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BUG: KCSAN: data-race in blk_mq_get_request / blk_mq_get_request

write to 0xffff888129920d48 of 8 bytes by task 8131 on cpu 0:
 blk_mq_get_request+0x897/0xaf0 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
 mpage_bio_submit fs/mpage.c:66 [inline]
 mpage_readpages+0x36c/0x3c0 fs/mpage.c:410
 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
 ra_submit mm/internal.h:62 [inline]
 do_sync_mmap_readahead mm/filemap.c:2443 [inline]
 filemap_fault+0xdad/0xf90 mm/filemap.c:2529
 __do_fault+0xae/0x1f0 mm/memory.c:3092
 do_shared_fault mm/memory.c:3544 [inline]
 do_fault mm/memory.c:3622 [inline]
 handle_pte_fault mm/memory.c:3849 [inline]
 __handle_mm_fault+0x2019/0x2c70 mm/memory.c:3973
 handle_mm_fault+0x21b/0x530 mm/memory.c:4010
 do_user_addr_fault arch/x86/mm/fault.c:1441 [inline]
 __do_page_fault+0x456/0x8d0 arch/x86/mm/fault.c:1506
 do_page_fault+0x38/0x194 arch/x86/mm/fault.c:1530
 page_fault+0x34/0x40 arch/x86/entry/entry_64.S:1202
 copy_user_enhanced_fast_string+0xe/0x30 arch/x86/lib/copy_user_64.S:204
 copy_page_to_iter_iovec lib/iov_iter.c:211 [inline]
 copy_page_to_iter+0x254/0x8b0 lib/iov_iter.c:900
 generic_file_buffered_read mm/filemap.c:2144 [inline]
 generic_file_read_iter+0x978/0x1440 mm/filemap.c:2324
 blkdev_read_iter+0xb2/0xe0 fs/block_dev.c:2010
 call_read_iter include/linux/fs.h:1889 [inline]
 do_iter_readv_writev+0x54b/0x5b0 fs/read_write.c:691
 do_iter_read+0x1fc/0x3d0 fs/read_write.c:933
 vfs_readv+0x9c/0xf0 fs/read_write.c:997
 do_preadv+0x131/0x1d0 fs/read_write.c:1089
 __do_sys_preadv fs/read_write.c:1139 [inline]
 __se_sys_preadv fs/read_write.c:1134 [inline]
 __x64_sys_preadv+0x61/0x80 fs/read_write.c:1134
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888129920d48 of 8 bytes by task 8137 on cpu 1:
 blk_mq_get_request+0x884/0xaf0 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
 mpage_bio_submit fs/mpage.c:66 [inline]
 mpage_readpages+0x36c/0x3c0 fs/mpage.c:410
 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:2010
 call_read_iter include/linux/fs.h:1889 [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/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8137 Comm: blkid Not tainted 5.4.0-rc7+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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