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BUG: KCSAN: data-race in blk_mq_get_request / blk_mq_get_request

write to 0xffff888129b57148 of 8 bytes by task 15328 on cpu 1:
 blk_mq_get_request+0x91a/0xba0 block/blk-mq.c:396
 blk_mq_make_request+0x2d7/0xf60 block/blk-mq.c:2001
 generic_make_request block/blk-core.c:1075 [inline]
 generic_make_request+0x196/0x700 block/blk-core.c:1017
 submit_bio+0x8f/0x3a0 block/blk-core.c:1200
 submit_bh_wbc+0x40d/0x460 fs/buffer.c:3063
 submit_bh fs/buffer.c:3069 [inline]
 __sync_dirty_buffer+0xd9/0x210 fs/buffer.c:3155
 sync_dirty_buffer+0x21/0x30 fs/buffer.c:3168
 __ext4_handle_dirty_metadata+0x1b5/0x3d0 fs/ext4/ext4_jbd2.c:339
 ext4_handle_dirty_dirblock+0x206/0x270 fs/ext4/namei.c:411
 add_dirent_to_buf+0x271/0x3d0 fs/ext4/namei.c:2033
 ext4_add_entry+0x37c/0x970 fs/ext4/namei.c:2241
 ext4_add_nondir+0x59/0x170 fs/ext4/namei.c:2577
 ext4_symlink+0x63e/0x9e0 fs/ext4/namei.c:3364
 vfs_symlink fs/namei.c:3937 [inline]
 vfs_symlink+0x216/0x330 fs/namei.c:3923
 do_symlinkat+0x1ac/0x1e0 fs/namei.c:3964
 __do_sys_symlink fs/namei.c:3983 [inline]
 __se_sys_symlink fs/namei.c:3981 [inline]
 __x64_sys_symlink+0x3c/0x50 fs/namei.c:3981
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888129b57148 of 8 bytes by task 9304 on cpu 0:
 blk_mq_get_request+0x907/0xba0 block/blk-mq.c:396
 blk_mq_make_request+0x2d7/0xf60 block/blk-mq.c:2001
 generic_make_request block/blk-core.c:1075 [inline]
 generic_make_request+0x196/0x700 block/blk-core.c:1017
 submit_bio+0x8f/0x3a0 block/blk-core.c:1200
 submit_bh_wbc+0x40d/0x460 fs/buffer.c:3063
 submit_bh fs/buffer.c:3069 [inline]
 __sync_dirty_buffer+0xd9/0x210 fs/buffer.c:3155
 sync_dirty_buffer+0x21/0x30 fs/buffer.c:3168
 __ext4_handle_dirty_metadata+0x1b5/0x3d0 fs/ext4/ext4_jbd2.c:339
 ext4_getblk+0x241/0x380 fs/ext4/inode.c:859
 ext4_bread+0x47/0x200 fs/ext4/inode.c:875
 ext4_append+0xc0/0x1e0 fs/ext4/namei.c:67
 ext4_init_new_dir fs/ext4/namei.c:2755 [inline]
 ext4_mkdir+0x400/0x850 fs/ext4/namei.c:2800
 vfs_mkdir+0x281/0x3b0 fs/namei.c:3625
 do_mkdirat+0x1b5/0x200 fs/namei.c:3648
 __do_sys_mkdir fs/namei.c:3664 [inline]
 __se_sys_mkdir fs/namei.c:3662 [inline]
 __x64_sys_mkdir+0x3d/0x50 fs/namei.c:3662
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 9304 Comm: syz-executor.4 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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