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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5C064C433EF for ; Wed, 30 Mar 2022 17:36:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349337AbiC3RiW (ORCPT ); Wed, 30 Mar 2022 13:38:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44190 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349336AbiC3RiP (ORCPT ); Wed, 30 Mar 2022 13:38:15 -0400 Received: from mail-io1-f70.google.com (mail-io1-f70.google.com [209.85.166.70]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 95D42B8202 for ; Wed, 30 Mar 2022 10:36:29 -0700 (PDT) Received: by mail-io1-f70.google.com with SMTP id u18-20020a5d8712000000b0064c7a7c497aso6079385iom.18 for ; Wed, 30 Mar 2022 10:36:29 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:date:message-id:subject:from:to; bh=NnWQsXw1ZTIntCkZPjGnAGxTYe0oZYJwswahLRe1MQY=; b=qt0M/JRkjQgsmQm1P8obl6jwECzjCWCBUW2NkND1qZIPokdMzdBXc513eu22mzyjgz GfO5qYYwgTFmBVPMAH0BcuuKipDKGXciMkUIkgTTNqsaqaAjkqyuWbhS5z8BnlTlnUC7 yQywFz+YDv+RPrlghhKqs3PuMJ40oo3Dz6lP4fkILs3oZROOwJvVR6Lt/Uq0PFyjJIB8 ZupqrTqnHK5knX8UJxOvSbC3vzJDdVpJUEkLmPlLY5a/E8IY06nghFMPIPGQ4d03rXcm /03nZ5StzfQwJhN1cFrupjAbHFGdnpp9faEfULklgC3N94Bp30qofSUdZ88YpbEyhVAO yW/w== X-Gm-Message-State: AOAM531mvnTQiISWiYuMzZlhzvm1Qx+cgfw5qmO8iYEbF+O2S5W8BsAw aDu7OGFdy/NgQAdaXhqcZU68kfRjzOtvsYNeeVS/vaoHfmzg X-Google-Smtp-Source: ABdhPJxTb1MD0lsR99SUT1yPR+FFFDpANVCDQZQ76AAtWRh4rtgb2h+MDJlMAQMlhXDXpdoRHjXfek1YqlsSUnHlIgDfd7eZChTh MIME-Version: 1.0 X-Received: by 2002:a05:6638:1918:b0:323:a4de:296 with SMTP id p24-20020a056638191800b00323a4de0296mr157592jal.212.1648661788910; Wed, 30 Mar 2022 10:36:28 -0700 (PDT) Date: Wed, 30 Mar 2022 10:36:28 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <00000000000048681f05db72fc45@google.com> Subject: [syzbot] possible deadlock in deactivate_super From: syzbot To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Hello, syzbot found the following issue on: HEAD commit: a67ba3cf9551 Add linux-next specific files for 20220330 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=10ab1377700000 kernel config: https://syzkaller.appspot.com/x/.config?x=994543c31e941639 dashboard link: https://syzkaller.appspot.com/bug?extid=df9d057e38be100ccbbe compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10b3d027700000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=159db307700000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+df9d057e38be100ccbbe@syzkaller.appspotmail.com RBP: 00007ffc747c2860 R08: 00000000ffffffff R09: 00007ffc747c2640 R10: 0000555555879653 R11: 0000000000000202 R12: 00007ffc747c38d0 R13: 00005555558795f0 R14: 00007ffc747c27d0 R15: 0000000000000001 ====================================================== WARNING: possible circular locking dependency detected 5.17.0-next-20220330-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor314/3590 is trying to acquire lock: ffff888010c64d38 ((wq_completion)events){+.+.}-{0:0}, at: flush_workqueue+0x135/0x1440 kernel/workqueue.c:2828 but task is already holding lock: ffff88801df760e0 (&type->s_umount_key#32){++++}-{3:3}, at: deactivate_super+0xa5/0xd0 fs/super.c:362 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&type->s_umount_key#32){++++}-{3:3}: down_read+0x98/0x440 kernel/locking/rwsem.c:1461 iterate_supers+0xdb/0x290 fs/super.c:692 drop_caches_sysctl_handler+0xdb/0x110 fs/drop_caches.c:62 proc_sys_call_handler+0x4a1/0x6e0 fs/proc/proc_sysctl.c:604 call_write_iter include/linux/fs.h:2080 [inline] do_iter_readv_writev+0x3d1/0x640 fs/read_write.c:726 do_iter_write+0x182/0x700 fs/read_write.c:852 vfs_iter_write+0x70/0xa0 fs/read_write.c:893 iter_file_splice_write+0x723/0xc70 fs/splice.c:689 do_splice_from fs/splice.c:767 [inline] direct_splice_actor+0x110/0x180 fs/splice.c:936 splice_direct_to_actor+0x34b/0x8c0 fs/splice.c:891 do_splice_direct+0x1a7/0x270 fs/splice.c:979 do_sendfile+0xae0/0x1240 fs/read_write.c:1246 __do_sys_sendfile64 fs/read_write.c:1305 [inline] __se_sys_sendfile64 fs/read_write.c:1297 [inline] __x64_sys_sendfile64+0x149/0x210 fs/read_write.c:1297 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #2 (sb_writers#3){.+.