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SubjectRe: INFO: task hung in __generic_file_fsync (2)
On Wed, Jan 01, 2020 at 12:45:11PM -0800, syzbot wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: bf8d1cd4 Merge tag 'scsi-fixes' of git://git.kernel.org/pu..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11b80869e00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=ed9d672709340e35
> dashboard link: https://syzkaller.appspot.com/bug?extid=44c32606d8669fb0d45c
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=137e2615e00000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11306971e00000
>
> The bug was bisected to:
>
> commit 6dc4f100c175dd0511ae8674786e7c9006cdfbfa
> Author: Ming Lei <ming.lei@redhat.com>
> Date: Fri Feb 15 11:13:19 2019 +0000
>
> block: allow bio_for_each_segment_all() to iterate over multi-page bvec
>
> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=130c5e49e00000
> final crash: https://syzkaller.appspot.com/x/report.txt?x=108c5e49e00000
> console output: https://syzkaller.appspot.com/x/log.txt?x=170c5e49e00000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+44c32606d8669fb0d45c@syzkaller.appspotmail.com
> Fixes: 6dc4f100c175 ("block: allow bio_for_each_segment_all() to iterate
> over multi-page bvec")
>
> INFO: task syz-executor072:10629 blocked for more than 143 seconds.
> Not tainted 5.5.0-rc3-syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> syz-executor072 D25264 10629 10066 0x00004004
> Call Trace:
> context_switch kernel/sched/core.c:3385 [inline]
> __schedule+0x934/0x1f90 kernel/sched/core.c:4081
> schedule+0xdc/0x2b0 kernel/sched/core.c:4155
> io_schedule+0x1c/0x70 kernel/sched/core.c:5799
> wait_on_page_bit_common mm/filemap.c:1175 [inline]
> wait_on_page_bit+0x27c/0xa60 mm/filemap.c:1224
> wait_on_page_writeback+0x1b2/0x4f0 mm/page-writeback.c:2822
> __filemap_fdatawait_range+0x145/0x340 mm/filemap.c:526
> file_write_and_wait_range+0x1ac/0x210 mm/filemap.c:786
> __generic_file_fsync+0x79/0x200 fs/libfs.c:1000
> fat_file_fsync+0x78/0x210 fs/fat/file.c:190
> vfs_fsync_range+0x141/0x230 fs/sync.c:197
> generic_write_sync include/linux/fs.h:2856 [inline]
> generic_file_write_iter+0x4ea/0x68e mm/filemap.c:3474
> call_write_iter include/linux/fs.h:1902 [inline]
> do_iter_readv_writev+0x5f8/0x8f0 fs/read_write.c:693
> do_iter_write fs/read_write.c:970 [inline]
> do_iter_write+0x184/0x610 fs/read_write.c:951
> vfs_iter_write+0x77/0xb0 fs/read_write.c:983
> iter_file_splice_write+0x717/0xc10 fs/splice.c:760
> do_splice_from fs/splice.c:863 [inline]
> direct_splice_actor+0x123/0x190 fs/splice.c:1037
> splice_direct_to_actor+0x3b4/0xa30 fs/splice.c:992
> do_splice_direct+0x1da/0x2a0 fs/splice.c:1080
> do_sendfile+0x597/0xd00 fs/read_write.c:1464
> __do_sys_sendfile64 fs/read_write.c:1525 [inline]
> __se_sys_sendfile64 fs/read_write.c:1511 [inline]
> __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1511
> do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x445e59
> Code: Bad RIP value.
> RSP: 002b:00007ffc4bfab018 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000445e59
> RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000004
> RBP: 0000000000000000 R08: 0000000000402fe0 R09: 0000000000402fe0
> R10: 00008080fffffffe R11: 0000000000000246 R12: 0000000000000082
> R13: 0000000000402fe0 R14: 0000000000000000 R15: 0000000000000000
>
> Showing all locks held in the system:
> 1 lock held by khungtaskd/1116:
> #0: ffffffff899a5680 (rcu_read_lock){....}, at:
> debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5334
> 1 lock held by rs:main Q:Reg/9913:
> #0: ffff8880ae937358 (&rq->lock){-.-.}, at: newidle_balance+0xa28/0xe80
> kernel/sched/fair.c:10177
> 1 lock held by rsyslogd/9915:
> #0: ffff888087f713e0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110
> fs/file.c:801
> 2 locks held by getty/10037:
> #0: ffff8880a2d26090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40
> drivers/tty/tty_ldsem.c:340
> #1: ffffc900018132e0 (&ldata->atomic_read_lock){+.+.}, at:
> n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
> 2 locks held by getty/10038:
> #0: ffff88809f419090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40
> drivers/tty/tty_ldsem.c:340
> #1: ffffc900018932e0 (&ldata->atomic_read_lock){+.+.}, at:
> n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
> 2 locks held by getty/10039:
> #0: ffff8880a2725090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40
> drivers/tty/tty_ldsem.c:340
> #1: ffffc900018732e0 (&ldata->atomic_read_lock){+.+.}, at:
> n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
> 2 locks held by getty/10040:
> #0: ffff8880966a2090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40
> drivers/tty/tty_ldsem.c:340
> #1: ffffc900018832e0 (&ldata->atomic_read_lock){+.+.}, at:
> n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
> 2 locks held by getty/10041:
> #0: ffff88809e168090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40
> drivers/tty/tty_ldsem.c:340
> #1: ffffc900017f32e0 (&ldata->atomic_read_lock){+.+.}, at:
> n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
> 2 locks held by getty/10042:
> #0: ffff8880a7c45090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40
> drivers/tty/tty_ldsem.c:340
> #1: ffffc900018332e0 (&ldata->atomic_read_lock){+.+.}, at:
> n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
> 2 locks held by getty/10043:
> #0: ffff88809958e090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40
> drivers/tty/tty_ldsem.c:340
> #1: ffffc900011402e0 (&ldata->atomic_read_lock){+.+.}, at:
> n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
> 1 lock held by syz-executor072/10629:
> #0: ffff88809a52a428 (sb_writers#9){.+.+}, at: file_start_write
> include/linux/fs.h:2885 [inline]
> #0: ffff88809a52a428 (sb_writers#9){.+.+}, at: do_sendfile+0x9b9/0xd00
> fs/read_write.c:1463
>
> =============================================
>
> NMI backtrace for cpu 0
> CPU: 0 PID: 1116 Comm: khungtaskd Not tainted 5.5.0-rc3-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0x197/0x210 lib/dump_stack.c:118
> nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101
> nmi_trigger_cpumask_backtrace+0x23b/0x28b 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:146 [inline]
> check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline]
> watchdog+0xb11/0x10c0 kernel/hung_task.c:289
> kthread+0x361/0x430 kernel/kthread.c:255
> ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
> Sending NMI from CPU 0 to CPUs 1:
> NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0xe/0x10
> arch/x86/include/asm/irqflags.h:60
>

It has been addressed by:

https://lore.kernel.org/linux-block/bcc25948-7250-7c82-a764-91ce4c938185@kernel.dk/T/#t

Thanks,
Ming

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