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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 E92A8C4742C for ; Sat, 31 Oct 2020 11:40:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A7B4620719 for ; Sat, 31 Oct 2020 11:40:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604144436; bh=GjZ94JZUrlTIYvnjyY/0fSyLXn6A2oYlycbxHDMPwx0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=iyh2rw7BTf7MTUFYv/21wzNafWnkDU5T/dDRlZQHwl/h8rvaPnom1dBHc4GsFRS1D nzo0mF1MXed5q7E5yjS/OYMpb7WxztZpIxUGEewWXqhOiEh+HnFomlQn+dT+9w9Hui V7cQ9D0kpAhaegWwm+0ClZw5Za2/EUcybJ7XcgFI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727434AbgJaLke (ORCPT ); Sat, 31 Oct 2020 07:40:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:38988 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727287AbgJaLkZ (ORCPT ); Sat, 31 Oct 2020 07:40:25 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 9AFEF20739; Sat, 31 Oct 2020 11:40:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604144424; bh=GjZ94JZUrlTIYvnjyY/0fSyLXn6A2oYlycbxHDMPwx0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a86KjxeOKWJLRDheN7jmwQndqm69DZZKQmShfyjO7nEgyDENMOxnplwcw5MmnwRRf nbFw7b1TSq7GSVRZzS8ZD2/J9Bo4R2k4N1pz+sPmd3RpqH9sRUhfa6F0ZN9seFVBmD yjcftpVRkN0uj770LwPXXBJR6Ta1Jb7YvRl3UsIU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, kernel test robot , Jens Axboe Subject: [PATCH 5.8 13/70] io_uring: no need to call xa_destroy() on empty xarray Date: Sat, 31 Oct 2020 12:35:45 +0100 Message-Id: <20201031113500.141316680@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201031113459.481803250@linuxfoundation.org> References: <20201031113459.481803250@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jens Axboe commit ca6484cd308a671811bf39f3119e81966eb476e3 upstream. The kernel test robot reports this lockdep issue: [child1:659] mbind (274) returned ENOSYS, marking as inactive. [child1:659] mq_timedsend (279) returned ENOSYS, marking as inactive. [main] 10175 iterations. [F:7781 S:2344 HI:2397] [ 24.610601] [ 24.610743] ================================ [ 24.611083] WARNING: inconsistent lock state [ 24.611437] 5.9.0-rc7-00017-g0f2122045b9462 #5 Not tainted [ 24.611861] -------------------------------- [ 24.612193] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. [ 24.612660] ksoftirqd/0/7 [HC0[0]:SC1[3]:HE0:SE0] takes: [ 24.613086] f00ed998 (&xa->xa_lock#4){+.?.}-{2:2}, at: xa_destroy+0x43/0xc1 [ 24.613642] {SOFTIRQ-ON-W} state was registered at: [ 24.614024] lock_acquire+0x20c/0x29b [ 24.614341] _raw_spin_lock+0x21/0x30 [ 24.614636] io_uring_add_task_file+0xe8/0x13a [ 24.614987] io_uring_create+0x535/0x6bd [ 24.615297] io_uring_setup+0x11d/0x136 [ 24.615606] __ia32_sys_io_uring_setup+0xd/0xf [ 24.615977] do_int80_syscall_32+0x53/0x6c [ 24.616306] restore_all_switch_stack+0x0/0xb1 [ 24.616677] irq event stamp: 939881 [ 24.616968] hardirqs last enabled at (939880): [<8105592d>] __local_bh_enable_ip+0x13c/0x145 [ 24.617642] hardirqs last disabled at (939881): [<81b6ace3>] _raw_spin_lock_irqsave+0x1b/0x4e [ 24.618321] softirqs last enabled at (939738): [<81b6c7c8>] __do_softirq+0x3f0/0x45a [ 24.618924] softirqs last disabled at (939743): [<81055741>] run_ksoftirqd+0x35/0x61 [ 24.619521] [ 24.619521] other info that might help us debug this: [ 24.620028] Possible unsafe locking scenario: [ 24.620028] [ 24.620492] CPU0 [ 24.620685] ---- [ 24.620894] lock(&xa->xa_lock#4); [ 24.621168] [ 24.621381] lock(&xa->xa_lock#4); [ 24.621695] [ 24.621695] *** DEADLOCK *** [ 24.621695] [ 24.622154] 1 lock held by ksoftirqd/0/7: [ 24.622468] #0: 823bfb94 (rcu_callback){....}-{0:0}, at: rcu_process_callbacks+0xc0/0x155 [ 24.623106] [ 24.623106] stack backtrace: [ 24.623454] CPU: 0 PID: 7 Comm: ksoftirqd/0 Not tainted 5.9.0-rc7-00017-g0f2122045b9462 #5 [ 24.624090] Call Trace: [ 24.624284] ? show_stack+0x40/0x46 [ 24.624551] dump_stack+0x1b/0x1d [ 24.624809] print_usage_bug+0x17a/0x185 [ 24.625142] mark_lock+0x11d/0x1db [ 24.625474] ? print_shortest_lock_dependencies+0x121/0x121 [ 24.625905] __lock_acquire+0x41e/0x7bf [ 24.626206] lock_acquire+0x20c/0x29b [ 24.626517] ? xa_destroy+0x43/0xc1 [ 24.626810] ? lock_acquire+0x20c/0x29b [ 24.627110] _raw_spin_lock_irqsave+0x3e/0x4e [ 24.627450] ? xa_destroy+0x43/0xc1 [ 24.627725] xa_destroy+0x43/0xc1 [ 24.627989] __io_uring_free+0x57/0x71 [ 24.628286] ? get_pid+0x22/0x22 [ 24.628544] __put_task_struct+0xf2/0x163 [ 24.628865] put_task_struct+0x1f/0x2a [ 24.629161] delayed_put_task_struct+0xe2/0xe9 [ 24.629509] rcu_process_callbacks+0x128/0x155 [ 24.629860] __do_softirq+0x1a3/0x45a [ 24.630151] run_ksoftirqd+0x35/0x61 [ 24.630443] smpboot_thread_fn+0x304/0x31a [ 24.630763] kthread+0x124/0x139 [ 24.631016] ? sort_range+0x18/0x18 [ 24.631290] ? kthread_create_worker_on_cpu+0x17/0x17 [ 24.631682] ret_from_fork+0x1c/0x28 which is complaining about xa_destroy() grabbing the xa lock in an IRQ disabling fashion, whereas the io_uring uses cases aren't interrupt safe. This is really an xarray issue, since it should not assume the lock type. But for our use case, since we know the xarray is empty at this point, there's no need to actually call xa_destroy(). So just get rid of it. Fixes: 0f2122045b94 ("io_uring: don't rely on weak ->files references") Reported-by: kernel test robot Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- fs/io_uring.c | 1 - 1 file changed, 1 deletion(-) --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -7136,7 +7136,6 @@ void __io_uring_free(struct task_struct struct io_uring_task *tctx = tsk->io_uring; WARN_ON_ONCE(!xa_empty(&tctx->xa)); - xa_destroy(&tctx->xa); kfree(tctx); tsk->io_uring = NULL; }