loop1: detected capacity change from 0 to 264192
 loop1: p1 < > p3 < >
==================================================================
BUG: KCSAN: data-race in data_push_tail / string

write to 0xffffffff86e7c1e8 of 1 bytes by task 13755 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
 check_partition block/partitions/core.c:159 [inline]
 blk_add_partitions block/partitions/core.c:600 [inline]
 bdev_disk_changed+0x9dd/0xc30 block/partitions/core.c:686
 loop_reread_partitions drivers/block/loop.c:518 [inline]
 loop_set_status+0x44f/0x4f0 drivers/block/loop.c:1317
 lo_ioctl+0x83e/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 0xffffffff86e7c1e8 of 8 bytes by task 13756 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
 check_partition block/partitions/core.c:159 [inline]
 blk_add_partitions block/partitions/core.c:600 [inline]
 bdev_disk_changed+0x9dd/0xc30 block/partitions/core.c:686
 loop_reread_partitions drivers/block/loop.c:518 [inline]
 loop_set_status+0x44f/0x4f0 drivers/block/loop.c:1317
 lo_ioctl+0x83e/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: 0x00000000fffff615 -> 0x70203e203c203170

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 13756 Comm: syz-executor.1 Not tainted 5.19.0-rc8-syzkaller-00146-ge65c6a46df94-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
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