loop1: detected capacity change from 0 to 256
==================================================================
BUG: KCSAN: data-race in data_alloc / data_push_tail

write to 0xffffffff86e7d930 of 8 bytes by task 8543 on cpu 1:
 data_alloc+0x205/0x2b0 kernel/printk/printk_ringbuffer.c:1074
 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
 logfc+0x2bb/0x2d0
 vfs_parse_fs_param+0x1cf/0x290 fs/fs_context.c:158
 vfs_parse_fs_string fs/fs_context.c:184 [inline]
 generic_parse_monolithic+0x16d/0x1d0 fs/fs_context.c:224
 nfs_fs_context_parse_monolithic+0x403/0x10e0
 parse_monolithic_mount_data+0x3e/0x50 fs/fs_context.c:667
 do_new_mount+0x1d3/0x650 fs/namespace.c:3036
 path_mount+0x4b1/0xb60 fs/namespace.c:3370
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount+0x281/0x2d0 fs/namespace.c:3568
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3568
 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 0xffffffff86e7d930 of 8 bytes by task 8542 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+0x170/0x1d0 block/genhd.c:90
 loop_set_size+0x2e/0x70 drivers/block/loop.c:237
 loop_configure+0xb1b/0xc20 drivers/block/loop.c:1095
 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: 0x00000000ffffea82 -> 0x00000000fffffc7c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8542 Comm: syz-executor.1 Not tainted 5.19.0-rc6-syzkaller-00272-ge5d523f1ae8f-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
==================================================================
nfs: Unknown parameter 'gre0'
syz-executor.1 (8542) used greatest stack depth: 11088 bytes left