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BUG: KCSAN: data-race in __lru_cache_add / lru_add_drain_all

read to 0xffff88812c0299e0 of 1 bytes by task 8790 on cpu 1:
 lru_add_drain_all+0x17e/0x3d0 mm/swap.c:746
 migrate_prep+0x17/0x20 mm/migrate.c:72
 do_mbind+0x302/0xa40 mm/mempolicy.c:1282
 kernel_mbind+0x111/0x130 mm/mempolicy.c:1438
 __do_sys_mbind mm/mempolicy.c:1445 [inline]
 __se_sys_mbind mm/mempolicy.c:1441 [inline]
 __x64_sys_mbind+0x89/0xb0 mm/mempolicy.c:1441
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff88812c0299e0 of 1 bytes by task 8817 on cpu 0:
 pagevec_add include/linux/pagevec.h:81 [inline]
 __lru_cache_add+0xbf/0x1d0 mm/swap.c:410
 lru_cache_add+0x1f/0x30 mm/swap.c:447
 add_to_page_cache_lru+0x16a/0x260 mm/filemap.c:959
 pagecache_get_page+0x2ac/0x6f0 mm/filemap.c:1682
 grab_cache_page_write_begin+0x5d/0x90 mm/filemap.c:3259
 ext4_da_write_begin+0x1a3/0x840 fs/ext4/inode.c:2965
 generic_perform_write+0x136/0x320 mm/filemap.c:3309
 ext4_buffered_write_iter+0x143/0x290 fs/ext4/file.c:252
 ext4_file_write_iter+0xf4/0xd40 fs/ext4/file.c:547
 call_write_iter include/linux/fs.h:1902 [inline]
 new_sync_write+0x388/0x4a0 fs/read_write.c:483
 __vfs_write+0xb1/0xc0 fs/read_write.c:496
 vfs_write fs/read_write.c:558 [inline]
 vfs_write+0x18a/0x390 fs/read_write.c:542
 ksys_write+0xd5/0x1b0 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __x64_sys_write+0x4c/0x60 fs/read_write.c:620
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8817 Comm: syz-executor.1 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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