[moderation] [mm?] KCSAN: data-race in compact_zone / compact_zone (9)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 74fe02ce122a Merge tag 'wq-for-7.1-rc2-fixes' of git://git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11f495ce580000
kernel config: https://syzkaller.appspot.com/x/.config?x=2e40c0f41e01837e
dashboard link: https://syzkaller.appspot.com/bug?extid=47e944ec864ad92c64ea
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [ak...@linux-foundation.org han...@cmpxchg.org jack...@google.com linux-...@vger.kernel.org linu...@kvack.org mho...@suse.com sur...@google.com vba...@kernel.org z...@nvidia.com]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a987e04ae537/disk-74fe02ce.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/708a920d1eab/vmlinux-74fe02ce.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f6f9b1ea55ac/bzImage-74fe02ce.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+47e944...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in compact_zone / compact_zone

write to 0xffff88823fffab98 of 8 bytes by task 10995 on cpu 1:
compact_zone+0x1e81/0x2720 mm/compaction.c:2642
compact_zone_order mm/compaction.c:2799 [inline]
try_to_compact_pages+0x3ca/0x960 mm/compaction.c:2860
__alloc_pages_direct_compact+0x64/0x3b0 mm/page_alloc.c:4157
__alloc_pages_slowpath+0x25a/0x600 mm/page_alloc.c:4830
__alloc_frozen_pages_noprof+0x270/0x350 mm/page_alloc.c:5239
alloc_pages_mpol+0xb3/0x260 mm/mempolicy.c:2490
alloc_frozen_pages_noprof mm/mempolicy.c:2561 [inline]
alloc_pages_noprof+0x8f/0x140 mm/mempolicy.c:2581
vm_area_alloc_pages mm/vmalloc.c:3728 [inline]
__vmalloc_area_node mm/vmalloc.c:3878 [inline]
__vmalloc_node_range_noprof+0xaed/0x11c0 mm/vmalloc.c:4064
__kvmalloc_node_noprof+0x3d4/0x640 mm/slub.c:6860
futex_hash_allocate+0x190/0x9a0 kernel/futex/core.c:1815
futex_hash_prctl+0xd8/0xf0 kernel/futex/core.c:1961
__do_sys_prctl kernel/sys.c:2885 [inline]
__se_sys_prctl+0x4f4/0x1400 kernel/sys.c:2534
__x64_sys_prctl+0x67/0x80 kernel/sys.c:2534
x64_sys_call+0x2533/0x3020 arch/x86/include/generated/asm/syscalls_64.h:158
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff88823fffab98 of 8 bytes by task 11022 on cpu 0:
compact_zone+0x1e81/0x2720 mm/compaction.c:2642
compact_zone_order mm/compaction.c:2799 [inline]
try_to_compact_pages+0x3ca/0x960 mm/compaction.c:2860
__alloc_pages_direct_compact+0x64/0x3b0 mm/page_alloc.c:4157
__alloc_pages_slowpath+0x25a/0x600 mm/page_alloc.c:4830
__alloc_frozen_pages_noprof+0x270/0x350 mm/page_alloc.c:5239
alloc_pages_mpol+0xb3/0x260 mm/mempolicy.c:2490
alloc_frozen_pages_noprof mm/mempolicy.c:2561 [inline]
alloc_pages_noprof+0x8f/0x140 mm/mempolicy.c:2581
vm_area_alloc_pages mm/vmalloc.c:3728 [inline]
__vmalloc_area_node mm/vmalloc.c:3878 [inline]
__vmalloc_node_range_noprof+0xaed/0x11c0 mm/vmalloc.c:4064
__kvmalloc_node_noprof+0x3d4/0x640 mm/slub.c:6860
futex_hash_allocate+0x190/0x9a0 kernel/futex/core.c:1815
futex_hash_prctl+0xd8/0xf0 kernel/futex/core.c:1961
__do_sys_prctl kernel/sys.c:2885 [inline]
__se_sys_prctl+0x4f4/0x1400 kernel/sys.c:2534
__x64_sys_prctl+0x67/0x80 kernel/sys.c:2534
x64_sys_call+0x2533/0x3020 arch/x86/include/generated/asm/syscalls_64.h:158
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000152e00 -> 0x0000000000155600

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 11022 Comm: syz.8.2101 Tainted: G W syzkaller #0 PREEMPT(full)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
==================================================================


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