KCSAN: assert: race in srcu_gp_start_if

KCSAN: assert: race in srcu_gp_start_if_needed

Status: upstream: reported on 2024/11/24 22:47
Subsystems: perf trace
[Documentation on labels]
Reported-by: syzbot+16a19b06125a2963eaee@syzkaller.appspotmail.com
Fix commit: d31e31365b5b srcu: Force synchronization for srcu_get_delay()
Patched on: [ci-qemu-gce-upstream-auto ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-snapshot-upstream-root ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce], missing on: [ci-qemu-native-arm64-kvm ci-qemu2-arm32 ci-qemu2-riscv64 ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci2-upstream-usb]
First crash: 125d, last: 125d

▶ ▼ Discussions (4)

Title	Replies (including bot)	Last reply
[PATCH rcu 07/20] srcu: Force synchronization for srcu_get_delay()	1 (1)	2025/02/24 02:22
[PATCH rcu v2] 07/20] srcu: Force synchronization for srcu_get_delay()	1 (1)	2025/01/30 19:03
[PATCH rcu 07/17] srcu: Force synchronization for srcu_get_delay()	1 (1)	2025/01/16 20:21
[syzbot] [perf?] [trace?] KCSAN: assert: race in srcu_gp_start_if_needed	2 (3)	2025/01/04 01:14

Sample crash report:

==================================================================
BUG: KCSAN: assert: race in srcu_get_delay kernel/rcu/srcutree.c:658 [inline]
BUG: KCSAN: assert: race in srcu_funnel_gp_start kernel/rcu/srcutree.c:1089 [inline]
BUG: KCSAN: assert: race in srcu_gp_start_if_needed+0x808/0x9f0 kernel/rcu/srcutree.c:1339

race at unknown origin, with assert no writes to 0xffffffff8676ffc8 of 8 bytes by task 6285 on cpu 0:
 srcu_get_delay kernel/rcu/srcutree.c:658 [inline]
 srcu_funnel_gp_start kernel/rcu/srcutree.c:1089 [inline]
 srcu_gp_start_if_needed+0x808/0x9f0 kernel/rcu/srcutree.c:1339
 __call_srcu kernel/rcu/srcutree.c:1384 [inline]
 __synchronize_srcu+0x114/0x150 kernel/rcu/srcutree.c:1432
 synchronize_srcu+0x1ae/0x1d0
 uprobe_unregister_sync+0x1a/0x20 kernel/events/uprobes.c:1328
 __probe_event_disable kernel/trace/trace_uprobe.c:1138 [inline]
 probe_event_disable+0x1f5/0x240 kernel/trace/trace_uprobe.c:1222
 trace_uprobe_register+0xbb/0x3c0 kernel/trace/trace_uprobe.c:1512
 perf_trace_event_unreg+0x6c/0x1a0 kernel/trace/trace_event_perf.c:162
 perf_uprobe_destroy+0x6a/0xf0 kernel/trace/trace_event_perf.c:345
 _free_event+0x7ca/0xa10 kernel/events/core.c:5357
 put_event kernel/events/core.c:5454 [inline]
 perf_event_release_kernel+0x61a/0x670 kernel/events/core.c:5579
 perf_release+0x1f/0x30 kernel/events/core.c:5589
 __fput+0x17a/0x6d0 fs/file_table.c:450
 ____fput+0x1c/0x30 fs/file_table.c:478
 task_work_run+0x13a/0x1a0 kernel/task_work.c:239
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xa8/0x120 kernel/entry/common.c:218
 do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0x0000000000000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 6285 Comm: syz.1.1056 Not tainted 6.12.0-syzkaller-08756-g42d9e8b7ccdd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================

Crashes (1):
Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Assets (help?)	Manager	Title
2024/11/24 00:35	upstream	42d9e8b7ccdd	68da6d95	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci2-upstream-kcsan-gce	KCSAN: assert: race in srcu_gp_start_if_needed

* ~~Struck through~~ repros no longer work on HEAD.