==================================================================
BUG: KCSAN: data-race in data_alloc / data_push_tail

write to 0xffffffff86db83b0 of 8 bytes by task 6270 on cpu 0:
 data_alloc+0x205/0x2b0 kernel/printk/printk_ringbuffer.c:1071
 prb_reserve+0x920/0xbf0 kernel/printk/printk_ringbuffer.c:1549
 vprintk_store+0x560/0xbb0 kernel/printk/printk.c:2176
 vprintk_emit+0xac/0x3c0 kernel/printk/printk.c:2229
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2256
 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50
 _printk+0x76/0x97 kernel/printk/printk.c:2266
 fail_dump lib/fault-inject.c:45 [inline]
 should_fail+0x223/0x250 lib/fault-inject.c:146
 __should_failslab+0x81/0x90 mm/failslab.c:33
 should_failslab+0x5/0x20 mm/slab_common.c:1304
 slab_pre_alloc_hook mm/slab.h:707 [inline]
 slab_alloc mm/slab.c:3298 [inline]
 kmem_cache_alloc_trace+0x52/0x350 mm/slab.c:3565
 kmalloc include/linux/slab.h:581 [inline]
 kzalloc include/linux/slab.h:714 [inline]
 alloc_workqueue_attrs kernel/workqueue.c:3405 [inline]
 alloc_workqueue+0x15d/0xad0 kernel/workqueue.c:4330
 loop_configure+0x72f/0xf50 drivers/block/loop.c:1015
 lo_ioctl+0x633/0x1260
 blkdev_ioctl+0x20e/0x440 block/ioctl.c:588
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:860
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffffff86db83b0 of 8 bytes by task 6263 on cpu 1:
 data_make_reusable kernel/printk/printk_ringbuffer.c:587 [inline]
 data_push_tail+0x138/0x470 kernel/printk/printk_ringbuffer.c:672
 data_alloc+0xbc/0x2b0 kernel/printk/printk_ringbuffer.c:1043
 prb_reserve+0x920/0xbf0 kernel/printk/printk_ringbuffer.c:1549
 vprintk_store+0x560/0xbb0 kernel/printk/printk.c:2176
 vprintk_emit+0xac/0x3c0 kernel/printk/printk.c:2229
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2256
 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50
 _printk+0x76/0x97 kernel/printk/printk.c:2266
 __ext4_error_inode+0x225/0x310 fs/ext4/super.c:807
 __ext4_iget+0x3be/0x1c30
 __ext4_fill_super+0x3fee/0x59b0 fs/ext4/super.c:5277
 ext4_fill_super+0x10b/0x2f0 fs/ext4/super.c:5554
 get_tree_bdev+0x2c2/0x3d0 fs/super.c:1292
 vfs_get_tree+0x4a/0x1a0 fs/super.c:1497
 do_new_mount fs/namespace.c:3024 [inline]
 path_mount+0x11cf/0x1c40 fs/namespace.c:3354
 do_mount fs/namespace.c:3367 [inline]
 __do_sys_mount fs/namespace.c:3575 [inline]
 __se_sys_mount+0x24b/0x2f0 fs/namespace.c:3552
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3552
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000000ffffe6c2 -> 0x00000000fffff4e4

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 6263 Comm: syz-executor.4 Not tainted 5.17.0-rc7-syzkaller-00060-g92f90cc9fe0e-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
EXT4-fs (loop4): get root inode failed
EXT4-fs (loop4): mount failed