[moderation] [net?] KCSAN: data-race in pcpu_alloc / pcpu_balance_workfn (6)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8c1f0c38b310 Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12bebbcf280000
kernel config: https://syzkaller.appspot.com/x/.config?x=78c1b724e055b4d3
dashboard link: https://syzkaller.appspot.com/bug?extid=443f491a1ce0d21e2d75
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
CC: [da...@davemloft.net dsa...@kernel.org edum...@google.com ku...@kernel.org linux-...@vger.kernel.org net...@vger.kernel.org pab...@redhat.com]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8bd893814229/disk-8c1f0c38.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/21b5470da094/vmlinux-8c1f0c38.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1a67c15b3ab0/bzImage-8c1f0c38.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+443f49...@syzkaller.appspotmail.com

veth0_macvtap: entered promiscuous mode
veth1_macvtap: entered promiscuous mode
==================================================================
BUG: KCSAN: data-race in pcpu_alloc / pcpu_balance_workfn

read-write to 0xffffffff86f5a5d4 of 4 bytes by task 3160 on cpu 1:
pcpu_update_empty_pages mm/percpu.c:602 [inline]
pcpu_chunk_populated mm/percpu.c:1531 [inline]
pcpu_balance_populated mm/percpu.c:2088 [inline]
pcpu_balance_workfn+0x96f/0xa80 mm/percpu.c:2238
process_one_work+0x3e6/0x750 kernel/workqueue.c:2405
worker_thread+0x5f2/0xa10 kernel/workqueue.c:2552
kthread+0x1d7/0x210 kernel/kthread.c:379
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

read to 0xffffffff86f5a5d4 of 4 bytes by task 3080 on cpu 0:
pcpu_alloc+0xa59/0x1280 mm/percpu.c:1870
__alloc_percpu_gfp+0x26/0x30 mm/percpu.c:1930
fib_nh_common_init+0x48/0x2b0 net/ipv4/fib_semantics.c:590
fib_nh_init+0x64/0x1a0 net/ipv4/fib_semantics.c:629
fib_create_info+0xa22/0x1500 net/ipv4/fib_semantics.c:1492
fib_table_insert+0x101/0xf70 net/ipv4/fib_trie.c:1236
fib_magic+0x1a1/0x1f0 net/ipv4/fib_frontend.c:1104
fib_add_ifaddr+0x2dc/0x320 net/ipv4/fib_frontend.c:1148
fib_netdev_event+0x357/0x430 net/ipv4/fib_frontend.c:1486
notifier_call_chain kernel/notifier.c:93 [inline]
raw_notifier_call_chain+0x6b/0x1c0 kernel/notifier.c:461
__dev_notify_flags+0x205/0x3d0
dev_change_flags+0xab/0xd0 net/core/dev.c:8645
do_setlink+0x9ad/0x23a0 net/core/rtnetlink.c:2867
__rtnl_newlink net/core/rtnetlink.c:3648 [inline]
rtnl_newlink+0x10cb/0x15a0 net/core/rtnetlink.c:3695
rtnetlink_rcv_msg+0x807/0x8c0 net/core/rtnetlink.c:6417
netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2546
rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6435
netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
netlink_unicast+0x56f/0x640 net/netlink/af_netlink.c:1365
netlink_sendmsg+0x665/0x770 net/netlink/af_netlink.c:1913
sock_sendmsg_nosec net/socket.c:724 [inline]
sock_sendmsg net/socket.c:747 [inline]
__sys_sendto+0x246/0x300 net/socket.c:2144
__do_sys_sendto net/socket.c:2156 [inline]
__se_sys_sendto net/socket.c:2152 [inline]
__x64_sys_sendto+0x78/0x90 net/socket.c:2152
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000001 -> 0x00000004

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3080 Comm: syz-executor.3 Not tainted 6.4.0-rc6-syzkaller-00279-g8c1f0c38b310 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
==================================================================
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
EXT4-fs (loop3): unmounting filesystem 00000000-0000-0000-0000-000000000000.
EXT4-fs (loop3): unmounting filesystem 00000000-0000-0000-0000-000000000000.
EXT4-fs (loop3): unmounting filesystem 00000000-0000-0000-0000-000000000000.
EXT4-fs (loop3): unmounting filesystem 00000000-0000-0000-0000-000000000000.


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.