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BUG: KCSAN: data-race in kswapd / wakeup_kswapd

read to 0xffff88821fffca84 of 4 bytes by task 9322 on cpu 0:
 wakeup_kswapd+0xc9/0x3f0 mm/vmscan.c:3985
 wake_all_kswapds+0x54/0xb0 mm/page_alloc.c:4178
 __alloc_pages_slowpath+0xc76/0xee0 mm/page_alloc.c:4449
 __alloc_pages_nodemask+0x2c8/0x310 mm/page_alloc.c:4776
 alloc_pages_current+0xd1/0x170 mm/mempolicy.c:2192
 alloc_pages include/linux/gfp.h:532 [inline]
 relay_alloc_buf kernel/relay.c:136 [inline]
 relay_create_buf kernel/relay.c:177 [inline]
 relay_open_buf.part.0+0x219/0x600 kernel/relay.c:452
 relay_open_buf kernel/relay.c:449 [inline]
 relay_open kernel/relay.c:599 [inline]
 relay_open+0x381/0x5e0 kernel/relay.c:563
 do_blk_trace_setup+0x2aa/0x5f0 kernel/trace/blktrace.c:526
 __blk_trace_setup+0x81/0x110 kernel/trace/blktrace.c:571
 blk_trace_ioctl+0xe2/0x1d0 kernel/trace/blktrace.c:710
 blkdev_ioctl+0xc6/0x1160 block/ioctl.c:592
 block_ioctl+0x95/0xc0 fs/block_dev.c:1954
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0x991/0xc60 fs/ioctl.c:696
 ksys_ioctl+0xbd/0xe0 fs/ioctl.c:713
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0x4c/0x60 fs/ioctl.c:718
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff88821fffca84 of 4 bytes by task 1775 on cpu 1:
 kswapd_try_to_sleep mm/vmscan.c:3839 [inline]
 kswapd+0x51d/0x800 mm/vmscan.c:3926
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1775 Comm: kswapd1 Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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