Hello, syzbot found the following issue on:
HEAD commit: 4a0c9b339199 Merge tag 'probes-fixes-v6.18-rc4' of git://g.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=12323812580000 kernel config: https://syzkaller.appspot.com/x/.config?x=e46b8a1c645465a9 dashboard link: https://syzkaller.appspot.com/bug?extid=774863666ef5b025c9d0 compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/2d880d82a810/disk-4a0c9b33.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/75307faea32a/vmlinux-4a0c9b33.xz kernel image: https://storage.googleapis.com/syzbot-assets/9d3f4c38a2eb/bzImage-4a0c9b33.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: [email protected] INFO: task syz.6.3379:19656 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.6.3379 state:D stack:28776 pid:19656 tgid:19654 ppid:16553 task_flags:0x400040 flags:0x00080002 Call Trace: <TASK> context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929 __schedule_loop kernel/sched/core.c:7011 [inline] schedule+0x165/0x360 kernel/sched/core.c:7026 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7083 __mutex_lock_common kernel/locking/mutex.c:676 [inline] __mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:760 blk_trace_startstop+0xa3/0x640 kernel/trace/blktrace.c:682 blk_trace_ioctl+0x19b/0x430 kernel/trace/blktrace.c:724 blkdev_common_ioctl+0xdf4/0x2550 block/ioctl.c:630 blkdev_ioctl+0x4f6/0x6d0 block/ioctl.c:699 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fbcfcb8f6c9 RSP: 002b:00007fbcfdaa3038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fbcfcde6090 RCX: 00007fbcfcb8f6c9 RDX: 0000000000000000 RSI: 0000000000001275 RDI: 0000000000000003 RBP: 00007fbcfcc11f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fbcfcde6128 R14: 00007fbcfcde6090 R15: 00007fbcfcf0fa28 </TASK> Showing all locks held in the system: 1 lock held by khungtaskd/31: #0: ffffffff8df3d660 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8df3d660 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #0: ffffffff8df3d660 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775 2 locks held by getty/5588: #0: ffff888032fa10a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222 3 locks held by syz.6.3379/19655: 1 lock held by syz.6.3379/19656: #0: ffff888142f2b068 (&q->debugfs_mutex){+.+.}-{4:4}, at: blk_trace_startstop+0xa3/0x640 kernel/trace/blktrace.c:682 ============================================= NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Call Trace: <TASK> dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:332 [inline] watchdog+0xf60/0xfa0 kernel/hung_task.c:495 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK> Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 19655 Comm: syz.6.3379 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 RIP: 0010:unwind_get_return_address+0x4d/0x90 arch/x86/kernel/unwind_orc.c:369 Code: c0 75 4c 83 3b 00 74 3a 48 83 c3 48 49 89 df 49 c1 ef 03 43 80 3c 37 00 74 08 48 89 df e8 4b 30 b2 00 48 8b 3b e8 b3 cf 18 00 <85> c0 74 14 43 80 3c 37 00 74 08 48 89 df e8 30 30 b2 00 48 8b 03 RSP: 0018:ffffc9000b257668 EFLAGS: 00000202 RAX: 0000000000000001 RBX: ffffc9000b2576d0 RCX: 6861806b914a4f00 RDX: 0000000000000001 RSI: ffffffff8d8f46a3 RDI: ffffffff846da7ad RBP: ffffc9000b257710 R08: ffffc9000b257dd0 R09: 0000000000000000 R10: ffffc9000b2576d8 R11: fffff5200164aedd R12: ffff888066a03c80 R13: 1ffff9200164aefc R14: dffffc0000000000 R15: 1ffff9200164aeda FS: 00007fbcfdac46c0(0000) GS:ffff88812623b000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f184bdb3ad8 CR3: 0000000043d28000 CR4: 00000000003526f0 Call Trace: <TASK> arch_stack_walk+0xfc/0x150 arch/x86/kernel/stacktrace.c:26 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 save_stack+0xf5/0x1f0 mm/page_owner.c:156 __reset_page_owner+0x71/0x1f0 mm/page_owner.c:311 reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1394 [inline] __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2906 relay_destroy_buf+0x10e/0x3a0 kernel/relay.c:200 relay_remove_buf kernel/relay.c:220 [inline] kref_put include/linux/kref.h:65 [inline] relay_close_buf kernel/relay.c:435 [inline] relay_open+0x734/0x920 kernel/relay.c:531 do_blk_trace_setup+0x561/0x980 kernel/trace/blktrace.c:572 blk_trace_setup+0x116/0x1f0 kernel/trace/blktrace.c:614 blk_trace_ioctl+0x181/0x430 kernel/trace/blktrace.c:712 blkdev_ioctl+0x41d/0x6d0 block/ioctl.c:694 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fbcfcb8f6c9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fbcfdac4038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fbcfcde5fa0 RCX: 00007fbcfcb8f6c9 RDX: 00002000000000c0 RSI: 00000000c0481273 RDI: 0000000000000003 RBP: 00007fbcfcc11f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fbcfcde6038 R14: 00007fbcfcde5fa0 R15: 00007fbcfcf0fa28 </TASK> --- 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 [email protected]. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title 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
