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BUG: KCSAN: data-race in __add_to_page_cache_locked / filemap_write_and_wait

write to 0xffff88812aba06e8 of 8 bytes by task 13564 on cpu 0:
 __add_to_page_cache_locked+0x298/0x780 mm/filemap.c:890
 add_to_page_cache_lru+0xc4/0x260 mm/filemap.c:943
 mpage_readpages+0x263/0x3c0 fs/mpage.c:399
 blkdev_readpages+0x36/0x50 fs/block_dev.c:620
 read_pages+0xa2/0x2d0 mm/readahead.c:126
 __do_page_cache_readahead+0x353/0x390 mm/readahead.c:212
 force_page_cache_readahead+0x13a/0x1f0 mm/readahead.c:243
 page_cache_sync_readahead+0x1cf/0x1e0 mm/readahead.c:522
 generic_file_buffered_read mm/filemap.c:2051 [inline]
 generic_file_read_iter+0xeb6/0x1440 mm/filemap.c:2324
 blkdev_read_iter+0xb2/0xe0 fs/block_dev.c:2039
 call_read_iter include/linux/fs.h:1896 [inline]
 new_sync_read+0x389/0x4f0 fs/read_write.c:414
 __vfs_read+0xb1/0xc0 fs/read_write.c:427
 vfs_read fs/read_write.c:461 [inline]
 vfs_read+0x143/0x2c0 fs/read_write.c:446
 ksys_read+0xd5/0x1b0 fs/read_write.c:587
 __do_sys_read fs/read_write.c:597 [inline]
 __se_sys_read fs/read_write.c:595 [inline]
 __x64_sys_read+0x4c/0x60 fs/read_write.c:595
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812aba06e8 of 8 bytes by task 13493 on cpu 1:
 mapping_needs_writeback mm/filemap.c:632 [inline]
 filemap_write_and_wait+0x65/0x150 mm/filemap.c:639
 __sync_blockdev fs/block_dev.c:491 [inline]
 sync_blockdev fs/block_dev.c:500 [inline]
 set_blocksize+0x175/0x210 fs/block_dev.c:133
 sb_set_blocksize+0x3d/0xc0 fs/block_dev.c:145
 sb_min_blocksize+0xa5/0xc0 fs/block_dev.c:161
 ext4_fill_super+0x368/0x7a30 fs/ext4/super.c:3668
 mount_bdev+0x262/0x2d0 fs/super.c:1415
 ext4_mount+0x3e/0x60 fs/ext4/super.c:6026
 legacy_get_tree+0x7e/0xf0 fs/fs_context.c:647
 vfs_get_tree+0x56/0x1a0 fs/super.c:1545
 do_new_mount fs/namespace.c:2822 [inline]
 do_mount+0x1004/0x14f0 fs/namespace.c:3142
 ksys_mount+0xe8/0x160 fs/namespace.c:3351
 __do_sys_mount fs/namespace.c:3365 [inline]
 __se_sys_mount fs/namespace.c:3362 [inline]
 __x64_sys_mount+0x70/0x90 fs/namespace.c:3362
 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: 1 PID: 13493 Comm: syz-executor.2 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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