syzbot


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

Status: moderation: reported on 2025/09/08 02:56
Subsystems: mm
[Documentation on labels]
Reported-by: syzbot+5f48bf71cf215490faf0@syzkaller.appspotmail.com
First crash: 4d06h, last: 4d06h
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in copy_mm / copy_page_range mm 6 3 82d 137d 0/29 auto-obsoleted due to no activity on 2025/08/17 07:05

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

read-write to 0xffff888103d5fa60 of 4 bytes by task 7131 on cpu 1:
 do_raw_write_seqcount_begin include/linux/seqlock.h:431 [inline]
 copy_page_range+0x250/0x3c20 mm/memory.c:1400
 dup_mmap+0x885/0xf20 mm/mmap.c:1834
 dup_mm kernel/fork.c:1485 [inline]
 copy_mm+0x11a/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 0xffff888103d5f8c0 of 1408 bytes by task 7132 on cpu 0:
 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: 0 UID: 0 PID: 7132 Comm: syz.7.1141 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/08 02:55 upstream 6ab41fca2e80 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in copy_mm / copy_page_range
* Struck through repros no longer work on HEAD.