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BUG: KCSAN: data-race in lru_add_drain_all / mark_page_accessed

read-write to 0xffff88813bc27b70 of 1 bytes by task 18400 on cpu 0:
 pagevec_add include/linux/pagevec.h:78 [inline]
 activate_page mm/swap.c:349 [inline]
 mark_page_accessed+0x37e/0x5e0 mm/swap.c:434
 shmem_file_read_iter+0x30d/0x760 mm/shmem.c:2646
 call_read_iter include/linux/fs.h:1895 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 vfs_read+0x552/0x5c0 fs/read_write.c:496
 ksys_read+0xce/0x180 fs/read_write.c:634
 __do_sys_read fs/read_write.c:644 [inline]
 __se_sys_read fs/read_write.c:642 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:642
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88813bc27b70 of 1 bytes by task 1659 on cpu 1:
 pagevec_count include/linux/pagevec.h:65 [inline]
 need_activate_page_drain mm/swap.c:337 [inline]
 lru_add_drain_all+0x216/0x3c0 mm/swap.c:828
 khugepaged_do_scan+0x47/0x320 mm/khugepaged.c:2202
 khugepaged+0x75/0x650 mm/khugepaged.c:2263
 kthread+0x1fd/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1659 Comm: khugepaged Not tainted 5.11.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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