==================================================================
BUG: KCSAN: data-race in pcpu_alloc / pcpu_block_update_hint_alloc

read-write to 0xffffffff883db4dc of 4 bytes by task 3093 on cpu 1:
 pcpu_update_empty_pages mm/percpu.c:602 [inline]
 pcpu_block_update_hint_alloc+0x5db/0x6a0 mm/percpu.c:923
 pcpu_alloc_area+0x49f/0x4d0 mm/percpu.c:1258
 pcpu_alloc+0x4b3/0x10d0 mm/percpu.c:1808
 __alloc_percpu_gfp+0x26/0x30 mm/percpu.c:1930
 mem_cgroup_alloc mm/memcontrol.c:5511 [inline]
 mem_cgroup_css_alloc+0x130/0xb40 mm/memcontrol.c:5569
 css_create kernel/cgroup/cgroup.c:5548 [inline]
 cgroup_apply_control_enable+0x1e5/0xa00 kernel/cgroup/cgroup.c:3217
 cgroup_mkdir+0xb93/0xc70 kernel/cgroup/cgroup.c:5762
 kernfs_iop_mkdir+0x12f/0x1f0 fs/kernfs/dir.c:1246
 vfs_mkdir+0x1f7/0x300 fs/namei.c:4126
 do_mkdirat+0x12f/0x2a0 fs/namei.c:4149
 __do_sys_mkdirat fs/namei.c:4164 [inline]
 __se_sys_mkdirat fs/namei.c:4162 [inline]
 __x64_sys_mkdirat+0x50/0x60 fs/namei.c:4162
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

read to 0xffffffff883db4dc of 4 bytes by task 3105 on cpu 0:
 pcpu_alloc+0x9aa/0x10d0 mm/percpu.c:1868
 __alloc_percpu_gfp+0x26/0x30 mm/percpu.c:1930
 fib_nh_common_init+0x48/0x2b0 net/ipv4/fib_semantics.c:591
 fib_nh_init+0x64/0x1b0 net/ipv4/fib_semantics.c:630
 fib_create_info+0xa26/0x1500 net/ipv4/fib_semantics.c:1497
 fib_table_insert+0x101/0xfa0 net/ipv4/fib_trie.c:1237
 fib_magic+0x1a1/0x1f0 net/ipv4/fib_frontend.c:1104
 fib_add_ifaddr+0xd5/0x330 net/ipv4/fib_frontend.c:1126
 fib_inetaddr_event+0xb9/0x200 net/ipv4/fib_frontend.c:1440
 notifier_call_chain kernel/notifier.c:93 [inline]
 blocking_notifier_call_chain+0x94/0x200 kernel/notifier.c:388
 __inet_insert_ifa+0x4cc/0x5e0 net/ipv4/devinet.c:556
 inet_rtm_newaddr+0x8df/0xc30 net/ipv4/devinet.c:981
 rtnetlink_rcv_msg+0x82e/0x8e0 net/core/rtnetlink.c:6595
 netlink_rcv_skb+0x12c/0x230 net/netlink/af_netlink.c:2559
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6613
 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline]
 netlink_unicast+0x58d/0x660 net/netlink/af_netlink.c:1361
 netlink_sendmsg+0x5d3/0x6e0 net/netlink/af_netlink.c:1905
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x140/0x180 net/socket.c:745
 __sys_sendto+0x1e5/0x260 net/socket.c:2191
 __do_sys_sendto net/socket.c:2203 [inline]
 __se_sys_sendto net/socket.c:2199 [inline]
 __x64_sys_sendto+0x78/0x90 net/socket.c:2199
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

value changed: 0x00000002 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3105 Comm: syz-executor.3 Not tainted 6.9.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
==================================================================
veth0_vlan: entered promiscuous mode
veth1_vlan: entered promiscuous mode
veth0_macvtap: entered promiscuous mode
veth1_macvtap: entered promiscuous mode
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_0
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_0
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_0
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: batadv0: Interface activated: batadv_slave_0
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3f) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3f) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3f) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: batadv0: Interface activated: batadv_slave_1
netdevsim netdevsim3 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim3 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim3 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim3 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0