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BUG: KCSAN: data-race in compact_zone / compact_zone

write to 0xffff88812fffcc10 of 8 bytes by task 12456 on cpu 1:
 update_cached_migrate mm/compaction.c:418 [inline]
 isolate_migratepages mm/compaction.c:1824 [inline]
 compact_zone+0x97f/0x1fc0 mm/compaction.c:2181
 compact_zone_order+0x1c0/0x220 mm/compaction.c:2323
 try_to_compact_pages+0x1b9/0x610 mm/compaction.c:2376
 __alloc_pages_direct_compact+0x80/0x150 mm/page_alloc.c:3959
 __alloc_pages_slowpath.constprop.0+0x440/0xd90 mm/page_alloc.c:4615
 __alloc_pages_nodemask+0x2bd/0x300 mm/page_alloc.c:4822
 __alloc_pages include/linux/gfp.h:504 [inline]
 __alloc_pages_node include/linux/gfp.h:517 [inline]
 alloc_pages_vma+0x29b/0x390 mm/mempolicy.c:2239
 do_huge_pmd_anonymous_page+0x2af/0x1000 mm/huge_memory.c:772
 create_huge_pmd mm/memory.c:4097 [inline]
 __handle_mm_fault+0x2d79/0x2ec0 mm/memory.c:4316
 handle_mm_fault+0x21c/0x540 mm/memory.c:4382
 faultin_page mm/gup.c:879 [inline]
 __get_user_pages+0x533/0x11c0 mm/gup.c:1098
 __get_user_pages_locked mm/gup.c:1284 [inline]
 __get_user_pages_remote mm/gup.c:1835 [inline]
 __get_user_pages_remote+0x164/0x590 mm/gup.c:1810
 pin_user_pages_remote+0x71/0xb0 mm/gup.c:2901
 process_vm_rw_single_vec mm/process_vm_access.c:108 [inline]
 process_vm_rw_core.isra.0+0x34d/0x760 mm/process_vm_access.c:218
 process_vm_rw+0x1c4/0x1e0 mm/process_vm_access.c:286
 __do_sys_process_vm_writev mm/process_vm_access.c:308 [inline]
 __se_sys_process_vm_writev mm/process_vm_access.c:303 [inline]
 __x64_sys_process_vm_writev+0x80/0xa0 mm/process_vm_access.c:303
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812fffcc10 of 8 bytes by task 12457 on cpu 0:
 update_cached_migrate mm/compaction.c:417 [inline]
 isolate_migratepages mm/compaction.c:1824 [inline]
 compact_zone+0x95b/0x1fc0 mm/compaction.c:2181
 compact_zone_order+0x1c0/0x220 mm/compaction.c:2323
 try_to_compact_pages+0x1b9/0x610 mm/compaction.c:2376
 __alloc_pages_direct_compact+0x80/0x150 mm/page_alloc.c:3959
 __alloc_pages_slowpath.constprop.0+0x203/0xd90 mm/page_alloc.c:4533
 __alloc_pages_nodemask+0x2bd/0x300 mm/page_alloc.c:4822
 __alloc_pages include/linux/gfp.h:504 [inline]
 __alloc_pages_node include/linux/gfp.h:517 [inline]
 alloc_pages_vma+0x29b/0x390 mm/mempolicy.c:2239
 do_huge_pmd_anonymous_page+0x2af/0x1000 mm/huge_memory.c:772
 create_huge_pmd mm/memory.c:4097 [inline]
 __handle_mm_fault+0x2d79/0x2ec0 mm/memory.c:4316
 handle_mm_fault+0x21c/0x540 mm/memory.c:4382
 faultin_page mm/gup.c:879 [inline]
 __get_user_pages+0x533/0x11c0 mm/gup.c:1098
 __get_user_pages_locked mm/gup.c:1284 [inline]
 __get_user_pages_remote mm/gup.c:1835 [inline]
 __get_user_pages_remote+0x164/0x590 mm/gup.c:1810
 pin_user_pages_remote+0x71/0xb0 mm/gup.c:2901
 process_vm_rw_single_vec mm/process_vm_access.c:108 [inline]
 process_vm_rw_core.isra.0+0x34d/0x760 mm/process_vm_access.c:218
 process_vm_rw+0x1c4/0x1e0 mm/process_vm_access.c:286
 __do_sys_process_vm_writev mm/process_vm_access.c:308 [inline]
 __se_sys_process_vm_writev mm/process_vm_access.c:303 [inline]
 __x64_sys_process_vm_writev+0x80/0xa0 mm/process_vm_access.c:303
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 12457 Comm: syz-executor.3 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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