lib/kobject.c:692 [] put_device+0x25/0x30 drivers/base/core.c:1237 [] delete_partition_rcu_cb+0x1d4/0x2f0 block/partition-generic.c:232 [] __rcu_reclaim kernel/rcu/rcu.h:118 [inline] [] rcu_do_batch kernel/rcu/tree.c:2705 [inline] [] invoke_rcu_callbacks kernel/rcu/tree.c:2973 [inline] [] __rcu_process_callbacks kernel/rcu/tree.c:2940 [inline] [] rcu_process_callbacks+0x59c/0x1c70 kernel/rcu/tree.c:2957 [] __do_softirq+0x299/0xe20 kernel/softirq.c:273 [] invoke_softirq kernel/softirq.c:350 [inline] [] irq_exit+0x216/0x2c0 kernel/softirq.c:391 [] exiting_irq arch/x86/include/asm/apic.h:652 [inline] [] smp_apic_timer_interrupt+0x8b/0xc0 arch/x86/kernel/apic/apic.c:926 [] apic_timer_interrupt+0xa5/0xb0 arch/x86/entry/entry_64.S:746 [] ? audit_kill_trees+0x180/0x180 [] fd_install+0x57/0x80 fs/file.c:626 [] do_sys_open+0x45e/0x550 fs/open.c:1043 [] SYSC_open fs/open.c:1055 [inline] [] SyS_open+0x32/0x40 fs/open.c:1050 [] entry_SYSCALL_64_fastpath+0x1e/0x9a In softirq context, we call rcu callback function delete_partition_rcu_cb(), which may allocate memory by kzalloc with GFP_KERNEL flag. If the allocation cannot be satisfied, it may sleep. However, That is not allowed in softirq contex. Although we found this problem on linux 4.4, the latest kernel version seems to have this problem as well. And it is very similar to the previous one: https://lkml.org/lkml/2018/7/9/391 Fix it by using RCU workqueue, which allows sleep. Reviewed-by: Paul E. McKenney Signed-off-by: Yufen Yu Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- block/partition-generic.c | 8 +++++--- include/linux/genhd.h | 2 +- 2 files changed, 6 insertions(+), 4 deletions(-) --- a/block/partition-generic.c +++ b/block/partition-generic.c @@ -249,9 +249,10 @@ struct device_type part_type = { .uevent = part_uevent, }; -static void delete_partition_rcu_cb(struct rcu_head *head) +static void delete_partition_work_fn(struct work_struct *work) { - struct hd_struct *part = container_of(head, struct hd_struct, rcu_head); + struct hd_struct *part = container_of(to_rcu_work(work), struct hd_struct, + rcu_work); part->start_sect = 0; part->nr_sects = 0; @@ -262,7 +263,8 @@ static void delete_partition_rcu_cb(stru void __delete_partition(struct percpu_ref *ref) { struct hd_struct *part = container_of(ref, struct hd_struct, ref); - call_rcu(&part->rcu_head, delete_partition_rcu_cb); + INIT_RCU_WORK(&part->rcu_work, delete_partition_work_fn); + queue_rcu_work(system_wq, &part->rcu_work); } /* --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -129,7 +129,7 @@ struct hd_struct { struct disk_stats dkstats; #endif struct percpu_ref ref; - struct rcu_head rcu_head; + struct rcu_work rcu_work; }; #define GENHD_FL_REMOVABLE 1