syzbot

loop4: detected capacity change from 0 to 8
==================================================================
BUG: KCSAN: data-race in data_alloc / prb_reserve

write to 0xffffffff85a69898 of 8 bytes by task 5594 on cpu 0:
 data_alloc+0x27e/0x2b0 kernel/printk/printk_ringbuffer.c:1088
 prb_reserve+0x897/0xbd0 kernel/printk/printk_ringbuffer.c:1555
 vprintk_store+0x54d/0xb40 kernel/printk/printk.c:2199
 vprintk_emit+0xcc/0x430 kernel/printk/printk.c:2256
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2283
 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50
 _printk+0x76/0x96 kernel/printk/printk.c:2293
 __ext4_msg+0x16d/0x180 fs/ext4/super.c:944
 ext4_fill_super+0xa96/0x3a90 fs/ext4/super.c:5603
 get_tree_bdev+0x2b4/0x3b0 fs/super.c:1292
 vfs_get_tree+0x49/0x190 fs/super.c:1497
 do_new_mount+0x200/0x650 fs/namespace.c:3040
 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+0x44/0xae

read to 0xffffffff85a69898 of 8 bytes by task 5600 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:478 [inline]
 desc_push_tail kernel/printk/printk_ringbuffer.c:774 [inline]
 desc_reserve kernel/printk/printk_ringbuffer.c:920 [inline]
 prb_reserve+0x224/0xbd0 kernel/printk/printk_ringbuffer.c:1505
 vprintk_store+0x54d/0xb40 kernel/printk/printk.c:2199
 vprintk_emit+0xcc/0x430 kernel/printk/printk.c:2256
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2283
 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50
 _printk+0x76/0x96 kernel/printk/printk.c:2293
 __ext4_msg+0x16d/0x180 fs/ext4/super.c:944
 ext4_fill_super+0xa96/0x3a90 fs/ext4/super.c:5603
 get_tree_bdev+0x2b4/0x3b0 fs/super.c:1292
 vfs_get_tree+0x49/0x190 fs/super.c:1497
 do_new_mount+0x200/0x650 fs/namespace.c:3040
 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+0x44/0xae

value changed: 0x00000000002005d0 -> 0x0000000000284bb8

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 5600 Comm: syz-executor.4 Not tainted 5.18.0-rc7-syzkaller-00119-gb015dcd62b86-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
EXT4-fs (loop4): Invalid log cluster size: 38