[syzbot] [arm?] BUG: using __this_cpu_read() in preemptible code in __delay

Thu Feb 26 07:05:25 PST 2026

Hello,

syzbot found the following issue on:

HEAD commit:    32a92f8c8932 Convert more 'alloc_obj' cases to default GFP..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1019fc02580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b77d736d2f4fe1b1
dashboard link: https://syzkaller.appspot.com/bug?extid=b29d18a34746f34c94cc
compiler:       aarch64-linux-gnu-gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/fa3fbcfdac58/non_bootable_disk-32a92f8c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/aabf4d7d9d6a/vmlinux-32a92f8c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0367e274b699/Image-32a92f8c.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b29d18a34746f34c94cc at syzkaller.appspotmail.com

BUG: using __this_cpu_read() in preemptible [00000000] code: syz.0.1012/5537
caller is __this_cpu_preempt_check+0x20/0x40 lib/smp_processor_id.c:64
CPU: 0 UID: 0 PID: 5537 Comm: syz.0.1012 Tainted: G             L      syzkaller #0 PREEMPT 
Tainted: [L]=SOFTLOCKUP
Hardware name: linux,dummy-virt (DT)
Call trace:
 show_stack+0x18/0x24 arch/arm64/kernel/stacktrace.c:499 (C)
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x7c/0xb0 lib/dump_stack.c:120
 dump_stack+0x1c/0x28 lib/dump_stack.c:129
 check_preemption_disabled+0xe0/0xe8 lib/smp_processor_id.c:47
 __this_cpu_preempt_check+0x20/0x40 lib/smp_processor_id.c:64
 __arch_counter_get_cntvct_stable arch/arm64/include/asm/arch_timer.h:195 [inline]
 __delay+0x40/0x374 arch/arm64/lib/delay.c:39
 __const_udelay+0x48/0x64 arch/arm64/lib/delay.c:66
 udelay include/asm-generic/delay.h:62 [inline]
 snd_timer_close_locked+0x258/0x94c sound/core/timer.c:443
 snd_timer_close+0xa4/0x120 sound/core/timer.c:476
 snd_seq_timer_close+0x88/0xd0 sound/core/seq/seq_timer.c:311
 queue_delete+0x50/0xac sound/core/seq/seq_queue.c:126
 snd_seq_queue_delete+0x2c/0x58 sound/core/seq/seq_queue.c:188
 snd_seq_ioctl_delete_queue+0x6c/0xa0 sound/core/seq/seq_clientmgr.c:1546
 call_seq_client_ctl+0x94/0x120 sound/core/seq/seq_clientmgr.c:2419
 snd_seq_kernel_client_ctl+0x68/0x100 sound/core/seq/seq_clientmgr.c:2447
 delete_seq_queue.isra.0+0xbc/0x124 sound/core/seq/oss/seq_oss_init.c:371
 snd_seq_oss_release+0x13c/0x1a0 sound/core/seq/oss/seq_oss_init.c:416
 odev_release+0x4c/0x88 sound/core/seq/oss/seq_oss.c:141
 __fput+0x2d0/0x958 fs/file_table.c:469
 ____fput+0x14/0x20 fs/file_table.c:497
 task_work_run+0x134/0x238 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0x194/0x1c8 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 exit_to_user_mode_prepare_legacy include/linux/irq-entry-common.h:242 [inline]
 arm64_exit_to_user_mode arch/arm64/kernel/entry-common.c:81 [inline]
 el0_svc+0x258/0x29c arch/arm64/kernel/entry-common.c:725
 el0t_64_sync_handler+0xa0/0xe4 arch/arm64/kernel/entry-common.c:743
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596
BUG: using __this_cpu_read() in preemptible [00000000] code: syz.0.1012/5537
caller is __this_cpu_preempt_check+0x20/0x40 lib/smp_processor_id.c:64
CPU: 0 UID: 0 PID: 5537 Comm: syz.0.1012 Tainted: G             L      syzkaller #0 PREEMPT 
Tainted: [L]=SOFTLOCKUP
Hardware name: linux,dummy-virt (DT)
Call trace:
 show_stack+0x18/0x24 arch/arm64/kernel/stacktrace.c:499 (C)
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x7c/0xb0 lib/dump_stack.c:120
 dump_stack+0x1c/0x28 lib/dump_stack.c:129
 check_preemption_disabled+0xe0/0xe8 lib/smp_processor_id.c:47
 __this_cpu_preempt_check+0x20/0x40 lib/smp_processor_id.c:64
 __arch_counter_get_cntvct_stable arch/arm64/include/asm/arch_timer.h:195 [inline]
 __delay+0x10c/0x374 arch/arm64/lib/delay.c:55
 __const_udelay+0x48/0x64 arch/arm64/lib/delay.c:66
 udelay include/asm-generic/delay.h:62 [inline]
