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    SubjectINFO: task hung in pipe_release (2)
    From
    Hello,

    syzbot found the following issue on:

    HEAD commit: 6ba1b005 Merge tag 'asm-generic-fixes-5.8' of git://git.ke..
    git tree: upstream
    console output: https://syzkaller.appspot.com/x/log.txt?x=16a5a3b0900000
    kernel config: https://syzkaller.appspot.com/x/.config?x=84f076779e989e69
    dashboard link: https://syzkaller.appspot.com/bug?extid=61acc40a49a3e46e25ea
    compiler: gcc (GCC) 10.1.0-syz 20200507
    syz repro: https://syzkaller.appspot.com/x/repro.syz?x=142ae224900000

    IMPORTANT: if you fix the issue, please add the following tag to the commit:
    Reported-by: syzbot+61acc40a49a3e46e25ea@syzkaller.appspotmail.com

    INFO: task syz-executor.0:7075 blocked for more than 143 seconds.
    Not tainted 5.8.0-rc7-syzkaller #0
    "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
    syz-executor.0 D28288 7075 6828 0x00000004
    Call Trace:
    context_switch kernel/sched/core.c:3458 [inline]
    __schedule+0x8ea/0x2210 kernel/sched/core.c:4219
    schedule+0xd0/0x2a0 kernel/sched/core.c:4294
    schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4353
    __mutex_lock_common kernel/locking/mutex.c:1033 [inline]
    __mutex_lock+0x3e2/0x10d0 kernel/locking/mutex.c:1103
    __pipe_lock fs/pipe.c:87 [inline]
    pipe_release+0x49/0x320 fs/pipe.c:722
    __fput+0x33c/0x880 fs/file_table.c:281
    task_work_run+0xdd/0x190 kernel/task_work.c:135
    tracehook_notify_resume include/linux/tracehook.h:188 [inline]
    exit_to_usermode_loop arch/x86/entry/common.c:239 [inline]
    __prepare_exit_to_usermode+0x1e9/0x1f0 arch/x86/entry/common.c:269
    do_syscall_64+0x6c/0xe0 arch/x86/entry/common.c:393
    entry_SYSCALL_64_after_hwframe+0x44/0xa9
    RIP: 0033:0x415ee1
    Code: Bad RIP value.
    RSP: 002b:00007ffd249bc0c0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
    RAX: 0000000000000000 RBX: 0000000000000007 RCX: 0000000000415ee1
    RDX: 0000000000000000 RSI: 00000000007904d0 RDI: 0000000000000006
    RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
    R10: 00007ffd249bc1b0 R11: 0000000000000293 R12: 00000000007905a8
    R13: 00000000000ffc79 R14: ffffffffffffffff R15: 000000000078bfac

    Showing all locks held in the system:
    1 lock held by khungtaskd/1153:
    #0: ffffffff89bc11c0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5779
    1 lock held by in:imklog/6695:
    #0: ffff8880979b6670 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:826
    1 lock held by syz-executor.0/7075:
    #0: ffff8880a8e02068 (&pipe->mutex/1){+.+.}-{3:3}, at: __pipe_lock fs/pipe.c:87 [inline]
    #0: ffff8880a8e02068 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_release+0x49/0x320 fs/pipe.c:722
    2 locks held by syz-executor.0/7077:

    =============================================

    NMI backtrace for cpu 0
    CPU: 0 PID: 1153 Comm: khungtaskd Not tainted 5.8.0-rc7-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+0x18f/0x20d lib/dump_stack.c:118
    nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
    nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62
    trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
    check_hung_uninterruptible_tasks kernel/hung_task.c:209 [inline]
    watchdog+0xd7d/0x1000 kernel/hung_task.c:295
    kthread+0x3b5/0x4a0 kernel/kthread.c:291
    ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293
    Sending NMI from CPU 0 to CPUs 1:
    NMI backtrace for cpu 1
    CPU: 1 PID: 7077 Comm: syz-executor.0 Not tainted 5.8.0-rc7-syzkaller #0
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
    RIP: 0010:iov_iter_alignment+0x39e/0x850 lib/iov_iter.c:1236
    Code: 48 8b 44 24 18 80 38 00 0f 85 f4 03 00 00 4d 8b 7d 18 44 89 e3 48 89 d8 48 c1 e0 04 4c 01 f8 48 8d 78 0c 48 89 fa 48 c1 ea 03 <42> 0f b6 0c 32 48 89 fa 83 e2 07 83 c2 03 38 ca 7c 08 84 c9 0f 85
    RSP: 0018:ffffc9000206f868 EFLAGS: 00000a07
    RAX: ffff8880a8124c00 RBX: 0000000000000000 RCX: ffffffff8395bf6f
    RDX: 1ffff11015024981 RSI: ffffffff8395be14 RDI: ffff8880a8124c0c
    RBP: 0000000000000000 R08: 0000000000000000 R09: ffff8880994e63c7
    R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
    R13: ffffc9000206fc68 R14: dffffc0000000000 R15: ffff8880a8124c00
    FS: 00007fba306d0700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
    CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 00007f9573761000 CR3: 0000000091a0d000 CR4: 00000000001406e0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    Call Trace:
    ext4_unaligned_io fs/ext4/file.c:175 [inline]
    ext4_dio_write_iter fs/ext4/file.c:465 [inline]
    ext4_file_write_iter+0x345/0x13d0 fs/ext4/file.c:653
    call_write_iter include/linux/fs.h:1908 [inline]
    do_iter_readv_writev+0x567/0x780 fs/read_write.c:713
    do_iter_write+0x188/0x5f0 fs/read_write.c:1018
    vfs_iter_write+0x70/0xa0 fs/read_write.c:1059
    iter_file_splice_write+0x721/0xbe0 fs/splice.c:750
    do_splice_from fs/splice.c:846 [inline]
    do_splice+0xbcd/0x1820 fs/splice.c:1144
    __do_sys_splice fs/splice.c:1419 [inline]
    __se_sys_splice fs/splice.c:1401 [inline]
    __x64_sys_splice+0x198/0x250 fs/splice.c:1401
    do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
    entry_SYSCALL_64_after_hwframe+0x44/0xa9
    RIP: 0033:0x45c369
    Code: 8d b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 5b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
    RSP: 002b:00007fba306cfc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
    RAX: ffffffffffffffda RBX: 0000000000032240 RCX: 000000000045c369
    RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000005
    RBP: 000000000078bff8 R08: 000000000000ffe0 R09: 0000000000000000
    R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bfac
    R13: 00007ffd249bc04f R14: 00007fba306d09c0 R15: 000000000078bfac


    ---
    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

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