Message-ID: <66f53709.050a0220.211276.0068.GAE@google.com>
Date: Thu, 26 Sep 2024 03:27:21 -0700
From: syzbot <syzbot+c7aacacf99dcfd3475a7@...kaller.appspotmail.com>
To: bfoster@...hat.com, kent.overstreet@...ux.dev, 
	linux-bcachefs@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [bcachefs?] INFO: task hung in bch2_fs_read_only

Hello,

syzbot found the following issue on:

HEAD commit:    88264981f208 Merge tag 'sched_ext-for-6.12' of git://git.k..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=16f9de9f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=74ffdb3b3fad1a43
dashboard link: https://syzkaller.appspot.com/bug?extid=c7aacacf99dcfd3475a7
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=14b24e07980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17dfb080580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/87eaf0ad6d60/disk-88264981.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/30c01cf8bc82/vmlinux-88264981.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a1407424ea54/bzImage-88264981.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/24e9b0679e2e/mount_0.gz

The issue was bisected to:

commit 359571c327a726d622786aef3833637dacfd5d38
Author: Kent Overstreet <kent.overstreet@...ux.dev>
Date:   Tue Apr 9 04:02:47 2024 +0000

    bcachefs: Fix check_topology() when using node scan

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=11203880580000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=13203880580000
console output: https://syzkaller.appspot.com/x/log.txt?x=15203880580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c7aacacf99dcfd3475a7@...kaller.appspotmail.com
Fixes: 359571c327a7 ("bcachefs: Fix check_topology() when using node scan")

INFO: task syz-executor380:5235 blocked for more than 143 seconds.
      Not tainted 6.11.0-syzkaller-08481-g88264981f208 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor380 state:D stack:23872 pid:5235  tgid:5235  ppid:5232   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5315 [inline]
 __schedule+0x1843/0x4ae0 kernel/sched/core.c:6674
 __schedule_loop kernel/sched/core.c:6751 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6766
 bch2_fs_read_only+0xa86/0x1220 fs/bcachefs/super.c:346
 __bch2_fs_stop+0x105/0x540 fs/bcachefs/super.c:618
 generic_shutdown_super+0x139/0x2d0 fs/super.c:642
 bch2_kill_sb+0x41/0x50 fs/bcachefs/fs.c:2064
 deactivate_locked_super+0xc4/0x130 fs/super.c:473
 cleanup_mnt+0x41f/0x4b0 fs/namespace.c:1373
 task_work_run+0x24f/0x310 kernel/task_work.c:228
 ptrace_notify+0x2d2/0x380 kernel/signal.c:2403
 ptrace_report_syscall include/linux/ptrace.h:415 [inline]
 ptrace_report_syscall_exit include/linux/ptrace.h:477 [inline]
 syscall_exit_work+0xc6/0x190 kernel/entry/common.c:173
 syscall_exit_to_user_mode_prepare kernel/entry/common.c:200 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:205 [inline]
 syscall_exit_to_user_mode+0x279/0x370 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5044059387
RSP: 002b:00007fffa46cc3a8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f5044059387
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fffa46cc460
RBP: 00007fffa46cc460 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000202 R12: 00007fffa46cd4c0
R13: 0000555568abe6c0 R14: 0000000000000001 R15: 431bde82d7b634db
 </TASK>

