loop0: detected capacity change from 0 to 8
==================================================================
BUG: KCSAN: data-race in data_push_tail / string

write to 0xffffffff8708109a of 1 bytes by task 17584 on cpu 1:
 string_nocheck lib/vsprintf.c:647 [inline]
 string+0x17b/0x220 lib/vsprintf.c:725
 vsnprintf+0xb57/0xe80 lib/vsprintf.c:2782
 vscnprintf+0x3e/0x80 lib/vsprintf.c:2888
 printk_sprint kernel/printk/printk.c:2092 [inline]
 vprintk_store+0x5f2/0xb50 kernel/printk/printk.c:2206
 vprintk_emit+0xcc/0x430 kernel/printk/printk.c:2252
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2282
 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50
 _printk+0x76/0x96 kernel/printk/printk.c:2292
 set_capacity_and_notify+0x176/0x1d0 block/genhd.c:90
 loop_set_size+0x2e/0x70 drivers/block/loop.c:237
 loop_configure+0xb1b/0xc30 drivers/block/loop.c:1100
 lo_ioctl+0x641/0x1290
 blkdev_ioctl+0x20e/0x440 block/ioctl.c:614
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:856
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffffffff87081098 of 8 bytes by task 17586 on cpu 0:
 data_make_reusable kernel/printk/printk_ringbuffer.c:590 [inline]
 data_push_tail+0x10f/0x440 kernel/printk/printk_ringbuffer.c:675
 data_alloc+0xbc/0x2b0 kernel/printk/printk_ringbuffer.c:1046
 prb_reserve+0x897/0xbd0 kernel/printk/printk_ringbuffer.c:1555
 vprintk_store+0x51c/0xb50 kernel/printk/printk.c:2196
 vprintk_emit+0xcc/0x430 kernel/printk/printk.c:2252
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2282
 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50
 _printk+0x76/0x96 kernel/printk/printk.c:2292
 set_capacity_and_notify+0x176/0x1d0 block/genhd.c:90
 loop_set_size+0x2e/0x70 drivers/block/loop.c:237
 loop_configure+0xb1b/0xc30 drivers/block/loop.c:1100
 lo_ioctl+0x641/0x1290
 blkdev_ioctl+0x20e/0x440 block/ioctl.c:614
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:856
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000000ffffe276 -> 0x64203a32706f6f6c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 17586 Comm: syz-executor.0 Not tainted 6.0.0-rc7-syzkaller-00250-ga962b54e162c-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
==================================================================
syz-executor.0 (17586) used greatest stack depth: 11152 bytes left