From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752264AbeECKRL (ORCPT ); Thu, 3 May 2018 06:17:11 -0400 Received: from mail-it0-f69.google.com ([209.85.214.69]:33566 "EHLO mail-it0-f69.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751765AbeECKRC (ORCPT ); Thu, 3 May 2018 06:17:02 -0400 X-Google-Smtp-Source: AB8JxZrr0Sed9Mc1e0eHoorszlUE/VkpAgI0QHNkrVOGtN6j/J9NKq7Eauw2kDDdY/dLHz1dLRcGopDi64u1tZv/I3qpOA5Gw2aa MIME-Version: 1.0 Date: Thu, 03 May 2018 03:17:02 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <000000000000283c37056b4a81a5@google.com> Subject: INFO: task hung in __sb_start_write 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"; format=flowed; delsp=yes Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, syzbot found the following crash on: HEAD commit: 06dd3dfeea60 Merge tag 'char-misc-4.17-rc1' of git://git.k... git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=12911087800000 kernel config: https://syzkaller.appspot.com/x/.config?x=301513bac2f9fd9 dashboard link: https://syzkaller.appspot.com/bug?extid=7b2866454055e43c21e5 compiler: gcc (GCC) 8.0.1 20180301 (experimental) Unfortunately, I don't have any reproducer for this crash yet. IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+7b2866454055e43c21e5@syzkaller.appspotmail.com kworker/dying (22) used greatest stack depth: 8440 bytes left INFO: task syz-executor1:4457 blocked for more than 120 seconds. Not tainted 4.16.0+ #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor1 D21448 4457 4449 0x00000000 Call Trace: context_switch kernel/sched/core.c:2848 [inline] __schedule+0x807/0x1e40 kernel/sched/core.c:3490 schedule+0xef/0x430 kernel/sched/core.c:3549 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:269 [inline] rwsem_down_read_failed+0x400/0x6e0 kernel/locking/rwsem-xadd.c:286 call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94 __down_read arch/x86/include/asm/rwsem.h:83 [inline] __percpu_down_read+0x15d/0x200 kernel/locking/percpu-rwsem.c:85 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:49 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] __sb_start_write+0x2d7/0x300 fs/super.c:1340 sb_start_write include/linux/fs.h:1548 [inline] mnt_want_write+0x3f/0xc0 fs/namespace.c:386 do_unlinkat+0x2a3/0xa10 fs/namei.c:4027 SYSC_unlink fs/namei.c:4092 [inline] SyS_unlink+0x26/0x30 fs/namei.c:4090 do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x455027 RSP: 002b:00007ffe9645abc8 EFLAGS: 00000202 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000455027 RDX: 0000000001272983 RSI: 00007ffe9645ac60 RDI: 00007ffe9645ac60 RBP: 00007ffe9645c970 R08: 0000000000000000 R09: 0000000000000010 R10: 000000000000000a R11: 0000000000000202 R12: 0000000001272940 R13: 0000000000000000 R14: 000000000000041b R15: 000000000003297e Showing all locks held in the system: 2 locks held by khungtaskd/878: #0: 00000000e417309b (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 00000000e417309b (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 00000000a42a84b8 (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 2 locks held by rs:main Q:Reg/4288: #0: 00000000658bb541 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1a9/0x1e0 fs/file.c:766 #1: 0000000052aff78e (sb_writers#4){++++}, at: file_start_write include/linux/fs.h:2709 [inline] #1: 0000000052aff78e (sb_writers#4){++++}, at: vfs_write+0x452/0x560 fs/read_write.c:548 2 locks held by getty/4381: #0: 00000000990269ba (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000009f1d2051 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4382: #0: 00000000ecd434e6 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000034d736c1 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4383: #0: 0000000013764982 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000202a6e1f (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4384: #0: 00000000ba3d2e6d (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000e3323037 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4385: #0: 00000000a3add0e7 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000081f7b524 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4386: #0: 00000000a73f06ea (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000002de50dc3 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4387: #0: 0000000087cccc64 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000000a3822a6 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 1 lock held by syz-executor1/4457: #0: 0000000052aff78e (sb_writers#4){++++}, at: sb_start_write include/linux/fs.h:1548 [inline] #0: 0000000052aff78e (sb_writers#4){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:386 1 lock held by syz-executor7/4459: #0: 0000000052aff78e (sb_writers#4){++++}, at: sb_start_write include/linux/fs.h:1548 [inline] #0: 0000000052aff78e (sb_writers#4){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:386 1 lock held by syz-executor5/4460: #0: 0000000052aff78e (sb_writers#4){++++}, at: sb_start_write include/linux/fs.h:1548 [inline] #0: 0000000052aff78e (sb_writers#4){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:386 1 lock held by syz-executor3/4462: #0: 0000000052aff78e (sb_writers#4){++++}, at: sb_start_write include/linux/fs.h:1548 [inline] #0: 0000000052aff78e (sb_writers#4){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:386 2 locks held by syz-executor6/14836: #0: 00000000f86d1ee3 (&mm->mmap_sem){++++}, at: __do_page_fault+0x381/0xe40 arch/x86/mm/fault.c:1328 #1: 0000000002ee4fbd (sb_pagefaults){++++}, at: sb_start_pagefault include/linux/fs.h:1577 [inline] #1: 0000000002ee4fbd (sb_pagefaults){++++}, at: ext4_page_mkwrite+0x1c8/0x1420 fs/ext4/inode.c:6074 1 lock held by syz-executor0/14842: #0: 0000000052aff78e (sb_writers#4){++++}, at: sb_start_write include/linux/fs.h:1548 [inline] #0: 0000000052aff78e (sb_writers#4){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:386 1 lock held by syz-executor4/14843: #0: 0000000052aff78e (sb_writers#4){++++}, at: sb_start_write include/linux/fs.h:1548 [inline] #0: 0000000052aff78e (sb_writers#4){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:386 1 lock held by syz-executor2/14849: #0: 0000000052aff78e (sb_writers#4){++++}, at: sb_start_write include/linux/fs.h:1548 [inline] #0: 0000000052aff78e (sb_writers#4){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:386 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 878 Comm: khungtaskd Not tainted 4.16.0+ #1 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1b9/0x29f lib/dump_stack.c:53 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x151/0x192 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline] check_hung_task kernel/hung_task.c:132 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline] watchdog+0xc10/0xf60 kernel/hung_task.c:249 kthread+0x345/0x410 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 --- This bug is generated by a bot. 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