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BUG: KCSAN: data-race in blk_mq_get_request / blk_mq_get_request

write to 0xffff888129997548 of 8 bytes by task 7473 on cpu 1:
 blk_mq_get_request+0x8e1/0xb50 block/blk-mq.c:418
 blk_mq_make_request+0x2d9/0xf60 block/blk-mq.c:1974
 generic_make_request block/blk-core.c:1064 [inline]
 generic_make_request+0x196/0x740 block/blk-core.c:1006
 submit_bio+0x96/0x3c0 block/blk-core.c:1190
 dio_bio_submit fs/direct-io.c:481 [inline]
 do_blockdev_direct_IO+0x64e1/0x78c0 fs/direct-io.c:1353
 __blockdev_direct_IO+0x86/0xa0 fs/direct-io.c:1412
 ext4_direct_IO_write fs/ext4/inode.c:3742 [inline]
 ext4_direct_IO+0x6f5/0xf70 fs/ext4/inode.c:3871
 generic_file_direct_write+0x14d/0x2e0 mm/filemap.c:3207
 __generic_file_write_iter+0x17e/0x380 mm/filemap.c:3390
 ext4_file_write_iter+0x1bd/0xa00 fs/ext4/file.c:268
 call_write_iter include/linux/fs.h:1895 [inline]
 do_iter_readv_writev+0x487/0x5b0 fs/read_write.c:693
 do_iter_write fs/read_write.c:970 [inline]
 do_iter_write+0x13b/0x3c0 fs/read_write.c:951
 vfs_iter_write+0x5c/0x80 fs/read_write.c:983
 iter_file_splice_write+0x4c0/0x7f0 fs/splice.c:746

read to 0xffff888129997548 of 8 bytes by task 7479 on cpu 0:
 blk_mq_get_request+0x8ce/0xb50 block/blk-mq.c:418
 blk_mq_make_request+0x2d9/0xf60 block/blk-mq.c:1974
 generic_make_request block/blk-core.c:1064 [inline]
 generic_make_request+0x196/0x740 block/blk-core.c:1006
 submit_bio+0x96/0x3c0 block/blk-core.c:1190
 ext4_mpage_readpages+0xb1d/0x12c0 fs/ext4/readpage.c:408
 ext4_readpages+0x92/0xc0 fs/ext4/inode.c:3342
 read_pages+0xa2/0x2d0 mm/readahead.c:126
 __do_page_cache_readahead+0x353/0x390 mm/readahead.c:212
 ra_submit mm/internal.h:62 [inline]
 ondemand_readahead+0x35d/0x710 mm/readahead.c:492
 page_cache_sync_readahead+0x1ad/0x1e0 mm/readahead.c:527
 generic_file_buffered_read mm/filemap.c:2050 [inline]
 generic_file_read_iter+0xeb6/0x1440 mm/filemap.c:2323
 ext4_file_read_iter fs/ext4/file.c:77 [inline]
 ext4_file_read_iter+0xfa/0x240 fs/ext4/file.c:65
 call_read_iter include/linux/fs.h:1889 [inline]
 generic_file_splice_read+0x35c/0x500 fs/splice.c:307

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7479 Comm: syz-executor.2 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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