On Tue, Apr 29, 2025 at 10:18:04PM +0800, Jianzhou Zhao wrote:
Hello, I found a potential bug titled " possible deadlock in perf_ctx_lock " with modified syzkaller in the Linux6.12.25(longterm maintenance, last updated on April 25, 2025)
Nah, you hit a WARN and then printk being lousy made it explode worse.
WARNING: CPU: 0 PID: 15835 at kernel/trace/trace_event_perf.c:375 perf_trace_add+0x2da/0x390 kernel/trace/trace_event_perf.c:375 Modules linked in: CPU: 0 UID: 0 PID: 15835 Comm: syz.9.499 Not tainted 6.12.25 #3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 RIP: 0010:perf_trace_add+0x2da/0x390 kernel/trace/trace_event_perf.c:375 Code: fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 64 48 89 ab f8 01 00 00 48 89 df e8 b1 ab 26 00 e9 f3 fd ff ff e8 37 87 f6 ff 90 <0f> 0b 90 41 bc ea ff ff ff e9 77 ff ff ff e8 23 c5 56 00 e9 8a fd RSP: 0018:ffffc9000713f7f0 EFLAGS: 00010006 RAX: 0000000040000002 RBX: ffff88802a069880 RCX: ffffffff8195a68e RDX: ffff888045ec2500 RSI: ffffffff8195a839 RDI: ffffffff8deabf48 RBP: 0000000000000000 R08: 0000000000000001 R09: fffff52000e27eef R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffffffff8deabee0 R14: ffff88802a069928 R15: ffff888051237200 FS: 00007fe4fec1c640(0000) GS:ffff88802b800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f50219e7bac CR3: 00000000743bc000 CR4: 0000000000752ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 80000000 Call Trace:
<TASK> event_sched_in+0x434/0xac0 kernel/events/core.c:2629 group_sched_in kernel/events/core.c:2662 [inline] merge_sched_in+0x895/0x1570 kernel/events/core.c:3940 visit_groups_merge.constprop.0.isra.0+0x6d2/0x1250 kernel/events/core.c:3885 pmu_groups_sched_in kernel/events/core.c:3967 [inline] __pmu_ctx_sched_in kernel/events/core.c:3979 [inline] ctx_sched_in+0x5c1/0xa30 kernel/events/core.c:4030 perf_event_sched_in+0x5d/0x90 kernel/events/core.c:2760 perf_event_context_sched_in kernel/events/core.c:4077 [inline] __perf_event_task_sched_in+0x33a/0x6f0 kernel/events/core.c:4106 perf_event_task_sched_in include/linux/perf_event.h:1524 [inline] finish_task_switch.isra.0+0x5f9/0xcb0 kernel/sched/core.c:5201 context_switch kernel/sched/core.c:5335 [inline] __schedule+0x1156/0x5b20 kernel/sched/core.c:6710 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7032 irqentry_exit+0x36/0x90 kernel/entry/common.c:354 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
Not quite sure which of the WARNs that is, as I don't keep the stable trees around and .12 is quite old by now.
Anyway, if you can reproduce I'll take a look.