syzbot


KCSAN: data-race in event_sched_out / perf_event_update_userpage (5)

Status: auto-closed as invalid on 2021/10/30 02:46
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 434d, last: 434d
similar bugs (6):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in event_sched_out / perf_event_update_userpage (3) 2 548d 559d 0/24 auto-closed as invalid on 2021/07/08 04:06
upstream KCSAN: data-race in event_sched_out / perf_event_update_userpage (6) 1 383d 383d 0/24 auto-closed as invalid on 2021/12/20 08:52
upstream KCSAN: data-race in event_sched_out / perf_event_update_userpage (7) 2 333d 340d 0/24 auto-closed as invalid on 2022/02/08 01:10
upstream KCSAN: data-race in event_sched_out / perf_event_update_userpage 1 765d 765d 0/24 auto-closed as invalid on 2020/12/02 23:00
upstream KCSAN: data-race in event_sched_out / perf_event_update_userpage (4) 1 484d 484d 0/24 auto-closed as invalid on 2021/09/10 05:35
upstream KCSAN: data-race in event_sched_out / perf_event_update_userpage (2) 1 595d 595d 0/24 auto-closed as invalid on 2021/05/21 17:09

Sample crash report:
==================================================================
BUG: KCSAN: data-race in event_sched_out / perf_event_update_userpage

write to 0xffff88813da0ac68 of 8 bytes by task 26604 on cpu 1:
 perf_event_update_time kernel/events/core.c:647 [inline]
 perf_event_set_state kernel/events/core.c:666 [inline]
 event_sched_out+0x315/0x7f0 kernel/events/core.c:2293
 group_sched_out+0xbf/0x1a0 kernel/events/core.c:2319
 ctx_sched_out+0x36f/0x410 kernel/events/core.c:3289
 task_ctx_sched_out kernel/events/core.c:2687 [inline]
 perf_event_context_sched_out kernel/events/core.c:3494 [inline]
 __perf_event_task_sched_out+0x64c/0xec0 kernel/events/core.c:3597
 perf_event_task_sched_out include/linux/perf_event.h:1229 [inline]
 prepare_task_switch+0x134/0x140 kernel/sched/core.c:4744
 context_switch kernel/sched/core.c:4892 [inline]
 __schedule+0x382/0x680 kernel/sched/core.c:6287
 schedule+0x67/0x90 kernel/sched/core.c:6366
 exit_to_user_mode_loop kernel/entry/common.c:163 [inline]
 exit_to_user_mode_prepare+0xbb/0x190 kernel/entry/common.c:207
 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:300
 do_syscall_64+0x50/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88813da0ac68 of 8 bytes by task 26599 on cpu 0:
 __perf_update_times kernel/events/core.c:638 [inline]
 calc_timer_values kernel/events/core.c:5786 [inline]
 perf_event_update_userpage+0x107/0x2f0 kernel/events/core.c:5841
 perf_mmap+0xb84/0xd00 kernel/events/core.c:6328
 call_mmap include/linux/fs.h:2168 [inline]
 mmap_region+0xb1a/0x1260 mm/mmap.c:1787
 do_mmap+0x781/0xc20 mm/mmap.c:1575
 vm_mmap_pgoff+0x117/0x1f0 mm/util.c:519
 ksys_mmap_pgoff+0x284/0x350 mm/mmap.c:1624
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000000000043d9 -> 0x0000000000006f57

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 26599 Comm: syz-executor.0 Tainted: G        W         5.15.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-upstream-kcsan-gce 2021/09/25 02:40 upstream 7d42e9818258 8cac236e .config log report info KCSAN: data-race in event_sched_out / perf_event_update_userpage
* Struck through repros no longer work on HEAD.