syzbot

INFO: task udevd:349 blocked for more than 122 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd           state:D stack:0     pid:349   tgid:349   ppid:110    flags:0x00000000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5996 [inline]
 __schedule+0x134f/0x1ea0 kernel/sched/core.c:7843
 __schedule_loop kernel/sched/core.c:7924 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7939
 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:7996
 __mutex_lock_common kernel/locking/mutex.c:707 [inline]
 __mutex_lock+0x960/0x1bb0 kernel/locking/mutex.c:803
 __mutex_lock_slowpath+0xe/0x20 kernel/locking/mutex.c:1134
 mutex_lock+0x113/0x1d0 kernel/locking/mutex.c:285
 bdev_open+0xd5/0xd60 block/bdev.c:926
 blkdev_open+0x3d1/0x560 block/fops.c:627
 do_dentry_open+0x97b/0x1510 fs/open.c:960
 vfs_open+0x86/0x240 fs/open.c:1092
 do_open fs/namei.c:3782 [inline]
 path_openat+0x2bb1/0x34f0 fs/namei.c:3941
 do_filp_open+0x1f5/0x440 fs/namei.c:3968
 do_sys_openat2+0x134/0x1d0 fs/open.c:1440
 do_sys_open fs/open.c:1455 [inline]
 __do_sys_openat fs/open.c:1471 [inline]
 __se_sys_openat fs/open.c:1466 [inline]
 __x64_sys_openat+0x13a/0x170 fs/open.c:1466
 x64_sys_call+0xe69/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fe8fbdca407
RSP: 002b:00007ffda210ad00 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fe8fbd3e880 RCX: 00007fe8fbdca407
RDX: 00000000000a0800 RSI: 00005648f3961700 RDI: ffffffffffffff9c
RBP: 00005648f395e2c0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00005648f3b93a80
R13: 00005648f3b9f0f0 R14: 0000000000000000 R15: 00005648f3b93a80
 </TASK>
INFO: task syz.3.3709:11369 blocked for more than 123 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.3709      state:D stack:0     pid:11369 tgid:11368 ppid:6959   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5996 [inline]
 __schedule+0x134f/0x1ea0 kernel/sched/core.c:7843
 __schedule_loop kernel/sched/core.c:7924 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7939
 io_schedule+0x88/0xe0 kernel/sched/core.c:8753
 folio_wait_bit_common+0x6d8/0x950 mm/filemap.c:1355
 folio_put_wait_locked mm/filemap.c:1519 [inline]
 do_read_cache_folio+0x14d/0x4c0 mm/filemap.c:4042
 read_cache_folio+0x54/0x90 mm/filemap.c:4092
 read_mapping_folio include/linux/pagemap.h:1021 [inline]
 read_part_sector+0xcc/0x250 block/partitions/core.c:716
 msdos_partition+0x116/0x2fd0 block/partitions/msdos.c:592
 check_partition block/partitions/core.c:138 [inline]
 blk_add_partitions block/partitions/core.c:583 [inline]
 bdev_disk_changed+0x825/0x1610 block/partitions/core.c:687
 loop_reread_partitions+0x64/0x110 drivers/block/loop.c:467
 loop_configure+0x1068/0x13a0 drivers/block/loop.c:1078
 lo_ioctl+0xa8b/0x2070 drivers/block/loop.c:1520
 blkdev_ioctl+0x54b/0x690 block/ioctl.c:699
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0x135/0x1b0 fs/ioctl.c:893
 __x64_sys_ioctl+0x7f/0xa0 fs/ioctl.c:893
 x64_sys_call+0x1878/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7ff1bf99c629
RSP: 002b:00007ff1c085c028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ff1bfc15fa0 RCX: 00007ff1bf99c629
RDX: 0000200000000280 RSI: 0000000000004c0a RDI: 0000000000000003
RBP: 00007ff1bfa32b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff1bfc16038 R14: 00007ff1bfc15fa0 R15: 00007ffcd8263c78
 </TASK>
INFO: task syz.0.3859:11796 blocked for more than 124 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.3859      state:D stack:0     pid:11796 tgid:11795 ppid:6168   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5996 [inline]
 __schedule+0x134f/0x1ea0 kernel/sched/core.c:7843
 __schedule_loop kernel/sched/core.c:7924 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7939
 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:7996
