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: 47d, last: 4d02h
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 108d 164d 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 0xffff88811a2c20f0 of 8 bytes by task 6068 on cpu 0:
 __list_add include/linux/list.h:161 [inline]
 list_add include/linux/list.h:177 [inline]
 __percpu_counter_init_many+0x292/0x310 lib/percpu_counter.c:220
 mm_init+0x6ab/0x7f0 kernel/fork.c:1086
 mm_alloc+0x81/0xa0 kernel/fork.c:1121
 bprm_mm_init fs/exec.c:261 [inline]
 alloc_bprm+0x20e/0x350 fs/exec.c:1466
 kernel_execve+0x85/0x660 fs/exec.c:1885
 call_usermodehelper_exec_async+0x197/0x250 kernel/umh.c:109
 ret_from_fork+0x122/0x1b0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff88811a2c1cc0 of 1408 bytes by task 6070 on cpu 1:
 dup_mm kernel/fork.c:1483 [inline]
 copy_mm+0xe2/0x370 kernel/fork.c:1541
 copy_process+0xd08/0x2000 kernel/fork.c:2181
 kernel_clone+0x16c/0x5c0 kernel/fork.c:2609
 __do_sys_clone kernel/fork.c:2750 [inline]
 __se_sys_clone kernel/fork.c:2734 [inline]
 __x64_sys_clone+0xe6/0x120 kernel/fork.c:2734
 x64_sys_call+0x119c/0x3000 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: 6070 Comm: dhcpcd-run-hook Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/27 13:06 upstream dcb6fa37fd7b fd2207e7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __percpu_counter_init_many / copy_mm
2025/10/12 20:32 upstream 8765f467912f ff1712fe .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __percpu_counter_init_many / copy_mm
2025/10/02 23:10 upstream 7f7072574127 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __percpu_counter_init_many / copy_mm
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.