syzbot

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BUG: KCSAN: data-race in compact_zone / compact_zone

write to 0xffff88823fffad10 of 8 bytes by task 33 on cpu 0:
 update_cached_migrate mm/compaction.c:446 [inline]
 isolate_migratepages mm/compaction.c:2126 [inline]
 compact_zone+0x136d/0x2900 mm/compaction.c:2617
 kcompactd_do_work mm/compaction.c:3098 [inline]
 kcompactd+0x4a2/0xd50 mm/compaction.c:3192
 kthread+0x489/0x510 kernel/kthread.c:463
 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 0xffff88823fffad10 of 8 bytes by task 24806 on cpu 1:
 update_cached_migrate mm/compaction.c:445 [inline]
 isolate_migratepages mm/compaction.c:2126 [inline]
 compact_zone+0x1348/0x2900 mm/compaction.c:2617
 compact_zone_order mm/compaction.c:2782 [inline]
 try_to_compact_pages+0x32f/0x940 mm/compaction.c:2843
 __alloc_pages_direct_compact+0x65/0x1d0 mm/page_alloc.c:4101
 __alloc_pages_slowpath+0x34a/0x5d0 mm/page_alloc.c:4822
 __alloc_frozen_pages_noprof+0x270/0x360 mm/page_alloc.c:5196
 alloc_pages_mpol+0xb3/0x260 mm/mempolicy.c:2416
 alloc_frozen_pages_noprof mm/mempolicy.c:2487 [inline]
 alloc_pages_noprof+0x90/0x130 mm/mempolicy.c:2507
 vm_area_alloc_pages mm/vmalloc.c:3647 [inline]
 __vmalloc_area_node mm/vmalloc.c:3724 [inline]
 __vmalloc_node_range_noprof+0x7a5/0xed0 mm/vmalloc.c:3897
 __kvmalloc_node_noprof+0x483/0x670 mm/slub.c:7130
 kvmalloc_array_node_noprof include/linux/slab.h:1122 [inline]
 __ptr_ring_init_queue_alloc_noprof include/linux/ptr_ring.h:481 [inline]
 ptr_ring_init_noprof include/linux/ptr_ring.h:499 [inline]
 skb_array_init_noprof include/linux/skb_array.h:182 [inline]
 pfifo_fast_init+0x266/0x360 net/sched/sch_generic.c:869
 qdisc_create_dflt+0xef/0x2d0 net/sched/sch_generic.c:1019
 mq_init+0x1b6/0x380 net/sched/sch_mq.c:90
 qdisc_create_dflt+0xef/0x2d0 net/sched/sch_generic.c:1019
 attach_default_qdiscs net/sched/sch_generic.c:1201 [inline]
 dev_activate+0xde/0x9e0 net/sched/sch_generic.c:1255
 __dev_open+0x472/0x530 net/core/dev.c:1691
 __dev_change_flags+0x163/0x400 net/core/dev.c:9637
 netif_change_flags+0x5a/0xd0 net/core/dev.c:9700
 dev_change_flags+0xce/0x180 net/core/dev_api.c:68
 dev_ifsioc+0x44b/0xaa0 net/core/dev_ioctl.c:579
 dev_ioctl+0x70a/0x960 net/core/dev_ioctl.c:838
 sock_do_ioctl+0x197/0x220 net/socket.c:1268
 sock_ioctl+0x41b/0x610 net/socket.c:1375
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xce/0x140 fs/ioctl.c:583
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:583
 x64_sys_call+0x1816/0x3000 arch/x86/include/generated/asm/syscalls_64.h:17
 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: 0x0000000000231a00 -> 0x0000000000236200

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 24806 Comm: syz.3.7291 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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syzkaller0: default qdisc (pfifo_fast) fail, fallback to noqueue