syzbot

[EXT4 FS bs=1024, gc=1, bpg=8192, ipg=32, mo=a002c01c, mo2=0006]
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BUG: KCSAN: data-race in data_push_tail / number

write to 0xffffffff86d8ec46 of 1 bytes by task 20201 on cpu 0:
 number+0x8ca/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
 ext4_setup_super+0x399/0x3a0 fs/ext4/super.c:2708
 ext4_fill_super+0x4023/0x5870 fs/ext4/super.c:4842
 mount_bdev+0x1e8/0x290 fs/super.c:1370
 legacy_get_tree+0x70/0xc0 fs/fs_context.c:610
 vfs_get_tree+0x4a/0x1a0 fs/super.c:1500
 do_new_mount fs/namespace.c:2988 [inline]
 path_mount+0x11cf/0x1c40 fs/namespace.c:3318
 do_mount fs/namespace.c:3331 [inline]
 __do_sys_mount fs/namespace.c:3539 [inline]
 __se_sys_mount+0x24b/0x2f0 fs/namespace.c:3516
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3516
 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 0xffffffff86d8ec40 of 8 bytes by task 20206 on cpu 1:
 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
 ext4_setup_super+0x399/0x3a0 fs/ext4/super.c:2708
 ext4_fill_super+0x4023/0x5870 fs/ext4/super.c:4842
 mount_bdev+0x1e8/0x290 fs/super.c:1370
 legacy_get_tree+0x70/0xc0 fs/fs_context.c:610
 vfs_get_tree+0x4a/0x1a0 fs/super.c:1500
 do_new_mount fs/namespace.c:2988 [inline]
 path_mount+0x11cf/0x1c40 fs/namespace.c:3318
 do_mount fs/namespace.c:3331 [inline]
 __do_sys_mount fs/namespace.c:3539 [inline]
 __se_sys_mount+0x24b/0x2f0 fs/namespace.c:3516
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3516
 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: 0x0000000100015421 -> 0x323931383d677062

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 20206 Comm: syz-executor.4 Tainted: G        W         5.16.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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System zones: 1-2, 19-19, 35-38, 46-46