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BUG: KCSAN: data-race in wbt_inflight_cb / wbt_wait

write to 0xffff888102853240 of 8 bytes by task 28035 on cpu 0:
 wb_timestamp block/blk-wbt.c:89 [inline]
 wbt_wait+0x12b/0x2b0 block/blk-wbt.c:579
 __rq_qos_throttle+0x39/0x70 block/blk-rq-qos.c:72
 rq_qos_throttle block/blk-rq-qos.h:182 [inline]
 blk_mq_submit_bio+0x240/0x1040 block/blk-mq.c:2158
 __submit_bio_noacct_mq block/blk-core.c:1028 [inline]
 submit_bio_noacct+0x78d/0x960 block/blk-core.c:1061
 submit_bio+0x200/0x360 block/blk-core.c:1131
 mpage_bio_submit fs/mpage.c:66 [inline]
 mpage_readahead+0x2ef/0x330 fs/mpage.c:395
 blkdev_readahead+0x18/0x20 fs/block_dev.c:636
 read_pages+0x9c/0x6e0 mm/readahead.c:130
 page_cache_ra_unbounded+0x17d/0x4c0 mm/readahead.c:212
 do_page_cache_ra mm/readahead.c:267 [inline]
 force_page_cache_ra+0x226/0x260 mm/readahead.c:298
 page_cache_sync_ra+0x178/0x1a0 mm/readahead.c:572
 page_cache_sync_readahead include/linux/pagemap.h:839 [inline]
 generic_file_buffered_read_get_pages+0x234/0xaf0 mm/filemap.c:2365
 generic_file_buffered_read+0x26e/0x9c0 mm/filemap.c:2485
 generic_file_read_iter+0x82/0x3e0 mm/filemap.c:2637
 blkdev_read_iter+0xb3/0xc0 fs/block_dev.c:1714
 call_read_iter include/linux/fs.h:1895 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 vfs_read+0x565/0x5d0 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 0xffff888102853240 of 8 bytes by task 28025 on cpu 1:
 close_io block/blk-wbt.c:444 [inline]
 get_limit block/blk-wbt.c:474 [inline]
 wbt_inflight_cb+0x19a/0x220 block/blk-wbt.c:495
 rq_qos_wait+0xac/0x220 block/blk-rq-qos.c:266
 __wbt_wait block/blk-wbt.c:518 [inline]
 wbt_wait+0x1bb/0x2b0 block/blk-wbt.c:583
 __rq_qos_throttle+0x39/0x70 block/blk-rq-qos.c:72
 rq_qos_throttle block/blk-rq-qos.h:182 [inline]
 blk_mq_submit_bio+0x240/0x1040 block/blk-mq.c:2158
 __submit_bio_noacct_mq block/blk-core.c:1028 [inline]
 submit_bio_noacct+0x78d/0x960 block/blk-core.c:1061
 submit_bio+0x200/0x360 block/blk-core.c:1131
 submit_bh_wbc+0x39d/0x3e0 fs/buffer.c:3054
 __block_write_full_page+0x618/0x9e0 fs/buffer.c:1810
 block_write_full_page+0x260/0x290 fs/buffer.c:2980
 fat_writepage+0x20/0x30 fs/fat/inode.c:199
 writeout mm/migrate.c:890 [inline]
 fallback_migrate_page mm/migrate.c:914 [inline]
 move_to_new_page+0x305/0x6c0 mm/migrate.c:965
 __unmap_and_move+0x432/0x690 mm/migrate.c:1127
 unmap_and_move+0x131/0x690 mm/migrate.c:1194
 migrate_pages+0x2f7/0xfa0 mm/migrate.c:1466
 do_mbind+0xe47/0x1030 mm/mempolicy.c:1347
 kernel_mbind mm/mempolicy.c:1468 [inline]
 __do_sys_mbind mm/mempolicy.c:1475 [inline]
 __se_sys_mbind mm/mempolicy.c:1471 [inline]
 __x64_sys_mbind+0x142/0x170 mm/mempolicy.c:1471
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 28025 Comm: syz-executor.5 Not tainted 5.11.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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