KCSAN: data-race in isolate_migratepages_block / isolate_migratepages_block (10)

Status: moderation: reported on 2026/10/07 20:25
Subsystems: mm
Labels: race:benign
[Documentation on labels]
Reported-by: syzbot+7b8206619329ea9daa76@syzkaller.appspotmail.com
First crash: 20h50m, last: 20h50m
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
9771e6f9 assessment-kcsan Benign: ✅ ❓ KCSAN: data-race in isolate_migratepages_block / isolate_migratepages_block (10) 2026/10/07 20:24 2026/10/07 20:25 2026/10/07 21:33 f8f239cf
▶ ▼ Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in isolate_migratepages_block / isolate_migratepages_block (3) mm 6 161 1993d 2131d 0/29 auto-closed as invalid on 2021/05/29 14:14
upstream KCSAN: data-race in isolate_migratepages_block / isolate_migratepages_block mm 6 1 2451d 2451d 0/29 auto-closed as invalid on 2020/04/01 04:50
upstream KCSAN: data-race in isolate_migratepages_block / isolate_migratepages_block (8) mm 6 1 967d 967d 0/29 auto-obsoleted due to no activity on 2024/03/19 21:54
upstream KCSAN: data-race in isolate_migratepages_block / isolate_migratepages_block (9) mm 6 6 792d 803d 0/29 auto-obsoleted due to no activity on 2024/09/10 21:33
upstream KCSAN: data-race in isolate_migratepages_block / isolate_migratepages_block (6) mm 6 1 1264d 1264d 0/29 auto-obsoleted due to no activity on 2023/05/28 14:16
upstream KCSAN: data-race in isolate_migratepages_block / isolate_migratepages_block (4) mm 6 1 1885d 1885d 0/29 auto-closed as invalid on 2021/09/14 06:37
upstream KCSAN: data-race in isolate_migratepages_block / isolate_migratepages_block (2) mm 6 1 2259d 2259d 0/29 auto-closed as invalid on 2020/09/05 12:48
upstream KCSAN: data-race in isolate_migratepages_block / isolate_migratepages_block (7) mm 6 1 1107d 1107d 0/29 auto-obsoleted due to no activity on 2023/10/31 19:28
upstream KCSAN: data-race in isolate_migratepages_block / isolate_migratepages_block (5) mm 6 1 1480d 1480d 0/29 auto-obsoleted due to no activity on 2022/10/24 05:31

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

write to 0xffff88823fffa658 of 8 bytes by task 14808 on cpu 0:
 update_cached_migrate mm/compaction.c:450 [inline]
 isolate_migratepages_block+0x1aec/0x1cc0 mm/compaction.c:1311
 isolate_migratepages mm/compaction.c:2177 [inline]
 compact_zone+0x1bd9/0x2790 mm/compaction.c:2668
 compact_node mm/compaction.c:2945 [inline]
 compact_nodes mm/compaction.c:2967 [inline]
 sysctl_compaction_handler+0x2e9/0x550 mm/compaction.c:3018
 proc_sys_call_handler+0x2ec/0x4a0 fs/proc/proc_sysctl.c:600
 proc_sys_write+0x22/0x30 fs/proc/proc_sysctl.c:626
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x57f/0x9a0 fs/read_write.c:687
 ksys_write+0xdc/0x1a0 fs/read_write.c:739
 __do_sys_write fs/read_write.c:750 [inline]
 __se_sys_write fs/read_write.c:747 [inline]
 __x64_sys_write+0x40/0x50 fs/read_write.c:747
 x64_sys_call+0x154e/0x2550 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88823fffa658 of 8 bytes by task 14813 on cpu 1:
 update_cached_migrate mm/compaction.c:449 [inline]
 isolate_migratepages_block+0x1ac8/0x1cc0 mm/compaction.c:1311
 isolate_migratepages mm/compaction.c:2177 [inline]
 compact_zone+0x1bd9/0x2790 mm/compaction.c:2668
 compact_node mm/compaction.c:2945 [inline]
 compact_nodes mm/compaction.c:2967 [inline]
 sysctl_compaction_handler+0x2e9/0x550 mm/compaction.c:3018
 proc_sys_call_handler+0x2ec/0x4a0 fs/proc/proc_sysctl.c:600
 proc_sys_write+0x22/0x30 fs/proc/proc_sysctl.c:626
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x57f/0x9a0 fs/read_write.c:687
 ksys_write+0xdc/0x1a0 fs/read_write.c:739
 __do_sys_write fs/read_write.c:750 [inline]
 __se_sys_write fs/read_write.c:747 [inline]
 __x64_sys_write+0x40/0x50 fs/read_write.c:747
 x64_sys_call+0x154e/0x2550 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x000000000005dc00 -> 0x000000000005e000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 14813 Comm: syz.7.2766 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/07 20:24 upstream 602042bf29f6 6520ecdb .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in isolate_migratepages_block / isolate_migratepages_block
* Struck through repros no longer work on HEAD.