==================================================================
BUG: KCSAN: data-race in data_alloc / prb_reserve

write to 0xffffffff86c69438 of 8 bytes by task 13339 on cpu 0:
 data_alloc+0x308/0x380 kernel/printk/printk_ringbuffer.c:1130
 prb_reserve+0x8e3/0xaf0 kernel/printk/printk_ringbuffer.c:1727
 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
 __ext4_error+0x225/0x2e0 fs/ext4/super.c:829
 __ext4_get_inode_loc+0x38b/0x930 fs/ext4/inode.c:4885
 __ext4_get_inode_loc_noinmem fs/ext4/inode.c:5004 [inline]
 ext4_write_inode+0x1ce/0x3c0 fs/ext4/inode.c:5843
 write_inode fs/fs-writeback.c:1607 [inline]
 __writeback_single_inode+0x327/0x660 fs/fs-writeback.c:1850
 writeback_single_inode+0x16d/0x400 fs/fs-writeback.c:1906
 write_inode_now+0xef/0x120 fs/fs-writeback.c:3060
 iput_final fs/inode.c:2009 [inline]
 iput+0x321/0x5a0 fs/inode.c:2068
 ext4_process_orphan+0x1a4/0x1c0 fs/ext4/orphan.c:358
 ext4_orphan_cleanup+0x6a6/0xa10 fs/ext4/orphan.c:472
 __ext4_fill_super fs/ext4/super.c:5705 [inline]
 ext4_fill_super+0x33ab/0x3760 fs/ext4/super.c:5828
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1634
 get_tree_bdev+0x1f/0x30 fs/super.c:1657
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5860
 vfs_get_tree+0x57/0x1d0 fs/super.c:1694
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3765 [inline]
 do_new_mount+0x288/0x8d0 fs/namespace.c:3841
 path_mount+0x4ad/0xb90 fs/namespace.c:4161
 do_mount fs/namespace.c:4174 [inline]
 __do_sys_mount fs/namespace.c:4390 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4367
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4367
 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+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff86c69438 of 8 bytes by task 4910 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:496 [inline]
 desc_push_tail kernel/printk/printk_ringbuffer.c:792 [inline]
 desc_reserve kernel/printk/printk_ringbuffer.c:938 [inline]
 prb_reserve+0x21a/0xaf0 kernel/printk/printk_ringbuffer.c:1677
 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:12966
 netdev_info+0xa6/0xd0 net/core/dev.c:13013
 __dev_set_promiscuity+0x1e5/0x3c0 net/core/dev.c:9614
 __dev_set_rx_mode+0x1e4/0x220 net/core/dev_addr_lists.c:1384
 dev_uc_del+0x144/0x160 net/core/dev_addr_lists.c:845
 macvlan_stop+0x1b3/0x260 drivers/net/macvlan.c:723
 __dev_close_many+0x24d/0x460 net/core/dev.c:1776
 netif_close_many+0x101/0x2d0 net/core/dev.c:1802
 unregister_netdevice_many_notify+0x500/0x1550 net/core/dev.c:12410
 unregister_netdevice_many net/core/dev.c:12501 [inline]
 default_device_exit_batch+0x5d7/0x630 net/core/dev.c:13093
 ops_exit_list net/core/net_namespace.c:205 [inline]
 ops_undo_list+0x2ca/0x420 net/core/net_namespace.c:252
 cleanup_net+0x37c/0x5b0 net/core/net_namespace.c:702
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0x4d4/0x9a0 kernel/workqueue.c:3405
 worker_thread+0x569/0x750 kernel/workqueue.c:3486
 kthread+0x221/0x270 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0xfffffffffffce610 -> 0x000000000007bf88

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 4910 Comm: kworker/u8:21 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
Workqueue: netns cleanup_net
==================================================================
veth0_macvtap: left promiscuous mode
veth1_vlan: left promiscuous mode
veth0_vlan: left promiscuous mode
team0 (unregistering): Port device team_slave_1 removed
team0 (unregistering): Port device team_slave_0 removed
GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog