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BUG: KCSAN: data-race in lru_add_drain_all / lru_cache_add

write to 0xffff888237c264a8 of 1 bytes by task 894 on cpu 0:
 pagevec_add include/linux/pagevec.h:74 [inline]
 lru_cache_add+0x74/0x130 mm/swap.c:461
 add_to_page_cache_lru+0x150/0x1b0 mm/filemap.c:999
 pagecache_get_page+0x6a3/0x900 mm/filemap.c:1912
 grab_cache_page_write_begin+0x3f/0x70 mm/filemap.c:3626
 ext4_da_write_begin+0x305/0x820 fs/ext4/inode.c:2984
 generic_perform_write+0x196/0x3a0 mm/filemap.c:3676
 ext4_buffered_write_iter+0x2f2/0x3f0 fs/ext4/file.c:269
 ext4_file_write_iter+0x2e7/0x11d0 fs/ext4/file.c:519
 call_write_iter include/linux/fs.h:2116 [inline]
 do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740
 do_iter_write+0x112/0x4c0 fs/read_write.c:866
 vfs_writev fs/read_write.c:939 [inline]
 do_pwritev+0x1e5/0x3a0 fs/read_write.c:1036
 __do_sys_pwritev fs/read_write.c:1083 [inline]
 __se_sys_pwritev fs/read_write.c:1078 [inline]
 __x64_sys_pwritev+0x54/0x60 fs/read_write.c:1078
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888237c264a8 of 1 bytes by task 1777 on cpu 1:
 pagevec_count include/linux/pagevec.h:61 [inline]
 lru_add_drain_all+0x108/0x3b0 mm/swap.c:813
 invalidate_bdev+0x50/0x70 fs/block_dev.c:96
 ext4_put_super+0x5d0/0x8e0 fs/ext4/super.c:1230
 generic_shutdown_super+0xe1/0x230 fs/super.c:465
 kill_block_super+0x4a/0x90 fs/super.c:1395
 deactivate_locked_super+0x65/0xd0 fs/super.c:335
 deactivate_super+0x85/0x90 fs/super.c:366
 cleanup_mnt+0x267/0x2d0 fs/namespace.c:1136
 __cleanup_mnt+0x15/0x20 fs/namespace.c:1143
 task_work_run+0xae/0x130 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x156/0x190 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:301
 do_syscall_64+0x56/0x90 arch/x86/entry/common.c:57
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1777 Comm: syz-executor.3 Tainted: G        W         5.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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