syzbot


KCSAN: data-race in cgroup_freezer_migrate_task / handle_mm_fault (5)

Status: moderation: reported on 2025/07/30 14:01
Subsystems: cgroups
[Documentation on labels]
Reported-by: syzbot+304c2b36a6a4bac6024b@syzkaller.appspotmail.com
First crash: 31d, last: 31d
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in cgroup_freezer_migrate_task / handle_mm_fault (4) cgroups 6 2 1664d 1688d 0/29 auto-closed as invalid on 2021/03/14 16:47
upstream KCSAN: data-race in cgroup_freezer_migrate_task / handle_mm_fault cgroups 6 1 2085d 2085d 0/29 auto-closed as invalid on 2020/02/23 07:27
upstream KCSAN: data-race in cgroup_freezer_migrate_task / handle_mm_fault (2) cgroups 6 1 1797d 1797d 0/29 auto-closed as invalid on 2020/11/02 09:03
upstream KCSAN: data-race in cgroup_freezer_migrate_task / handle_mm_fault (3) cgroups 6 1 1743d 1727d 0/29 auto-closed as invalid on 2020/12/25 21:40

Sample crash report:
==================================================================
BUG: KCSAN: data-race in cgroup_freezer_migrate_task / handle_mm_fault

read-write to 0xffff888117d8c748 of 2 bytes by task 3529 on cpu 0:
 lru_gen_exit_fault mm/memory.c:6310 [inline]
 handle_mm_fault+0x206f/0x2be0 mm/memory.c:6407
 do_user_addr_fault+0x636/0x1090 arch/x86/mm/fault.c:1336
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

read to 0xffff888117d8c748 of 2 bytes by task 3528 on cpu 1:
 cgroup_freezer_migrate_task+0xac/0x290 kernel/cgroup/freezer.c:236
 cgroup_migrate_execute+0x288/0x7f0 kernel/cgroup/cgroup.c:2647
 cgroup_update_dfl_csses kernel/cgroup/cgroup.c:3135 [inline]
 cgroup_apply_control+0x3ab/0x410 kernel/cgroup/cgroup.c:3375
 cgroup_subtree_control_write+0x7d5/0xb80 kernel/cgroup/cgroup.c:3520
 cgroup_file_write+0x197/0x350 kernel/cgroup/cgroup.c:4183
 kernfs_fop_write_iter+0x1be/0x2d0 fs/kernfs/file.c:334
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x49d/0x8e0 fs/read_write.c:686
 ksys_write+0xda/0x1a0 fs/read_write.c:738
 __do_sys_write fs/read_write.c:749 [inline]
 __se_sys_write fs/read_write.c:746 [inline]
 __x64_sys_write+0x40/0x50 fs/read_write.c:746
 x64_sys_call+0x27fe/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:2
 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

value changed: 0x0061 -> 0x0001

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3528 Comm: syz.7.7809 Not tainted 6.16.0-syzkaller-04405-g4b290aae788e #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/30 14:01 upstream 4b290aae788e f8f2b4da .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in cgroup_freezer_migrate_task / handle_mm_fault
* Struck through repros no longer work on HEAD.