Showing all locks held in the system:
5 locks held by kworker/u8:0/11:
1 lock held by khungtaskd/30:
 #0: ffffffff8e937ee0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #0: ffffffff8e937ee0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e937ee0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6701
4 locks held by kworker/u8:4/61:
 #0: ffff888012bc9148 ((wq_completion)btree_node_rewrite){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline]
 #0: ffff888012bc9148 ((wq_completion)btree_node_rewrite){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1850 kernel/workqueue.c:3310
 #1: ffffc900015c7d00 ((work_completion)(&a->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline]
 #1: ffffc900015c7d00 ((work_completion)(&a->work)){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1850 kernel/workqueue.c:3310
 #2: ffff8880724042c0 (&c->btree_trans_barrier){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:151 [inline]
 #2: ffff8880724042c0 (&c->btree_trans_barrier){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:250 [inline]
 #2: ffff8880724042c0 (&c->btree_trans_barrier){.+.+}-{0:0}, at: __bch2_trans_get+0x7de/0xd20 fs/bcachefs/btree_iter.c:3200
 #3: ffff888072426690 (&c->gc_lock){.+.+}-{3:3}, at: bch2_btree_update_start+0x682/0x14e0 fs/bcachefs/btree_update_interior.c:1197
2 locks held by getty/4976:
 #0: ffff88803298a0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002f062f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6a6/0x1e00 drivers/tty/n_tty.c:2211
2 locks held by syz-executor380/5235:
 #0: ffff88802e0f20e0 (&type->s_umount_key#44){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff88802e0f20e0 (&type->s_umount_key#44){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff88802e0f20e0 (&type->s_umount_key#44){+.+.}-{3:3}, at: deactivate_super+0xb5/0xf0 fs/super.c:505
 #1: ffff888072400278 (&c->state_lock){+.+.}-{3:3}, at: __bch2_fs_stop+0xfd/0x540 fs/bcachefs/super.c:617

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.11.0-syzkaller-08481-g88264981f208 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
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:223 [inline]
 watchdog+0xff4/0x1040 kernel/hung_task.c:379
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 11 Comm: kworker/u8:0 Not tainted 6.11.0-syzkaller-08481-g88264981f208 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:23 [inline]
RIP: 0010:raw_atomic_read include/linux/atomic/atomic-arch-fallback.h:457 [inline]
RIP: 0010:rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline]
RIP: 0010:rcu_is_watching+0x5a/0xb0 kernel/rcu/tree.c:737
Code: f0 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 f7 e8 ec 56 80 00 48 c7 c3 98 7e 03 00 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38 <84> c0 75 22 8b 03 65 ff 0d 11 3f 89 7e 74 10 83 e0 04 c1 e8 02 5b
RSP: 0018:ffffc90000107618 EFLAGS: 00000802
RAX: 0000000000000000 RBX: ffff8880b8637e98 RCX: ffffffff8142d66f
RDX: 0000000000000000 RSI: ffffffff8c5ffc60 RDI: ffffffff8c5ffc20
RBP: ffffc90000107730 R08: ffffffff901b4b2f R09: 1ffffffff2036965
R10: dffffc0000000000 R11: fffffbfff2036966 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffffff8e2faa50 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000557aa7895600 CR3: 000000000e734000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 trace_tlb_flush+0x3e/0x140 include/trace/events/tlb.h:38
 switch_mm_irqs_off+0x7b0/0xb00
 unuse_temporary_mm arch/x86/kernel/alternative.c:1831 [inline]
 __text_poke+0x8f0/0xd30 arch/x86/kernel/alternative.c:1941
 text_poke arch/x86/kernel/alternative.c:1984 [inline]
 text_poke_bp_batch+0x59c/0xb30 arch/x86/kernel/alternative.c:2317
 text_poke_flush arch/x86/kernel/alternative.c:2486 [inline]
 text_poke_finish+0x30/0x50 arch/x86/kernel/alternative.c:2493
 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146
 static_key_disable_cpuslocked+0xd2/0x1c0 kernel/jump_label.c:240
 static_key_disable+0x1a/0x20 kernel/jump_label.c:248
 toggle_allocation_gate+0x1bf/0x260 mm/kfence/core.c:854
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310
 worker_thread+0x870/0xd30 kernel/workqueue.c:3391
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.548 msecs


---
This report is generated by a bot. It may contain errors.
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection

If the report is already addressed, let syzbot know by replying with:
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#syz test: git://repo/address.git branch-or-commit-hash
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