syzbot

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BUG: KCSAN: data-race in compaction_deferred / compaction_deferred

read-write to 0xffff88813fffb5b0 of 4 bytes by task 17926 on cpu 1:
 compaction_deferred+0x75/0x160 mm/compaction.c:183
 try_to_compact_pages+0x13c/0x580 mm/compaction.c:2487
 __alloc_pages_direct_compact+0x89/0x1a0 mm/page_alloc.c:4108
 __alloc_pages_slowpath+0x2b5/0x9c0 mm/page_alloc.c:4679
 __alloc_pages_nodemask+0x269/0x350 mm/page_alloc.c:4965
 alloc_pages_current+0x21d/0x310 mm/mempolicy.c:2271
 alloc_pages include/linux/gfp.h:547 [inline]
 ion_page_pool_alloc_pages drivers/staging/android/ion/ion_page_pool.c:19 [inline]
 ion_page_pool_alloc+0x230/0x260 drivers/staging/android/ion/ion_page_pool.c:78
 alloc_buffer_page drivers/staging/android/ion/ion_system_heap.c:53 [inline]
 alloc_largest_available drivers/staging/android/ion/ion_system_heap.c:87 [inline]
 ion_system_heap_allocate+0x18a/0x6b0 drivers/staging/android/ion/ion_system_heap.c:118
 ion_buffer_create drivers/staging/android/ion/ion.c:50 [inline]
 ion_alloc drivers/staging/android/ion/ion.c:366 [inline]
 ion_ioctl+0x2d2/0x9b0 drivers/staging/android/ion/ion.c:492
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:739
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:739
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff88813fffb5b0 of 4 bytes by task 17928 on cpu 0:
 compaction_deferred+0xd5/0x160 mm/compaction.c:184
 try_to_compact_pages+0x13c/0x580 mm/compaction.c:2487
 __alloc_pages_direct_compact+0x89/0x1a0 mm/page_alloc.c:4108
 __alloc_pages_slowpath+0x2b5/0x9c0 mm/page_alloc.c:4679
 __alloc_pages_nodemask+0x269/0x350 mm/page_alloc.c:4965
 alloc_pages_current+0x21d/0x310 mm/mempolicy.c:2271
 alloc_pages include/linux/gfp.h:547 [inline]
 ion_page_pool_alloc_pages drivers/staging/android/ion/ion_page_pool.c:19 [inline]
 ion_page_pool_alloc+0x230/0x260 drivers/staging/android/ion/ion_page_pool.c:78
 alloc_buffer_page drivers/staging/android/ion/ion_system_heap.c:53 [inline]
 alloc_largest_available drivers/staging/android/ion/ion_system_heap.c:87 [inline]
 ion_system_heap_allocate+0x18a/0x6b0 drivers/staging/android/ion/ion_system_heap.c:118
 ion_buffer_create drivers/staging/android/ion/ion.c:50 [inline]
 ion_alloc drivers/staging/android/ion/ion.c:366 [inline]
 ion_ioctl+0x2d2/0x9b0 drivers/staging/android/ion/ion.c:492
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:739
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:739
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 17928 Comm: syz-executor.1 Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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