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BUG: KCSAN: data-race in data_alloc / prb_reserve

write to 0xffffffff86672318 of 8 bytes by task 31468 on cpu 1:
 data_alloc+0x291/0x2c0 kernel/printk/printk_ringbuffer.c:1096
 prb_reserve+0x85e/0xb60 kernel/printk/printk_ringbuffer.c:1669
 vprintk_store+0x558/0x870 kernel/printk/printk.c:2326
 vprintk_emit+0x15e/0x680 kernel/printk/printk.c:2408
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2447
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:86
 _printk+0x7a/0xa0 kernel/printk/printk.c:2457
 __ext4_warning+0x130/0x140 fs/ext4/super.c:1023
 ext4_update_dynamic_rev+0x7b/0xc0 fs/ext4/super.c:1142
 ext4_set_feature_large_file fs/ext4/ext4.h:2124 [inline]
 ext4_do_update_inode fs/ext4/inode.c:5174 [inline]
 ext4_mark_iloc_dirty+0xba4/0xe10 fs/ext4/inode.c:5808
 __ext4_mark_inode_dirty+0x314/0x440 fs/ext4/inode.c:6012
 ext4_ext_truncate+0x58/0x150 fs/ext4/extents.c:4457
 ext4_truncate+0x776/0xb10 fs/ext4/inode.c:4217
 ext4_process_orphan+0x113/0x1c0 fs/ext4/orphan.c:339
 ext4_orphan_cleanup+0x696/0x9e0 fs/ext4/orphan.c:474
 __ext4_fill_super fs/ext4/super.c:5610 [inline]
 ext4_fill_super+0x36bb/0x3a10 fs/ext4/super.c:5733
 get_tree_bdev_flags+0x29f/0x310 fs/super.c:1636
 get_tree_bdev+0x1f/0x30 fs/super.c:1659
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5765
 vfs_get_tree+0x56/0x1e0 fs/super.c:1814
 do_new_mount+0x227/0x690 fs/namespace.c:3507
 path_mount+0x49b/0xb30 fs/namespace.c:3834
 do_mount fs/namespace.c:3847 [inline]
 __do_sys_mount fs/namespace.c:4057 [inline]
 __se_sys_mount+0x27c/0x2d0 fs/namespace.c:4034
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4034
 x64_sys_call+0x2c84/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff86672318 of 8 bytes by task 31470 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:482 [inline]
 desc_push_tail kernel/printk/printk_ringbuffer.c:778 [inline]
 desc_reserve kernel/printk/printk_ringbuffer.c:924 [inline]
 prb_reserve+0x235/0xb60 kernel/printk/printk_ringbuffer.c:1619
 vprintk_store+0x558/0x870 kernel/printk/printk.c:2326
 vprintk_emit+0x15e/0x680 kernel/printk/printk.c:2408
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2447
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:86
 _printk+0x7a/0xa0 kernel/printk/printk.c:2457
 __netdev_printk+0x2d1/0x3e0 net/core/dev.c:11946
 netdev_info+0x99/0xc0 net/core/dev.c:11993
 __dev_set_allmulti+0x15b/0x240 net/core/dev.c:8809
 __dev_change_flags+0x329/0x410 net/core/dev.c:8971
 rtnl_configure_link net/core/rtnetlink.c:3542 [inline]
 rtnl_newlink_create+0x2ac/0x5d0 net/core/rtnetlink.c:3794
 __rtnl_newlink net/core/rtnetlink.c:3897 [inline]
 rtnl_newlink+0xe9f/0x1250 net/core/rtnetlink.c:4012
 rtnetlink_rcv_msg+0x651/0x710 net/core/rtnetlink.c:6922
 netlink_rcv_skb+0x12c/0x230 net/netlink/af_netlink.c:2542
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6949
 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline]
 netlink_unicast+0x599/0x670 net/netlink/af_netlink.c:1347
 netlink_sendmsg+0x5cc/0x6e0 net/netlink/af_netlink.c:1891
 sock_sendmsg_nosec net/socket.c:711 [inline]
 __sock_sendmsg+0x140/0x180 net/socket.c:726
 ____sys_sendmsg+0x312/0x410 net/socket.c:2583
 ___sys_sendmsg net/socket.c:2637 [inline]
 __sys_sendmsg+0x19d/0x230 net/socket.c:2669
 __do_sys_sendmsg net/socket.c:2674 [inline]
 __se_sys_sendmsg net/socket.c:2672 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2672
 x64_sys_call+0x2734/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000093928 -> 0x0000000000134ec0

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 31470 Comm: syz.3.8805 Not tainted 6.13.0-rc4-syzkaller-00012-g9b2ffa6148b1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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wireguard0: entered allmulticast mode