KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch

Status: moderation: reported on 2026/08/19 20:57
Subsystems: trace
Labels: race:benign prio:low
[Documentation on labels]
Reported-by: syzbot+0f695b38e92691e0bd5f@syzkaller.appspotmail.com
First crash: 56d, last: 7h36m
▶ ▼ ✨ AI Jobs (3)
ID Workflow Result Correct Bug Created Started Finished Revision
a9a5ef43 repro-c Reproduced: ✅ ❓ KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch 2026/09/29 01:19 2026/09/29 01:19 2026/09/29 01:46 58f15308
b89c9dcf assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch 2026/08/21 00:01 2026/08/21 00:01 2026/08/21 00:34 1e72964b
754f90a5 assessment-kcsan Benign: ✅ ❓ KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch 2026/08/19 20:57 2026/08/19 20:57 2026/08/19 21:22 1e72964b
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/09/29 04:47 9m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 72d3fcf802c45d00b300f25b848a93c3a2bd7c7e report job log log

Sample crash report:
==================================================================
BUG: KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch

write to 0xffffffff89601220 of 4 bytes by task 9660 on cpu 1:
 tracing_start_sched_switch+0x8d/0x200 kernel/trace/trace_sched_switch.c:101
 tracing_start_cmdline_record+0x13/0x20 kernel/trace/trace_sched_switch.c:135
 __ftrace_event_enable_disable+0x203/0x4b0 kernel/trace/trace_events.c:894
 ftrace_event_enable_disable kernel/trace/trace_events.c:934 [inline]
 __ftrace_set_clr_event_nolock+0x39e/0x820 kernel/trace/trace_events.c:1404
 __ftrace_set_clr_event kernel/trace/trace_events.c:1437 [inline]
 ftrace_set_clr_event+0x2a6/0x340 kernel/trace/trace_events.c:1487
 ftrace_event_write+0x170/0x1d0 kernel/trace/trace_events.c:1577
 vfs_write+0x254/0x9a0 fs/read_write.c:685
 ksys_write+0xdc/0x1a0 fs/read_write.c:739
 __do_sys_write fs/read_write.c:750 [inline]
 __se_sys_write fs/read_write.c:747 [inline]
 __x64_sys_write+0x40/0x50 fs/read_write.c:747
 x64_sys_call+0x154e/0x2550 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff89601220 of 4 bytes by task 3400 on cpu 0:
 probe_sched_switch+0x46/0xa0 kernel/trace/trace_sched_switch.c:32
 __traceiter_sched_switch+0x3f/0x60 include/trace/events/sched.h:220
 __do_trace_sched_switch include/trace/events/sched.h:220 [inline]
 trace_sched_switch include/trace/events/sched.h:220 [inline]
 __schedule+0xc34/0xd20 kernel/sched/core.c:7281
 __schedule_loop kernel/sched/core.c:7361 [inline]
 schedule+0x5b/0xa0 kernel/sched/core.c:7376
 worker_thread+0x645/0x750 kernel/workqueue.c:3575
 kthread+0x223/0x270 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x0000030b -> 0x0000030c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3400 Comm: kworker/0:4 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Workqueue:  0x0 (mld)
==================================================================

Crashes (23):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/14 16:50 upstream 4056b3c9d3c9 1a71827b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/10/14 11:14 upstream ca3e345926b0 7321cd29 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/10/09 11:40 upstream af32da41b032 b2734a59 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/10/08 22:05 upstream 6c377d19d4a5 b2734a59 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/10/08 22:05 upstream 6c377d19d4a5 b2734a59 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/10/08 01:24 upstream 7b63ef2d55f2 6520ecdb .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/10/07 18:41 upstream 602042bf29f6 6520ecdb .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/10/05 13:30 upstream a90ee4305c4a af63e995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/10/02 11:29 upstream ce1e0223d8ad 6d32eb1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/10/02 00:28 upstream d24e8ac715de f5cdae2f .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/09/30 20:29 upstream 551c722f4080 38f7f0d1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/09/29 22:58 upstream 6f8319e3e9a4 328436b3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/09/28 13:14 upstream 72d3fcf802c4 a3c7249d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/09/25 20:57 upstream aa98230e410f f281d9d2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/09/25 00:41 upstream f49a343b305c 3c3cdf19 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/09/22 23:43 upstream c4e9f74da438 5207b90e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/09/21 20:26 upstream f0100363d8c3 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/09/11 07:15 upstream 08df884136f1 1fe56c0a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/09/08 10:17 upstream 28924df2a08f 680aa3e1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/09/07 00:53 upstream 88405f0ad1d5 4f7b22a0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/09/05 22:39 upstream 0d9ff90a5422 4f7b22a0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/09/05 02:12 upstream bc35965f6940 4f7b22a0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
2026/08/19 20:56 upstream e8bf40d15402 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_switch / tracing_start_sched_switch
* Struck through repros no longer work on HEAD.