syzbot


KCSAN: data-race in pcpu_alloc_noprof / pcpu_balance_workfn

Status: moderation: reported on 2024/06/15 11:16
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+433f6493e3caec5344d0@syzkaller.appspotmail.com
First crash: 37d, last: 5d09h

Sample crash report:
==================================================================
BUG: KCSAN: data-race in pcpu_alloc_noprof / pcpu_balance_workfn

read-write to 0xffffffff886434dc of 4 bytes by task 9 on cpu 0:
 pcpu_update_empty_pages mm/percpu.c:602 [inline]
 pcpu_chunk_populated mm/percpu.c:1531 [inline]
 pcpu_balance_populated mm/percpu.c:2062 [inline]
 pcpu_balance_workfn+0x94e/0xa60 mm/percpu.c:2212
 process_one_work kernel/workqueue.c:3231 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3312
 worker_thread+0x526/0x700 kernel/workqueue.c:3390
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffffffff886434dc of 4 bytes by task 3086 on cpu 1:
 pcpu_alloc_noprof+0x9a7/0x10c0 mm/percpu.c:1894
 netdev_do_alloc_pcpu_stats net/core/dev.c:10283 [inline]
 register_netdevice+0x4c4/0xe30 net/core/dev.c:10379
 register_netdev+0x3b/0x50 net/core/dev.c:10572
 loopback_net_init+0x59/0x100 drivers/net/loopback.c:217
 ops_init+0x1ef/0x2b0 net/core/net_namespace.c:139
 setup_net+0x2ea/0x7c0 net/core/net_namespace.c:343
 copy_net_ns+0x37b/0x510 net/core/net_namespace.c:508
 create_new_namespaces+0x228/0x430 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xe6/0x120 kernel/nsproxy.c:228
 ksys_unshare+0x3da/0x720 kernel/fork.c:3308
 __do_sys_unshare kernel/fork.c:3379 [inline]
 __se_sys_unshare kernel/fork.c:3377 [inline]
 __x64_sys_unshare+0x1f/0x30 kernel/fork.c:3377
 x64_sys_call+0x2c8d/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:273
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000001 -> 0x00000004

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3086 Comm: syz-executor Not tainted 6.10.0-syzkaller-04472-g51835949dda3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
==================================================================
chnl_net:caif_netlink_parms(): no params data found
bridge0: port 1(bridge_slave_0) entered blocking state
bridge0: port 1(bridge_slave_0) entered disabled state
bridge_slave_0: entered allmulticast mode
bridge_slave_0: entered promiscuous mode
bridge0: port 2(bridge_slave_1) entered blocking state
bridge0: port 2(bridge_slave_1) entered disabled state
bridge_slave_1: entered allmulticast mode
bridge_slave_1: entered promiscuous mode
bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
team0: Port device team_slave_0 added
team0: Port device team_slave_1 added
batman_adv: batadv0: Adding interface: batadv_slave_0
batman_adv: batadv0: The MTU of interface batadv_slave_0 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1560 would solve the problem.
batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active
batman_adv: batadv0: Adding interface: batadv_slave_1
batman_adv: batadv0: The MTU of interface batadv_slave_1 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1560 would solve the problem.
batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
hsr_slave_0: entered promiscuous mode
hsr_slave_1: entered promiscuous mode
debugfs: Directory 'hsr0' with parent 'hsr' already present!
Cannot create hsr debugfs directory
netdevsim netdevsim0 netdevsim0: renamed from eth0
netdevsim netdevsim0 netdevsim1: renamed from eth1
netdevsim netdevsim0 netdevsim2: renamed from eth2
netdevsim netdevsim0 netdevsim3: renamed from eth3
8021q: adding VLAN 0 to HW filter on device bond0
8021q: adding VLAN 0 to HW filter on device team0
hsr0: Slave A (hsr_slave_0) is not up; please bring it up to get a fully working HSR network
hsr0: Slave B (hsr_slave_1) is not up; please bring it up to get a fully working HSR network
8021q: adding VLAN 0 to HW filter on device batadv0
veth0_vlan: entered promiscuous mode
veth1_vlan: entered promiscuous mode
veth0_macvtap: entered promiscuous mode
veth1_macvtap: entered promiscuous mode
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: batadv0: Interface activated: batadv_slave_1
netdevsim netdevsim0 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/07/17 20:26 upstream 51835949dda3 0f902625 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in pcpu_alloc_noprof / pcpu_balance_workfn
2024/06/22 07:59 upstream 35bb670d65fc edc5149a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in pcpu_alloc_noprof / pcpu_balance_workfn
2024/06/18 00:35 upstream 6226e74900d7 ce6011bc .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in pcpu_alloc_noprof / pcpu_balance_workfn
2024/06/17 13:49 upstream 6ba59ff42279 1f11cfd7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in pcpu_alloc_noprof / pcpu_balance_workfn
2024/06/17 04:02 upstream 6ba59ff42279 f429ab00 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in pcpu_alloc_noprof / pcpu_balance_workfn
2024/06/17 04:02 upstream 6ba59ff42279 f429ab00 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in pcpu_alloc_noprof / pcpu_balance_workfn
2024/06/16 08:29 upstream a3e18a540541 f429ab00 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in pcpu_alloc_noprof / pcpu_balance_workfn
2024/06/15 11:15 upstream 44ef20baed8e f429ab00 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in pcpu_alloc_noprof / pcpu_balance_workfn
* Struck through repros no longer work on HEAD.