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=-5.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 2D21BC43331 for ; Fri, 3 Apr 2020 09:11:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F1E8920787 for ; Fri, 3 Apr 2020 09:11:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="e2NAo1ga" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390477AbgDCJLu (ORCPT ); Fri, 3 Apr 2020 05:11:50 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:21549 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2388221AbgDCJLu (ORCPT ); Fri, 3 Apr 2020 05:11:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585905109; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=TIhasx7mfHmhChZxkyzVH37c41A+dmsixY6NsWrnvsA=; b=e2NAo1gaQV1C6VY0JWPGj8V8plTd7DqM10nK6pogmXk7PcgzabjofkZz6dqc2MVDyKHUME wqySze71CT3lAq3d8/AW6mEFnXsKMEiAT0wb9xnNP1Wkr4UjiVNmTb+hdiFNHUOmkzraW6 W8urrwwk/j5eDCDdtLFydOjt2WPx+Ik= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-184-PZEwFqdQPl6ImvTESWcrBg-1; Fri, 03 Apr 2020 05:11:47 -0400 X-MC-Unique: PZEwFqdQPl6ImvTESWcrBg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8741D477; Fri, 3 Apr 2020 09:11:43 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.193.202]) by smtp.corp.redhat.com (Postfix) with SMTP id DAB7A50BEE; Fri, 3 Apr 2020 09:11:36 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 3 Apr 2020 11:11:43 +0200 (CEST) Date: Fri, 3 Apr 2020 11:11:35 +0200 From: Oleg Nesterov To: syzbot Cc: adobriyan@gmail.com, akpm@linux-foundation.org, allison@lohutok.net, areber@redhat.com, aubrey.li@linux.intel.com, avagin@gmail.com, bfields@fieldses.org, christian@brauner.io, cyphar@cyphar.com, ebiederm@xmission.com, gregkh@linuxfoundation.org, guro@fb.com, jlayton@kernel.org, joel@joelfernandes.org, keescook@chromium.org, linmiaohe@huawei.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, mhocko@suse.com, mingo@kernel.org, peterz@infradead.org, sargun@sargun.me, syzkaller-bugs@googlegroups.com, tglx@linutronix.de, viro@zeniv.linux.org.uk Subject: Re: possible deadlock in send_sigurg Message-ID: <20200403091135.GA3645@redhat.com> References: <00000000000011d66805a25cd73f@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <00000000000011d66805a25cd73f@google.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 04/02, syzbot wrote: > > lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923 > __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] > _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151 > spin_lock include/linux/spinlock.h:353 [inline] > proc_pid_make_inode+0x1f9/0x3c0 fs/proc/base.c:1880 Yes, spin_lock(wait_pidfd.lock) is not safe... Eric, at first glance the fix is simple. Oleg. diff --git a/fs/proc/base.c b/fs/proc/base.c index 74f948a6b621..9ec8c114aa60 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1839,9 +1839,9 @@ void proc_pid_evict_inode(struct proc_inode *ei) struct pid *pid = ei->pid; if (S_ISDIR(ei->vfs_inode.i_mode)) { - spin_lock(&pid->wait_pidfd.lock); + spin_lock_irq(&pid->wait_pidfd.lock); hlist_del_init_rcu(&ei->sibling_inodes); - spin_unlock(&pid->wait_pidfd.lock); + spin_unlock_irq(&pid->wait_pidfd.lock); } put_pid(pid); @@ -1877,9 +1877,9 @@ struct inode *proc_pid_make_inode(struct super_block * sb, /* Let the pid remember us for quick removal */ ei->pid = pid; if (S_ISDIR(mode)) { - spin_lock(&pid->wait_pidfd.lock); + spin_lock_irq(&pid->wait_pidfd.lock); hlist_add_head_rcu(&ei->sibling_inodes, &pid->inodes); - spin_unlock(&pid->wait_pidfd.lock); + spin_unlock_irq(&pid->wait_pidfd.lock); } task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid); diff --git a/fs/proc/inode.c b/fs/proc/inode.c index 1e730ea1dcd6..6b7ee76e1b36 100644 --- a/fs/proc/inode.c +++ b/fs/proc/inode.c @@ -123,9 +123,9 @@ void proc_invalidate_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock if (!node) break; ei = hlist_entry(node, struct proc_inode, sibling_inodes); - spin_lock(lock); + spin_lock_irq(lock); hlist_del_init_rcu(&ei->sibling_inodes); - spin_unlock(lock); + spin_unlock_irq(lock); inode = &ei->vfs_inode; sb = inode->i_sb;