+}-{0:0}: percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1728 [inline] sb_start_write include/linux/fs.h:1798 [inline] file_start_write include/linux/fs.h:2815 [inline] kernel_write fs/read_write.c:564 [inline] kernel_write+0x2ac/0x540 fs/read_write.c:555 p9_fd_write net/9p/trans_fd.c:428 [inline] p9_write_work+0x25e/0xca0 net/9p/trans_fd.c:479 process_one_work+0x996/0x1610 kernel/workqueue.c:2289 worker_thread+0x665/0x1080 kernel/workqueue.c:2436 kthread+0x2e9/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 -> #1 ((work_completion)(&m->wq)){+.+.}-{0:0}: process_one_work+0x905/0x1610 kernel/workqueue.c:2265 worker_thread+0x665/0x1080 kernel/workqueue.c:2436 kthread+0x2e9/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 -> #0 ((wq_completion)events){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3096 [inline] check_prevs_add kernel/locking/lockdep.c:3219 [inline] validate_chain kernel/locking/lockdep.c:3834 [inline] __lock_acquire+0x2ac6/0x56c0 kernel/locking/lockdep.c:5060 lock_acquire kernel/locking/lockdep.c:5672 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5637 flush_workqueue+0x164/0x1440 kernel/workqueue.c:2831 flush_scheduled_work include/linux/workqueue.h:583 [inline] ext4_put_super+0x99/0x1150 fs/ext4/super.c:1202 generic_shutdown_super+0x14c/0x400 fs/super.c:462 kill_block_super+0x97/0xf0 fs/super.c:1394 deactivate_locked_super+0x94/0x160 fs/super.c:332 deactivate_super+0xad/0xd0 fs/super.c:363 cleanup_mnt+0x3a2/0x540 fs/namespace.c:1186 task_work_run+0xdd/0x1a0 kernel/task_work.c:164 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop kernel/entry/common.c:183 [inline] exit_to_user_mode_prepare+0x23c/0x250 kernel/entry/common.c:215 __syscall_exit_to_user_mode_work kernel/entry/common.c:297 [inline] syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:308 do_syscall_64+0x42/0x80 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae other info that might help us debug this: Chain exists of: (wq_completion)events --> sb_writers#3 --> &type->s_umount_key#32 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&type->s_umount_key#32); lock(sb_writers#3); lock(&type->s_umount_key#32); lock((wq_completion)events); *** DEADLOCK *** 1 lock held by syz-executor314/3590: #0: ffff88801df760e0 (&type->s_umount_key#32){++++}-{3:3}, at: deactivate_super+0xa5/0xd0 fs/super.c:362 stack backtrace: CPU: 1 PID: 3590 Comm: syz-executor314 Not tainted 5.17.0-next-20220330-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2176 check_prev_add kernel/locking/lockdep.c:3096 [inline] check_prevs_add kernel/locking/lockdep.c:3219 [inline] validate_chain kernel/locking/lockdep.c:3834 [inline] __lock_acquire+0x2ac6/0x56c0 kernel/locking/lockdep.c:5060 lock_acquire kernel/locking/lockdep.c:5672 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5637 flush_workqueue+0x164/0x1440 kernel/workqueue.c:2831 flush_scheduled_work include/linux/workqueue.h:583 [inline] ext4_put_super+0x99/0x1150 fs/ext4/super.c:1202 generic_shutdown_super+0x14c/0x400 fs/super.c:462 kill_block_super+0x97/0xf0 fs/super.c:1394 deactivate_locked_super+0x94/0x160 fs/super.c:332 deactivate_super+0xad/0xd0 fs/super.c:363 cleanup_mnt+0x3a2/0x540 fs/namespace.c:1186 task_work_run+0xdd/0x1a0 kernel/task_work.c:164 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop kernel/entry/common.c:183 [inline] exit_to_user_mode_prepare+0x23c/0x250 kernel/entry/common.c:215 __syscall_exit_to_user_mode_work kernel/entry/common.c:297 [inline] syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:308 do_syscall_64+0x42/0x80 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f2437452687 Code: 07 00 48 83 c4 08 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffc747c27a8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f2437452687 RDX: 00007ffc747c2869 RSI: 000000000000000a RDI: 00007ffc747c2860 RBP: 00007ffc747c2860 R08: 00000000ffffffff R09: 00007ffc747c2640 R10: 0000555555879653 R11: 0000000000000202 R12: 00007ffc747c38d0 R13: 00005555558795f0 R14: 00007ffc747c27d0 R15: 0000000000000001 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. syzbot can test patches for this issue, for details see: https://goo.gl/tpsmEJ#testing-patches