syzbot


KCSAN: data-race in __percpu_counter_init_many / copy_mm (2)

Status: moderation: reported on 2025/09/14 12:23
Subsystems: mm
[Documentation on labels]
Reported-by: syzbot+56d2444ea61a650527b7@syzkaller.appspotmail.com
First crash: 15h38m, last: 15h38m
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __percpu_counter_init_many / copy_mm mm 6 5 61d 118d 0/29 auto-obsoleted due to no activity on 2025/09/09 11:25

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __percpu_counter_init_many / copy_mm

write to 0xffff8881032d6bb0 of 8 bytes by task 17638 on cpu 0:
 __list_add include/linux/list.h:153 [inline]
 list_add include/linux/list.h:169 [inline]
 __percpu_counter_init_many+0x292/0x310 lib/percpu_counter.c:220
 mm_init+0x69d/0x7f0 kernel/fork.c:1082
 dup_mm kernel/fork.c:1481 [inline]
 copy_mm+0x101/0x370 kernel/fork.c:1537
 copy_process+0xd08/0x2000 kernel/fork.c:2175
 kernel_clone+0x16c/0x5c0 kernel/fork.c:2605
 __do_sys_clone kernel/fork.c:2748 [inline]
 __se_sys_clone kernel/fork.c:2732 [inline]
 __x64_sys_clone+0xe6/0x120 kernel/fork.c:2732
 x64_sys_call+0x119c/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:57
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881032d6780 of 1408 bytes by task 22981 on cpu 1:
 dup_mm kernel/fork.c:1479 [inline]
 copy_mm+0xe2/0x370 kernel/fork.c:1537
 copy_process+0xd08/0x2000 kernel/fork.c:2175
 kernel_clone+0x16c/0x5c0 kernel/fork.c:2605
 __do_sys_clone kernel/fork.c:2748 [inline]
 __se_sys_clone kernel/fork.c:2732 [inline]
 __x64_sys_clone+0xe6/0x120 kernel/fork.c:2732
 x64_sys_call+0x119c/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:57
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 22981 Comm: syz.7.7398 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/14 12:22 upstream f83a4f2a4d8c e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __percpu_counter_init_many / copy_mm
* Struck through repros no longer work on HEAD.