loop4: detected capacity change from 0 to 131456
==================================================================
BUG: KCSAN: data-race in data_push_tail / number

write to 0xffffffff86da28a4 of 1 bytes by task 17391 on cpu 1:
 number+0x846/0xb60 lib/vsprintf.c:556
 vsnprintf+0xb6d/0xed0 lib/vsprintf.c:2871
 vscnprintf+0x29/0x80 lib/vsprintf.c:2908
 printk_sprint kernel/printk/printk.c:2076 [inline]
 vprintk_store+0x638/0xbb0 kernel/printk/printk.c:2186
 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
 set_capacity_and_notify+0x17c/0x1e0 block/genhd.c:87
 loop_set_size drivers/block/loop.c:231 [inline]
 loop_configure+0xd30/0xf30 drivers/block/loop.c:1054
 lo_ioctl+0x583/0x1270
 blkdev_ioctl+0x20e/0x440 block/ioctl.c:609
 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 0xffffffff86da28a0 of 8 bytes by task 17393 on cpu 0:
 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
 set_capacity_and_notify+0x17c/0x1e0 block/genhd.c:87
 loop_set_size drivers/block/loop.c:231 [inline]
 loop_configure+0xd30/0xf30 drivers/block/loop.c:1054
 lo_ioctl+0x583/0x1270
 blkdev_ioctl+0x20e/0x440 block/ioctl.c:609
 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

value changed: 0x000000010000a19b -> 0x363534313331206f

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 17393 Comm: syz-executor.4 Not tainted 5.16.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
EXT4-fs (loop4): revision level too high, forcing read-only mode
EXT4-fs (loop4): mounted filesystem without journal. Opts: ,errors=continue. Quota mode: none.