Message-Id: <419ADDD0-A731-45E5-9B51-DCB2B0CA1717@gmail.com>
Date: Tue, 5 Aug 2025 19:12:02 +0800
From: Alan Huang <mmpgouride@...il.com>
To: syzbot <syzbot+23e4a7772eb9a9715b85@...kaller.appspotmail.com>
Cc: bfoster@...hat.com,
 kent.overstreet@...ux.dev,
 linux-bcachefs@...r.kernel.org,
 linux-kernel@...r.kernel.org,
 syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bcachefs?] INFO: task hung in pipe_release (6)

On Feb 28, 2025, at 03:55, syzbot <syzbot+23e4a7772eb9a9715b85@...kaller.appspotmail.com> wrote:
> 
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    d082ecbc71e9 Linux 6.14-rc4
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11fe26e4580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=8de9cc84d5960254
> dashboard link: https://syzkaller.appspot.com/bug?extid=23e4a7772eb9a9715b85
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15fe26e4580000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/5efd609bee65/disk-d082ecbc.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/dfadbc41acd8/vmlinux-d082ecbc.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/50189caf8ad6/bzImage-d082ecbc.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/470a5d56ad27/mount_0.gz
> 
> The issue was bisected to:
> 
> commit 1d16c605cc55ef26f0c65b362665a6c99080ccbc
> Author: Kent Overstreet <kent.overstreet@...ux.dev>
> Date:   Thu Nov 9 19:22:46 2023 +0000
> 
>    bcachefs: Disk space accounting rewrite
> 
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=117c9db0580000
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=137c9db0580000
> console output: https://syzkaller.appspot.com/x/log.txt?x=157c9db0580000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+23e4a7772eb9a9715b85@...kaller.appspotmail.com
> Fixes: 1d16c605cc55 ("bcachefs: Disk space accounting rewrite")
> 
> INFO: task syz-executor:5849 blocked for more than 143 seconds.
>      Not tainted 6.14.0-rc4-syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:syz-executor    state:D stack:20592 pid:5849  tgid:5849  ppid:5843   task_flags:0x400100 flags:0x00000002
> Call Trace:
> <TASK>
> context_switch kernel/sched/core.c:5378 [inline]
> __schedule+0x18bc/0x4c40 kernel/sched/core.c:6765
> __schedule_loop kernel/sched/core.c:6842 [inline]
> schedule+0x14b/0x320 kernel/sched/core.c:6857
> schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6914
> __mutex_lock_common kernel/locking/mutex.c:662 [inline]
> __mutex_lock+0x817/0x1010 kernel/locking/mutex.c:730
> pipe_release+0x48/0x320 fs/pipe.c:728
> __fput+0x3e9/0x9f0 fs/file_table.c:464
> __do_sys_close fs/open.c:1580 [inline]
> __se_sys_close fs/open.c:1565 [inline]
> __x64_sys_close+0x7f/0x110 fs/open.c:1565
> do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7fe6de58bda0
> RSP: 002b:00007fff16f18de8 EFLAGS: 00000202 ORIG_RAX: 0000000000000003
> RAX: ffffffffffffffda RBX: 0000555580184ec0 RCX: 00007fe6de58bda0
> RDX: 0000000000000000 RSI: 0000000000000004 RDI: 000000000000001d
> RBP: 00005555801847a0 R08: 0000000000000001 R09: 0000000000000000
> R10: 0000000000000008 R11: 0000000000000202 R12: 00007fff16f18e10
> R13: 0000000000000023 R14: 0000555580184f0c R15: 00005555801854c8
> </TASK>
> INFO: task syz.3.64:6573 blocked for more than 143 seconds.
>      Not tainted 6.14.0-rc4-syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:syz.3.64        state:D stack:10240 pid:6573  tgid:6572  ppid:5971   task_flags:0x400140 flags:0x00004004
> Call Trace:
> <TASK>
> context_switch kernel/sched/core.c:5378 [inline]
> __schedule+0x18bc/0x4c40 kernel/sched/core.c:6765
> __schedule_loop kernel/sched/core.c:6842 [inline]
> schedule+0x14b/0x320 kernel/sched/core.c:6857
> io_schedule+0x8d/0x110 kernel/sched/core.c:7690
> folio_wait_bit_common+0x839/0xee0 mm/filemap.c:1318
> folio_lock include/linux/pagemap.h:1163 [inline]
> invalidate_inode_pages2_range+0x48f/0x960 mm/truncate.c:639
> bch2_write_invalidate_inode_pages_range+0xce/0x120 fs/bcachefs/fs-io-pagecache.c:68
> bch2_direct_write+0x2ebf/0x3190 fs/bcachefs/fs-io-direct.c:653
> bch2_write_iter+0x19d/0x2cd0 fs/bcachefs/fs-io-buffered.c:1047
> iter_file_splice_write+0xbfa/0x1510 fs/splice.c:743
> do_splice_from fs/splice.c:941 [inline]
> direct_splice_actor+0x11b/0x220 fs/splice.c:1164
> splice_direct_to_actor+0x586/0xc80 fs/splice.c:1108
> do_splice_direct_actor fs/splice.c:1207 [inline]
> do_splice_direct+0x289/0x3e0 fs/splice.c:1233
> do_sendfile+0x564/0x8a0 fs/read_write.c:1363
> __do_sys_sendfile64 fs/read_write.c:1424 [inline]
> __se_sys_sendfile64+0x17c/0x1e0 fs/read_write.c:1410
> do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f893338d169
> RSP: 002b:00007f89342ae038 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
> RAX: ffffffffffffffda RBX: 00007f89335a5fa0 RCX: 00007f893338d169
> RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000006
> RBP: 00007f893340e2a0 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000fffa83 R11: 0000000000000246 R12: 0000000000000000
> R13: 0000000000000000 R14: 00007f89335a5fa0 R15: 00007fffa972dc48