 __mutex_lock_common kernel/locking/mutex.c:707 [inline]
 __mutex_lock+0x960/0x1bb0 kernel/locking/mutex.c:803
 __mutex_lock_slowpath+0xe/0x20 kernel/locking/mutex.c:1134
 mutex_lock+0x113/0x1d0 kernel/locking/mutex.c:285
 sync_bdevs+0x1af/0x350 block/bdev.c:1269
 ksys_sync+0xc6/0x170 fs/sync.c:106
 __ia32_sys_sync+0x12/0x20 fs/sync.c:114
 x64_sys_call+0x2a58/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:163
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fef6379c629
RSP: 002b:00007fef621f7028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fef63a15fa0 RCX: 00007fef6379c629
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fef63a15fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fef63a16038 R14: 00007fef63a15fa0 R15: 00007fff2ada2148
 </TASK>
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 73dd41fee924560e78783f72ff837ca22365b77d
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0x140/0x1c0 lib/dump_stack.c:120
 dump_stack+0x19/0x20 lib/dump_stack.c:129
 nmi_cpu_backtrace+0x2ba/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x142/0x2c0 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:41
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:267 [inline]
 watchdog+0xdad/0xf00 kernel/hung_task.c:423
 kthread+0x2c9/0x370 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 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
CPU: 1 UID: 0 PID: 14825 Comm: syz.1.4841 Not tainted syzkaller #0 73dd41fee924560e78783f72ff837ca22365b77d
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:arch_stack_walk+0x13f/0x170 arch/x86/kernel/stacktrace.c:24
Code: 4d 89 f3 41 ba 3a c7 f0 cd 45 03 53 f1 74 02 0f 0b 2e e8 88 e0 c1 1e 84 c0 74 11 4c 89 ff e8 d8 96 06 00 83 bd 78 ff ff ff 00 <75> c1 65 48 8b 04 25 28 00 00 00 48 3b 45 d8 75 12 48 83 c4 68 5b
RSP: 0018:ffffc900027a6da8 EFLAGS: 00000002
RAX: 00000000027a6d01 RBX: ffffc900027a6e60 RCX: 00000000027a6d01
RDX: ffffc900027a7f48 RSI: 1ffff920004f4db6 RDI: ffffc900027a6e00
RBP: ffffc900027a6e30 R08: ffffc900027a6e70 R09: ffffc900027a6e68
R10: 0000000000000010 R11: ffffffff8175cbd0 R12: ffff888114c35f00
R13: 0000000000000001 R14: ffffffff8175cbd0 R15: ffffc900027a6da8
FS:  00007f67d51e76c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555656e74e8 CR3: 0000000127592000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:49
 __kasan_record_aux_stack+0xb2/0xd0 mm/kasan/generic.c:541
 kasan_record_aux_stack_noalloc+0xf/0x20 mm/kasan/generic.c:551
 irq_work_queue_on+0xea/0x210 kernel/irq_work.c:150
 tell_cpu_to_push+0x5bc/0x660 kernel/sched/rt.c:2423
 pull_rt_task kernel/sched/rt.c:2489 [inline]
 balance_rt+0x2a0/0x440 kernel/sched/rt.c:1741
 prev_balance kernel/sched/core.c:6628 [inline]
 __pick_next_task kernel/sched/core.c:6670 [inline]
 pick_next_task kernel/sched/core.c:7176 [inline]
 __schedule+0x964/0x1ea0 kernel/sched/core.c:7769
 __schedule_loop kernel/sched/core.c:7924 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7939
 schedule_timeout+0xc7/0x3b0 kernel/time/timer.c:2596
 unix_wait_for_peer+0x1f6/0x300 net/unix/af_unix.c:1540
 unix_dgram_sendmsg+0x1173/0x1ac0 net/unix/af_unix.c:2142
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0xa8c/0xae0 net/socket.c:2610
 ___sys_sendmsg+0x2a6/0x370 net/socket.c:2664
 __sys_sendmmsg+0x2b4/0x4e0 net/socket.c:2750
 __do_sys_sendmmsg net/socket.c:2779 [inline]
 __se_sys_sendmmsg net/socket.c:2776 [inline]
 __x64_sys_sendmmsg+0xa4/0xc0 net/socket.c:2776
 x64_sys_call+0xfec/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:308
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f67d439c629
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f67d51e7028 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f67d4615fa0 RCX: 00007f67d439c629
RDX: 0000000000000651 RSI: 0000200000000000 RDI: 0000000000000007
RBP: 00007f67d4432b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f67d4616038 R14: 00007f67d4615fa0 R15: 00007ffdcdaa26d8
 </TASK>