syzbot

loop7: detected capacity change from 0 to 1024
EXT4-fs: Ignoring removed bh option
EXT4-fs: inline encryption not supported
==================================================================
BUG: KCSAN: data-race in data_push_tail / vsnprintf

write to 0xffffffff88e48208 of 4 bytes by task 11575 on cpu 0:
 vsnprintf+0x2ce/0x890 lib/vsprintf.c:2826
 vscnprintf+0x41/0x90 lib/vsprintf.c:2939
 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2216
 vprintk_store+0x599/0x860 kernel/printk/printk.c:2336
 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2475
 set_capacity_and_notify+0x14c/0x1f0 block/genhd.c:93
 loop_set_size+0x2e/0x70 drivers/block/loop.c:210
 loop_configure+0x8d3/0xa50 drivers/block/loop.c:1064
 lo_ioctl+0x559/0x15d0 drivers/block/loop.c:-1
 blkdev_ioctl+0x352/0x440 block/ioctl.c:704
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:893
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:893
 x64_sys_call+0x19a8/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff88e48208 of 8 bytes by task 11574 on cpu 1:
 data_make_reusable kernel/printk/printk_ringbuffer.c:594 [inline]
 data_push_tail+0xfd/0x420 kernel/printk/printk_ringbuffer.c:679
 data_alloc+0xbf/0x2b0 kernel/printk/printk_ringbuffer.c:1054
 prb_reserve+0x808/0xaf0 kernel/printk/printk_ringbuffer.c:1669
 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2326
 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2475
 __ext4_msg+0x135/0x1a0 fs/ext4/super.c:983
 ext4_parse_param+0x252/0xf10 fs/ext4/super.c:2180
 vfs_parse_fs_param+0x142/0x2a0 fs/fs_context.c:146
 vfs_parse_fs_string fs/fs_context.c:188 [inline]
 vfs_parse_monolithic_sep+0x18a/0x200 fs/fs_context.c:230
 generic_parse_monolithic+0x24/0x30 fs/fs_context.c:258
 parse_monolithic_mount_data+0x43/0x60 fs/fs_context.c:723
 do_new_mount+0x1da/0x680 fs/namespace.c:3878
 path_mount+0x4a4/0xb20 fs/namespace.c:4209
 do_mount fs/namespace.c:4222 [inline]
 __do_sys_mount fs/namespace.c:4433 [inline]
 __se_sys_mount+0x28f/0x2e0 fs/namespace.c:4410
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4410
 x64_sys_call+0xd36/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000fffff212 -> 0x0a3231323135206f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 11574 Comm: syz.7.2283 Not tainted 6.15.0-syzkaller-08486-gf66bc387efbe #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================
EXT4-fs (loop7): stripe (65535) is not aligned with cluster size (4096), stripe is disabled
workqueue: Failed to create a rescuer kthread for wq "ext4-rsv-conversion": -EINTR
EXT4-fs: failed to create workqueue
EXT4-fs (loop7): mount failed