[EXT4 FS bs=4096, gc=1, bpg=32768, ipg=32, mo=e842c11c, mo2=0002]
System zones: 
==================================================================
BUG: KCSAN: data-race in data_alloc / data_push_tail

write to 0xffffffff8937c738 of 8 bytes by task 25828 on cpu 1:
 data_alloc+0x259/0x390 kernel/printk/printk_ringbuffer.c:1116
 prb_reserve+0x8d7/0xae0 kernel/printk/printk_ringbuffer.c:1724
 vprintk_store+0x54a/0x910 kernel/printk/printk.c:2354
 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2455
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2504
 __netdev_printk+0x310/0x370 net/core/dev.c:12924
 netdev_info+0xa6/0xd0 net/core/dev.c:12971
 __dev_set_promiscuity+0x1fb/0x3f0 net/core/dev.c:9558
 netif_set_promiscuity+0x39/0x90 net/core/dev.c:9593
 dev_set_promiscuity+0xc1/0x170 net/core/dev_api.c:287
 br_port_set_promisc net/bridge/br_if.c:108 [inline]
 br_manage_promisc+0xf1/0x370 net/bridge/br_if.c:157
 nbp_update_port_count+0xc3/0xe0 net/bridge/br_if.c:242
 br_add_if+0x502/0xa60 net/bridge/br_if.c:627
 br_add_slave+0x2c/0x40 net/bridge/br_device.c:375
 do_set_master+0x390/0x460 net/core/rtnetlink.c:2963
 do_setlink+0x97b/0x2940 net/core/rtnetlink.c:3165
 rtnl_changelink net/core/rtnetlink.c:3776 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3935 [inline]
 rtnl_newlink+0xfd9/0x1330 net/core/rtnetlink.c:4072
 rtnetlink_rcv_msg+0x64b/0x720 net/core/rtnetlink.c:6958
 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2550
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6985
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x5c0/0x690 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x5c8/0x6f0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 __sys_sendto+0x470/0x4d0 net/socket.c:2206
 __do_sys_sendto net/socket.c:2213 [inline]
 __se_sys_sendto net/socket.c:2209 [inline]
 __x64_sys_sendto+0x76/0x90 net/socket.c:2209
 x64_sys_call+0x2d35/0x3020 arch/x86/include/generated/asm/syscalls_64.h:45
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff8937c738 of 8 bytes by task 25873 on cpu 0:
 data_make_reusable kernel/printk/printk_ringbuffer.c:608 [inline]
 data_push_tail+0x100/0x470 kernel/printk/printk_ringbuffer.c:693
 data_alloc+0x11b/0x390 kernel/printk/printk_ringbuffer.c:1089
 prb_reserve+0x8d7/0xae0 kernel/printk/printk_ringbuffer.c:1724
 vprintk_store+0x54a/0x910 kernel/printk/printk.c:2354
 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2455
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2504
 debug_print_tree+0x17/0x120 fs/ext4/block_validity.c:132
 ext4_setup_system_zone+0x453/0x640 fs/ext4/block_validity.c:265
 __ext4_fill_super fs/ext4/super.c:5596 [inline]
 ext4_fill_super+0x3095/0x37c0 fs/ext4/super.c:5793
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1694
 get_tree_bdev+0x1f/0x30 fs/super.c:1717
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5825
 vfs_get_tree+0x57/0x1d0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3760 [inline]
 do_new_mount+0x288/0x8d0 fs/namespace.c:3836
 path_mount+0x4d0/0xbc0 fs/namespace.c:4146
 do_mount fs/namespace.c:4159 [inline]
 __do_sys_mount fs/namespace.c:4348 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4325
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4325
 x64_sys_call+0x2d61/0x3020 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000100000521 -> 0x0000000100001107

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 25873 Comm: syz.3.6687 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================
0-2
, 18-18
, 34-34

EXT4-fs (loop3): too many log groups per flexible block group
EXT4-fs (loop3): failed to initialize mballoc (-12)
EXT4-fs (loop3): mount failed