================================================================== BUG: KCSAN: data-race in data_alloc / prb_reserve write to 0xffffffff86874d50 of 8 bytes by task 37 on cpu 1: data_alloc+0x280/0x2e0 kernel/printk/printk_ringbuffer.c:1102 prb_reserve+0x807/0xaf0 kernel/printk/printk_ringbuffer.c:1685 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2299 vprintk_emit+0x10d/0x580 kernel/printk/printk.c:2399 vprintk_default+0x26/0x30 kernel/printk/printk.c:2438 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2448 br_set_state+0x28c/0x390 net/bridge/br_stp.c:57 br_init_port net/bridge/br_stp_if.c:39 [inline] br_stp_enable_port+0x5e/0x110 net/bridge/br_stp_if.c:93 br_port_carrier_check+0x200/0x230 net/bridge/br_if.c:89 br_device_event+0x421/0x640 net/bridge/br.c:101 notifier_call_chain kernel/notifier.c:85 [inline] raw_notifier_call_chain+0x6f/0x1b0 kernel/notifier.c:453 call_netdevice_notifiers_info+0xae/0x100 net/core/dev.c:2229 netif_state_change+0x16d/0x1f0 net/core/dev.c:1583 linkwatch_do_dev+0xb9/0xf0 net/core/link_watch.c:186 __linkwatch_run_queue+0x582/0x850 net/core/link_watch.c:244 linkwatch_event+0x40/0x50 net/core/link_watch.c:304 process_one_work kernel/workqueue.c:3263 [inline] process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3346 worker_thread+0x582/0x770 kernel/workqueue.c:3427 kthread+0x489/0x510 kernel/kthread.c:463 ret_from_fork+0x122/0x1b0 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 read to 0xffffffff86874d50 of 8 bytes by task 9395 on cpu 0: desc_read kernel/printk/printk_ringbuffer.c:479 [inline] desc_push_tail kernel/printk/printk_ringbuffer.c:775 [inline] desc_reserve kernel/printk/printk_ringbuffer.c:921 [inline] prb_reserve+0x220/0xaf0 kernel/printk/printk_ringbuffer.c:1635 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2299 vprintk_emit+0x10d/0x580 kernel/printk/printk.c:2399 vprintk_default+0x26/0x30 kernel/printk/printk.c:2438 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2448 _fat_msg+0xa4/0xd0 fs/fat/misc.c:62 fat_clusters_flush+0x1d3/0x210 fs/fat/misc.c:79 fat_write_inode+0x73/0xd0 fs/fat/inode.c:921 write_inode fs/fs-writeback.c:1564 [inline] __writeback_single_inode+0x31c/0x7c0 fs/fs-writeback.c:1784 writeback_sb_inodes+0x48f/0xa30 fs/fs-writeback.c:2015 wb_writeback+0x252/0x5c0 fs/fs-writeback.c:2195 wb_do_writeback fs/fs-writeback.c:2342 [inline] wb_workfn+0x194/0x910 fs/fs-writeback.c:2382 process_one_work kernel/workqueue.c:3263 [inline] process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3346 worker_thread+0x582/0x770 kernel/workqueue.c:3427 kthread+0x489/0x510 kernel/kthread.c:463 ret_from_fork+0x122/0x1b0 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 value changed: 0xfffffffffffe75d0 -> 0x0000000000091068 Reported by Kernel Concurrency Sanitizer on: CPU: 0 UID: 0 PID: 9395 Comm: kworker/u8:9 Tainted: G W syzkaller #0 PREEMPT(voluntary) Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Workqueue: writeback wb_workfn (flush-7:1) ================================================================== FAT-fs (loop1): bread failed in fat_clusters_flush netdevsim netdevsim1 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim1 netdevsim3 (unregistering): unset [1, 1] type 2 family 0 port 20001 - 0 netdevsim netdevsim1 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim1 netdevsim2 (unregistering): unset [1, 1] type 2 family 0 port 20001 - 0 netdevsim netdevsim1 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim1 netdevsim1 (unregistering): unset [1, 1] type 2 family 0 port 20001 - 0 netdevsim netdevsim1 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim1 netdevsim0 (unregistering): unset [1, 1] type 2 family 0 port 20001 - 0 bond0 (unregistering): (slave bond_slave_0): Releasing backup interface bond0 (unregistering): (slave bond_slave_1): Releasing backup interface bond0 (unregistering): Released all slaves bond1 (unregistering): Released all slaves batman_adv: batadv0: Interface deactivated: batadv_slave_0 batman_adv: batadv0: Removing interface: batadv_slave_0 batman_adv: batadv0: Interface deactivated: batadv_slave_1 batman_adv: batadv0: Removing interface: batadv_slave_1 hsr0: left allmulticast mode veth1_macvtap: left promiscuous mode veth0_macvtap: left promiscuous mode team0 (unregistering): Port device team_slave_1 removed team0 (unregistering): Port device team_slave_0 removed netdevsim netdevsim9 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim9 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim9 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim9 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 bridge_slave_1: left allmulticast mode bridge_slave_1: left promiscuous mode bridge0: port 2(bridge_slave_1) entered disabled state bridge_slave_0: left allmulticast mode bridge_slave_0: left promiscuous mode bridge0: port 1(bridge_slave_0) entered disabled state bond0 (unregistering): (slave bond_slave_0): Releasing backup interface bond0 (unregistering): (slave bond_slave_1): Releasing backup interface bond0 (unregistering): Released all slaves bond0 (unregistering): Released all slaves tipc: Left network mode hsr_slave_0: left promiscuous mode hsr_slave_1: left promiscuous mode veth1_macvtap: left promiscuous mode veth0_macvtap: left promiscuous mode veth1_vlan: left promiscuous mode veth0_vlan: left promiscuous mode team0 (unregistering): Port device team_slave_1 removed bridge_slave_1: left allmulticast mode bridge_slave_1: left promiscuous mode bridge0: port 2(bridge_slave_1) entered disabled state bridge_slave_0: left allmulticast mode bridge_slave_0: left promiscuous mode bridge0: port 1(bridge_slave_0) entered disabled state bond0 (unregistering): (slave bond_slave_0): Releasing backup interface bond0 (unregistering): (slave bond_slave_1): Releasing backup interface bond0 (unregistering): Released all slaves hsr_slave_0: left promiscuous mode hsr_slave_1: left promiscuous mode batman_adv: batadv0: Removing interface: batadv_slave_0 batman_adv: batadv0: Removing interface: batadv_slave_1 team0 (unregistering): Port device team_slave_1 removed team0 (unregistering): Port device team_slave_0 removed