 snd_timer_close_locked+0x258/0x94c sound/core/timer.c:443
 snd_timer_close+0xa4/0x120 sound/core/timer.c:476
 snd_seq_timer_close+0x88/0xd0 sound/core/seq/seq_timer.c:311
 queue_delete+0x50/0xac sound/core/seq/seq_queue.c:126
 snd_seq_queue_delete+0x2c/0x58 sound/core/seq/seq_queue.c:188
 snd_seq_ioctl_delete_queue+0x6c/0xa0 sound/core/seq/seq_clientmgr.c:1546
 call_seq_client_ctl+0x94/0x120 sound/core/seq/seq_clientmgr.c:2419
 snd_seq_kernel_client_ctl+0x68/0x100 sound/core/seq/seq_clientmgr.c:2447
 delete_seq_queue.isra.0+0xbc/0x124 sound/core/seq/oss/seq_oss_init.c:371
 snd_seq_oss_release+0x13c/0x1a0 sound/core/seq/oss/seq_oss_init.c:416
 odev_release+0x4c/0x88 sound/core/seq/oss/seq_oss.c:141
 __fput+0x2d0/0x958 fs/file_table.c:469
 ____fput+0x14/0x20 fs/file_table.c:497
 task_work_run+0x134/0x238 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0x194/0x1c8 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 exit_to_user_mode_prepare_legacy include/linux/irq-entry-common.h:242 [inline]
 arm64_exit_to_user_mode arch/arm64/kernel/entry-common.c:81 [inline]
 el0_svc+0x258/0x29c arch/arm64/kernel/entry-common.c:725
 el0t_64_sync_handler+0xa0/0xe4 arch/arm64/kernel/entry-common.c:743
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596
BUG: using __this_cpu_read() in preemptible [00000000] code: syz.0.1012/5537
caller is __this_cpu_preempt_check+0x20/0x40 lib/smp_processor_id.c:64
CPU: 0 UID: 0 PID: 5537 Comm: syz.0.1012 Tainted: G             L      syzkaller #0 PREEMPT 
Tainted: [L]=SOFTLOCKUP
Hardware name: linux,dummy-virt (DT)
Call trace:
 show_stack+0x18/0x24 arch/arm64/kernel/stacktrace.c:499 (C)
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x7c/0xb0 lib/dump_stack.c:120
 dump_stack+0x1c/0x28 lib/dump_stack.c:129
 check_preemption_disabled+0xe0/0xe8 lib/smp_processor_id.c:47
 __this_cpu_preempt_check+0x20/0x40 lib/smp_processor_id.c:64
 __arch_counter_get_cntvct_stable arch/arm64/include/asm/arch_timer.h:195 [inline]
 __delay+0x19c/0x374 arch/arm64/lib/delay.c:59
 __const_udelay+0x48/0x64 arch/arm64/lib/delay.c:66
 udelay include/asm-generic/delay.h:62 [inline]
 snd_timer_close_locked+0x258/0x94c sound/core/timer.c:443
 snd_timer_close+0xa4/0x120 sound/core/timer.c:476
 snd_seq_timer_close+0x88/0xd0 sound/core/seq/seq_timer.c:311
 queue_delete+0x50/0xac sound/core/seq/seq_queue.c:126
 snd_seq_queue_delete+0x2c/0x58 sound/core/seq/seq_queue.c:188
 snd_seq_ioctl_delete_queue+0x6c/0xa0 sound/core/seq/seq_clientmgr.c:1546
 call_seq_client_ctl+0x94/0x120 sound/core/seq/seq_clientmgr.c:2419
 snd_seq_kernel_client_ctl+0x68/0x100 sound/core/seq/seq_clientmgr.c:2447
 delete_seq_queue.isra.0+0xbc/0x124 sound/core/seq/oss/seq_oss_init.c:371
 snd_seq_oss_release+0x13c/0x1a0 sound/core/seq/oss/seq_oss_init.c:416
 odev_release+0x4c/0x88 sound/core/seq/oss/seq_oss.c:141
 __fput+0x2d0/0x958 fs/file_table.c:469
 ____fput+0x14/0x20 fs/file_table.c:497
 task_work_run+0x134/0x238 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0x194/0x1c8 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 exit_to_user_mode_prepare_legacy include/linux/irq-entry-common.h:242 [inline]
 arm64_exit_to_user_mode arch/arm64/kernel/entry-common.c:81 [inline]
 el0_svc+0x258/0x29c arch/arm64/kernel/entry-common.c:725
 el0t_64_sync_handler+0xa0/0xe4 arch/arm64/kernel/entry-common.c:743
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596

---
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 at googlegroups.com.

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