loop1: detected capacity change from 0 to 4
==================================================================
BUG: KCSAN: data-race in data_push_tail / number

write to 0xffffffff8412f927 of 1 bytes by task 969 on cpu 0:
 number+0x836/0xb50 lib/vsprintf.c:556
 vsnprintf+0xb6d/0xed0 lib/vsprintf.c:2863
 vscnprintf+0x29/0x80 lib/vsprintf.c:2900
 printk_sprint kernel/printk/printk.c:2075 [inline]
 vprintk_store+0x5c2/0xb10 kernel/printk/printk.c:2185
 vprintk_emit+0xac/0x380 kernel/printk/printk.c:2228
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2255
 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50
 _printk+0x62/0x87 kernel/printk/printk.c:2265
 set_capacity_and_notify+0x19e/0x200 block/genhd.c:84
 loop_set_size drivers/block/loop.c:298 [inline]
 loop_configure+0xcaa/0xeb0 drivers/block/loop.c:1297
 lo_ioctl+0x59b/0x1370 drivers/block/loop.c:1845
 blkdev_ioctl+0x1d0/0x3e0 block/ioctl.c:589
 block_ioctl+0x6d/0x80 fs/block_dev.c:1421
 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+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffffff8412f920 of 8 bytes by task 1000 on cpu 1:
 data_make_reusable kernel/printk/printk_ringbuffer.c:587 [inline]
 data_push_tail+0x125/0x460 kernel/printk/printk_ringbuffer.c:672
 data_alloc+0xbc/0x2b0 kernel/printk/printk_ringbuffer.c:1043
 prb_reserve+0x8f0/0xbc0 kernel/printk/printk_ringbuffer.c:1549
 vprintk_store+0x4ef/0xb10 kernel/printk/printk.c:2175
 vprintk_emit+0xac/0x380 kernel/printk/printk.c:2228
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2255
 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50
 _printk+0x62/0x87 kernel/printk/printk.c:2265
 set_capacity_and_notify+0x19e/0x200 block/genhd.c:84
 loop_set_size drivers/block/loop.c:298 [inline]
 loop_configure+0xcaa/0xeb0 drivers/block/loop.c:1297
 lo_ioctl+0x59b/0x1370 drivers/block/loop.c:1845
 blkdev_ioctl+0x1d0/0x3e0 block/ioctl.c:589
 block_ioctl+0x6d/0x80 fs/block_dev.c:1421
 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+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000100003ae4 -> 0x742030206d6f7266

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1000 Comm: syz-executor.1 Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
EXT4-fs (loop1): Quota format mount options ignored when QUOTA feature is enabled
EXT4-fs (loop1): #blocks per group too big: 4261429248