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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 E2057C433E0 for ; Thu, 18 Feb 2021 18:52:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9234564EB7 for ; Thu, 18 Feb 2021 18:52:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232009AbhBRSvt (ORCPT ); Thu, 18 Feb 2021 13:51:49 -0500 Received: from out30-57.freemail.mail.aliyun.com ([115.124.30.57]:42370 "EHLO out30-57.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233953AbhBRRR4 (ORCPT ); Thu, 18 Feb 2021 12:17:56 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R141e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04423;MF=haoxu@linux.alibaba.com;NM=1;PH=DS;RN=3;SR=0;TI=SMTPD_---0UOunQbh_1613668616; Received: from B-25KNML85-0107.local(mailfrom:haoxu@linux.alibaba.com fp:SMTPD_---0UOunQbh_1613668616) by smtp.aliyun-inc.com(127.0.0.1); Fri, 19 Feb 2021 01:16:56 +0800 Subject: Re: [PATCH] io_uring: don't recursively hold ctx->uring_lock in io_wq_submit_work() To: Jens Axboe Cc: io-uring@vger.kernel.org, Joseph Qi References: <1611394824-73078-1-git-send-email-haoxu@linux.alibaba.com> <45a0221a-bd2b-7183-e35d-2d2550f687b5@kernel.dk> From: Hao Xu Message-ID: Date: Fri, 19 Feb 2021 01:16:56 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <45a0221a-bd2b-7183-e35d-2d2550f687b5@kernel.dk> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org 在 2021/1/25 下午12:31, Jens Axboe 写道: > On 1/23/21 2:40 AM, Hao Xu wrote: >> Abaci reported the following warning: >> >> [ 97.862205] ============================================ >> [ 97.863400] WARNING: possible recursive locking detected >> [ 97.864640] 5.11.0-rc4+ #12 Not tainted >> [ 97.865537] -------------------------------------------- >> [ 97.866748] a.out/2890 is trying to acquire lock: >> [ 97.867829] ffff8881046763e8 (&ctx->uring_lock){+.+.}-{3:3}, at: >> io_wq_submit_work+0x155/0x240 >> [ 97.869735] >> [ 97.869735] but task is already holding lock: >> [ 97.871033] ffff88810dfe0be8 (&ctx->uring_lock){+.+.}-{3:3}, at: >> __x64_sys_io_uring_enter+0x3f0/0x5b0 >> [ 97.873074] >> [ 97.873074] other info that might help us debug this: >> [ 97.874520] Possible unsafe locking scenario: >> [ 97.874520] >> [ 97.875845] CPU0 >> [ 97.876440] ---- >> [ 97.877048] lock(&ctx->uring_lock); >> [ 97.877961] lock(&ctx->uring_lock); >> [ 97.878881] >> [ 97.878881] *** DEADLOCK *** >> [ 97.878881] >> [ 97.880341] May be due to missing lock nesting notation >> [ 97.880341] >> [ 97.881952] 1 lock held by a.out/2890: >> [ 97.882873] #0: ffff88810dfe0be8 (&ctx->uring_lock){+.+.}-{3:3}, at: >> __x64_sys_io_uring_enter+0x3f0/0x5b0 >> [ 97.885108] >> [ 97.885108] stack backtrace: >> [ 97.886209] CPU: 0 PID: 2890 Comm: a.out Not tainted 5.11.0-rc4+ #12 >> [ 97.887683] Hardware name: Alibaba Cloud Alibaba Cloud ECS, BIOS >> rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014 >> [ 97.890457] Call Trace: >> [ 97.891121] dump_stack+0xac/0xe3 >> [ 97.891972] __lock_acquire+0xab6/0x13a0 >> [ 97.892940] lock_acquire+0x2c3/0x390 >> [ 97.893853] ? io_wq_submit_work+0x155/0x240 >> [ 97.894894] __mutex_lock+0xae/0x9f0 >> [ 97.895785] ? io_wq_submit_work+0x155/0x240 >> [ 97.896816] ? __lock_acquire+0x782/0x13a0 >> [ 97.897817] ? io_wq_submit_work+0x155/0x240 >> [ 97.898867] ? io_wq_submit_work+0x155/0x240 >> [ 97.899916] ? _raw_spin_unlock_irqrestore+0x2d/0x40 >> [ 97.901101] io_wq_submit_work+0x155/0x240 >> [ 97.902112] io_wq_cancel_cb+0x162/0x490 >> [ 97.903084] ? io_uring_get_socket+0x40/0x40 >> [ 97.904126] io_async_find_and_cancel+0x3b/0x140 >> [ 97.905247] io_issue_sqe+0x86d/0x13e0 >> [ 97.906186] ? __lock_acquire+0x782/0x13a0 >> [ 97.907195] ? __io_queue_sqe+0x10b/0x550 >> [ 97.908175] ? lock_acquire+0x2c3/0x390 >> [ 97.909122] __io_queue_sqe+0x10b/0x550 >> [ 97.910080] ? io_req_prep+0xd8/0x1090 >> [ 97.911044] ? mark_held_locks+0x5a/0x80 >> [ 97.912042] ? mark_held_locks+0x5a/0x80 >> [ 97.913014] ? io_queue_sqe+0x235/0x470 >> [ 97.913971] io_queue_sqe+0x235/0x470 >> [ 97.914894] io_submit_sqes+0xcce/0xf10 >> [ 97.915842] ? xa_store+0x3b/0x50 >> [ 97.916683] ? __x64_sys_io_uring_enter+0x3f0/0x5b0 >> [ 97.917872] __x64_sys_io_uring_enter+0x3fb/0x5b0 >> [ 97.918995] ? lockdep_hardirqs_on_prepare+0xde/0x180 >> [ 97.920204] ? syscall_enter_from_user_mode+0x26/0x70 >> [ 97.921424] do_syscall_64+0x2d/0x40 >> [ 97.922329] entry_SYSCALL_64_after_hwframe+0x44/0xa9 >> [ 97.923538] RIP: 0033:0x7f0b62601239 >> [ 97.924437] Code: 01 00 48 81 c4 80 00 00 00 e9 f1 fe ff ff 0f 1f 00 >> 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f >> 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 27 ec 2c 00 f7 d8 64 89 01 >> 48 >> [ 97.928628] RSP: 002b:00007f0b62cc4d28 EFLAGS: 00000246 ORIG_RAX: >> 00000000000001aa >> [ 97.930422] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: >> 00007f0b62601239 >> [ 97.932073] RDX: 0000000000000000 RSI: 0000000000006cf6 RDI: >> 0000000000000005 >> [ 97.933710] RBP: 00007f0b62cc4e20 R08: 0000000000000000 R09: >> 0000000000000000 >> [ 97.935369] R10: 0000000000000000 R11: 0000000000000246 R12: >> 0000000000000000 >> [ 97.937008] R13: 0000000000021000 R14: 0000000000000000 R15: >> 00007f0b62cc5700 >> >> This is caused by try to hold uring_lock in io_wq_submit_work() without >> checking if we are in io-wq thread context or not. It can be in original >> context when io_wq_submit_work() is called from IORING_OP_ASYNC_CANCEL >> code path, where we already held uring_lock. > > Looks like another fallout of the split CLOSE handling. I've got the > right fixes pending for 5.12: > > https://git.kernel.dk/cgit/linux-block/commit/?h=for-5.12/io_uring&id=6bb0079ef3420041886afe1bcd8e7a87e08992e1 > > (and the prep patch before that in the tree). But that won't really > help us for 5.11 and earlier, though we probably should just queue > those two patches for 5.11 and get them into stable. I really don't > like the below patch, though it should fix it. But the root cause > is really the weird open cancelation... > Hi Jens, I've repro-ed this issue on branch for-5.12/io_uring-2021-02-17 which contains the patch you give, the issue still exists. I think this one is not an async close specifical problem. The rootcause is we try to run an iowq work in the original context(queue an iowq work, then async cancel it). Thanks, Hao