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Message-ID: <CANaxB-x0wp2iC9Bp=xgH98MutQujvNMkUmZsobpxvWUc7H=SOw@mail.gmail.com>
Date: Wed, 12 Feb 2014 13:42:46 +0400
From: Andrey Wagin <avagin@...il.com>
To: netdev@...r.kernel.org
Subject: The kmemleak detector reports about leaked "struct net"
A kernel is compiled from Linus' tree without additional changes.
[root@...kins ~]# uname -a
Linux jenkins.criu.org 3.14.0-rc2 #162 SMP Tue Feb 11 01:09:33 MSK
2014 x86_64 x86_64 x86_64 GNU/Linux
Sometimes I have found reports from the kmemleak detector about leaked
"struct net".
Here is a script to reproduce these leaks:
[root@...kins ~]# cat test_net_ns.sh
ip net add test &&
ip link add name veth0 type veth peer name veth1 &&
ip link set dev veth1 netns test &&
ip net exec test ip link set up dev veth1 &&
ip link set up dev veth0 &&
brctl addif br0 veth0 &&
ip net exec test dhclient -4 veth1 -pf test.dhcp.pid -lf test.dhcp.lease &&
ip net exec test ip a
ip net exec test dhclient -r -pf test.dhcp.pid -lf test.dhcp.lease &&
ip net delete test &&
true || echo FAIL
This script creates a network namespace and a veth pair. One veth
device is attached to a bridge, another one is moved in namespace. The
dhclient gets ip address for the veth device in the test network
namespace. The final action is destroying the test network namespace.
[root@...kins ~]# echo clear > /sys/kernel/debug/kmemleak
[root@...kins ~]# bash -x test_net_ns.sh
+ ip net add test
+ ip link add name veth0 type veth peer name veth1
+ ip link set dev veth1 netns test
+ ip net exec test ip link set up dev veth1
+ ip link set up dev veth0
+ brctl addif br0 veth0
+ ip net exec test dhclient -4 veth1 -pf test.dhcp.pid -lf test.dhcp.lease
+ ip net exec test ip a
1: lo: <LOOPBACK> mtu 65536 qdisc noop state DOWN group default
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
23: veth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast
state UP group default qlen 1000
link/ether ae:f9:75:20:9c:92 brd ff:ff:ff:ff:ff:ff
inet 10.30.24.229/16 brd 10.30.255.255 scope global dynamic veth1
valid_lft 3558sec preferred_lft 3558sec
inet6 fe80::acf9:75ff:fe20:9c92/64 scope link
valid_lft forever preferred_lft forever
+ ip net exec test ip r
default via 10.30.0.1 dev veth1
10.30.0.0/16 dev veth1 proto kernel scope link src 10.30.24.229
+ ip net exec test dhclient -r -pf test.dhcp.pid -lf test.dhcp.lease
+ ip net delete test
+ true
[root@...kins ~]# echo scan > /sys/kernel/debug/kmemleak
[root@...kins ~]# cat /sys/kernel/debug/kmemleak
[root@...kins ~]# echo scan > /sys/kernel/debug/kmemleak
[root@...kins ~]# cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff88009bfc3c80 (size 128):
comm "ip", pid 25985, jiffies 4346037464 (age 4507.484s)
hex dump (first 32 bytes):
0d 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 b0 53 eb 0e 01 88 ff ff .........S......
backtrace:
[<ffffffff8176858e>] kmemleak_alloc+0x5e/0xc0
[<ffffffff811f6d3f>] __kmalloc+0x1bf/0x2e0
[<ffffffff81636351>] net_alloc_generic+0x21/0x30
[<ffffffff81636855>] copy_net_ns+0x45/0x160
[<ffffffff810b4c91>] create_new_namespaces+0x101/0x1b0
[<ffffffff810b4dc5>] unshare_nsproxy_namespaces+0x85/0xe0
[<ffffffff810810eb>] SyS_unshare+0x1ab/0x350
[<ffffffff8177bfe9>] system_call_fastpath+0x16/0x1b
[<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffff88006b3a92c0 (size 4416):
comm "ip", pid 25985, jiffies 4346037464 (age 4507.484s)
hex dump (first 32 bytes):
02 00 00 00 00 00 00 00 08 08 00 00 ad 4e ad de .............N..
ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff ................
backtrace:
[<ffffffff8176858e>] kmemleak_alloc+0x5e/0xc0
[<ffffffff811f5f47>] kmem_cache_alloc+0x217/0x2a0
[<ffffffff81636875>] copy_net_ns+0x65/0x160
[<ffffffff810b4c91>] create_new_namespaces+0x101/0x1b0
[<ffffffff810b4dc5>] unshare_nsproxy_namespaces+0x85/0xe0
[<ffffffff810810eb>] SyS_unshare+0x1ab/0x350
[<ffffffff8177bfe9>] system_call_fastpath+0x16/0x1b
[<ffffffffffffffff>] 0xffffffffffffffff
[root@...kins ~]# lsmod
Module Size Used by
veth 13604 0
binfmt_misc 17392 0
ip6table_filter 12815 0
ip6_tables 26677 1 ip6table_filter
tun 32328 0
netlink_diag 12658 0
af_packet_diag 12604 0
udp_diag 12794 0
tcp_diag 12591 0
inet_diag 18278 2 tcp_diag,udp_diag
unix_diag 12594 0
bridge 116990 0
stp 12989 1 bridge
llc 14094 2 stp,bridge
btrfs 933081 1
xor 21366 1 btrfs
raid6_pq 96781 1 btrfs
joydev 17642 0
microcode 19962 0
i2c_piix4 22148 0
virtio_net 28194 0
i2c_core 38545 1 i2c_piix4
virtio_balloon 13451 0
pcspkr 12718 0
virtio_blk 18030 6
virtio_pci 17713 0
virtio_ring 19923 4 virtio_blk,virtio_net,virtio_pci,virtio_balloon
virtio 14207 4 virtio_blk,virtio_net,virtio_pci,virtio_balloon
floppy 73436 0
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