==================================================================
BUG: KCSAN: data-race in blk_mq_get_request / blk_mq_get_request

write to 0xffff8881299f1148 of 8 bytes by task 26971 on cpu 0:
 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
 submit_bh_wbc+0x40f/0x460 fs/buffer.c:3095
 submit_bh fs/buffer.c:3101 [inline]
 __sync_dirty_buffer+0xd3/0x210 fs/buffer.c:3187
 sync_dirty_buffer+0x24/0x40 fs/buffer.c:3200
 __ext4_handle_dirty_metadata+0x19c/0x350 fs/ext4/ext4_jbd2.c:300
 ext4_getblk+0x24a/0x380 fs/ext4/inode.c:1008
 ext4_bread+0x4a/0x210 fs/ext4/inode.c:1024
 ext4_append+0xc8/0x1f0 fs/ext4/namei.c:67
 ext4_init_new_dir fs/ext4/namei.c:2728 [inline]
 ext4_mkdir+0x421/0x820 fs/ext4/namei.c:2773
 vfs_mkdir+0x283/0x390 fs/namei.c:3807
 do_mkdirat+0x1ac/0x1f0 fs/namei.c:3830

read to 0xffff8881299f1148 of 8 bytes by task 26907 on cpu 1:
 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
 submit_bh_wbc+0x40f/0x460 fs/buffer.c:3095
 submit_bh fs/buffer.c:3101 [inline]
 __sync_dirty_buffer+0xd3/0x210 fs/buffer.c:3187
 sync_dirty_buffer+0x24/0x40 fs/buffer.c:3200
 __ext4_handle_dirty_metadata+0x19c/0x350 fs/ext4/ext4_jbd2.c:300
 ext4_handle_dirty_dirblock+0x20a/0x280 fs/ext4/namei.c:404
 ext4_delete_entry+0x266/0x2c0 fs/ext4/namei.c:2509
 ext4_unlink fs/ext4/namei.c:3190 [inline]
 ext4_unlink+0x33f/0x7d0 fs/ext4/namei.c:3140
 vfs_unlink+0x225/0x3e0 fs/namei.c:3991
 do_unlinkat+0x32b/0x530 fs/namei.c:4055

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 26907 Comm: syz-executor.3 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================