> </TASK>
> INFO: task syz.3.64:6613 blocked for more than 144 seconds.
>      Not tainted 6.14.0-rc4-syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:syz.3.64        state:D stack:15824 pid:6613  tgid:6572  ppid:5971   task_flags:0x440140 flags:0x00004004
> Call Trace:
> <TASK>
> context_switch kernel/sched/core.c:5378 [inline]
> __schedule+0x18bc/0x4c40 kernel/sched/core.c:6765
> __schedule_loop kernel/sched/core.c:6842 [inline]
> schedule+0x14b/0x320 kernel/sched/core.c:6857
> __bch2_two_state_lock+0x229/0x2c0 fs/bcachefs/two_state_shared_lock.c:7
> bch2_two_state_lock fs/bcachefs/two_state_shared_lock.h:55 [inline]
> bch2_readahead+0x9e1/0x1240 fs/bcachefs/fs-io-buffered.c:272
> read_pages+0x179/0x570 mm/readahead.c:161
> page_cache_ra_unbounded+0x708/0x820 mm/readahead.c:298
> filemap_readahead mm/filemap.c:2549 [inline]
> filemap_get_pages+0x9e4/0x1fb0 mm/filemap.c:2594
> filemap_splice_read+0x68e/0xef0 mm/filemap.c:2971
> do_splice_read fs/splice.c:985 [inline]
> splice_file_to_pipe+0x290/0x500 fs/splice.c:1295
> do_sendfile+0x508/0x8a0 fs/read_write.c:1369
> __do_sys_sendfile64 fs/read_write.c:1424 [inline]
> __se_sys_sendfile64+0x17c/0x1e0 fs/read_write.c:1410
> do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f893338d169
> RSP: 002b:00007f893428d038 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
> RAX: ffffffffffffffda RBX: 00007f89335a6080 RCX: 00007f893338d169
> RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000000
> RBP: 00007f893340e2a0 R08: 0000000000000000 R09: 0000000000000000
> R10: 00000000000002ab R11: 0000000000000246 R12: 0000000000000000
> R13: 0000000000000000 R14: 00007f89335a6080 R15: 00007fffa972dc48
> </TASK>
> 
> Showing all locks held in the system:
> 1 lock held by khungtaskd/30:
> #0: ffffffff8eb38f60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
> #0: ffffffff8eb38f60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
> #0: ffffffff8eb38f60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6746
> 2 locks held by getty/5582:
> #0: ffff88803571a0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
> #1: ffffc90002fde2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x616/0x1770 drivers/tty/n_tty.c:2211
> 1 lock held by syz-executor/5849:
> #0: ffff88802a3d6068 (&pipe->mutex){+.+.}-{4:4}, at: pipe_release+0x48/0x320 fs/pipe.c:728
> 4 locks held by kworker/u8:4/6005:
> #0: ffff8880b873e7d8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:598
> #1: ffff8880b8728948 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x41d/0x7a0 kernel/sched/psi.c:987
> #2: ffff8880b872a398 (&base->lock){-.-.}-{2:2}, at: lock_timer_base kernel/time/timer.c:1046 [inline]
> #2: ffff8880b872a398 (&base->lock){-.-.}-{2:2}, at: __mod_timer+0x24a/0x10e0 kernel/time/timer.c:1127
> #3: ffffffff9a832208 (&obj_hash[i].lock){-.-.}-{2:2}, at: debug_object_activate+0x17f/0x580 lib/debugobjects.c:818
> 1 lock held by syz.3.64/6573:
> #0: ffff8880741e2420 (sb_writers#13){.+.+}-{0:0}, at: direct_splice_actor+0x49/0x220 fs/splice.c:1163
> 2 locks held by syz.3.64/6613:
> #0: ffff88802a3d6068 (&pipe->mutex){+.+.}-{4:4}, at: splice_file_to_pipe+0x2e/0x500 fs/splice.c:1292
> #1: ffff8880744ba148 (mapping.invalidate_lock#3){.+.+}-{4:4}, at: filemap_invalidate_lock_shared include/linux/fs.h:932 [inline]
> #1: ffff8880744ba148 (mapping.invalidate_lock#3){.+.+}-{4:4}, at: page_cache_ra_unbounded+0x156/0x820 mm/readahead.c:229
> 
> =============================================
> 
> NMI backtrace for cpu 0
> CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.14.0-rc4-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
> Call Trace:
> <TASK>
> __dump_stack lib/dump_stack.c:94 [inline]
> dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
> nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113
> nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
> trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
> check_hung_uninterruptible_tasks kernel/hung_task.c:236 [inline]
> watchdog+0x1058/0x10a0 kernel/hung_task.c:399
> kthread+0x7a9/0x920 kernel/kthread.c:464
> ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
> </TASK>
> Sending NMI from CPU 0 to CPUs 1:
> NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
> NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:106 [inline]
> NMI backtrace for cpu 1 skipped: idling at acpi_safe_halt+0x21/0x30 drivers/acpi/processor_idle.c:111
> 
> 
> ---
> 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@...glegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
> 
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
> 
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
> 
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
> 
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
> 
> If you want to undo deduplication, reply with:
> #syz undup
> 

#syz test: https://github.com/alanskind/bcachefs 5f63c1c6b909eb3c306a336b72f6fe09f37e11ab

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