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BUG: KCSAN: data-race in data_push_tail / number

write to 0xffffffff841548fb of 1 bytes by task 23856 on cpu 0:
 number+0x836/0xb50 lib/vsprintf.c:556
 vsnprintf+0xb6d/0xed0 lib/vsprintf.c:2863
 va_format lib/vsprintf.c:1694 [inline]
 pointer+0x47b/0x820 lib/vsprintf.c:2427
 vsnprintf+0x8a1/0xed0 lib/vsprintf.c:2801
 vscnprintf+0x29/0x80 lib/vsprintf.c:2900
 printk_sprint kernel/printk/printk.c:2012 [inline]
 vprintk_store+0x4c1/0x9c0 kernel/printk/printk.c:2115
 vprintk_emit+0xca/0x3d0 kernel/printk/printk.c:2157
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2185
 vprintk+0x15a/0x170 kernel/printk/printk_safe.c:392
 printk+0x62/0x87 kernel/printk/printk.c:2216
 __ext4_msg+0x103/0x110 fs/ext4/super.c:917
 ext4_fill_super+0x2e86/0x7ff0 fs/ext4/super.c:4631
 mount_bdev+0x1e8/0x290 fs/super.c:1368
 ext4_mount+0x2d/0x40 fs/ext4/super.c:6638
 legacy_get_tree+0x70/0xc0 fs/fs_context.c:610
 vfs_get_tree+0x4a/0x1a0 fs/super.c:1498
 do_new_mount fs/namespace.c:2923 [inline]
 path_mount+0x11f2/0x1d30 fs/namespace.c:3253
 do_mount fs/namespace.c:3266 [inline]
 __do_sys_mount fs/namespace.c:3474 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3451
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3451
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffffff841548f8 of 8 bytes by task 23870 on cpu 1:
 data_make_reusable kernel/printk/printk_ringbuffer.c:587 [inline]
 data_push_tail+0x125/0x460 kernel/printk/printk_ringbuffer.c:672
 data_alloc+0xbc/0x2b0 kernel/printk/printk_ringbuffer.c:1043
 prb_reserve+0x8f0/0xbc0 kernel/printk/printk_ringbuffer.c:1549
 vprintk_store+0x3e9/0x9c0 kernel/printk/printk.c:2105
 vprintk_emit+0xca/0x3d0 kernel/printk/printk.c:2157
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2185
 vprintk+0x15a/0x170 kernel/printk/printk_safe.c:392
 printk+0x62/0x87 kernel/printk/printk.c:2216
 __nla_validate_parse+0x148e/0x17f0 lib/nlattr.c:600
 __nla_parse+0x3c/0x50 lib/nlattr.c:685
 nla_parse_deprecated include/net/netlink.h:680 [inline]
 nfnetlink_rcv_msg+0x35c/0x550 net/netfilter/nfnetlink.c:270
 netlink_rcv_skb+0x13e/0x240 net/netlink/af_netlink.c:2504
 nfnetlink_rcv+0x161/0x1340 net/netfilter/nfnetlink.c:654
 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
 netlink_unicast+0x5ec/0x6b0 net/netlink/af_netlink.c:1340
 netlink_sendmsg+0x6d9/0x7c0 net/netlink/af_netlink.c:1929
 sock_sendmsg_nosec net/socket.c:703 [inline]
 sock_sendmsg net/socket.c:723 [inline]
 sock_write_iter+0x1a4/0x200 net/socket.c:1056
 call_write_iter include/linux/fs.h:2114 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x69d/0x770 fs/read_write.c:605
 ksys_write+0xce/0x180 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:667
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000000ffffe4cd -> 0x00000000ff203a64

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 23870 Comm: syz-executor.1 Tainted: G        W         5.14.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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