On 2017-11-08 16:04, Vasily Averin wrote:
> On 2017-11-08 15:09, Alexander Shishkin wrote:
>> On Mon, Nov 06, 2017 at 09:22:18AM +0300, Vasily Averin wrote:
>>> Fixes: commit e422267322cd ("perf: Add PERF_RECORD_NAMESPACES to include
>>> namespaces related info")
>>> Signed-off-by: Vasily Averin <v...@virtuozzo.com>
>>
>> The change description is missing. One needs to open the source code and
>> look for proof of correctness for this patch.
>
> perf_fill_ns_link_info() calls ns_get_path()
> it returns ns_path with increased mnt and dentry counters.
>
> Problem is that nodody decrement these counters.
>
> You can call ./perf record --namespaces unshare -m
> and look how grows mount counter on nsfs_mnt.
Situation is even worse, leaked dentry does not allow to free related
namespaces.
[root@localhost ~]# uname -a
Linux localhost.localdomain 4.14.0+ #10 SMP Wed Nov 15 00:31:34 MSK 2017 x86_64
x86_64 x86_64 GNU/Linux
VvS: without --namespace perf works correctly
[root@localhost ~]# grep namespace /proc/slabinfo
pid_namespace 0 0 2568 12 8 : tunables 0 0 0 :
slabdata 0 0 0
user_namespace 0 0 824 39 8 : tunables 0 0 0 :
slabdata 0 0 0
net_namespace 0 5 6272 5 8 : tunables 0 0 0 :
slabdata 1 1 0
[root@localhost ~]# perf record -q unshare -n -U -p --fork true
[root@localhost ~]# grep namespace /proc/slabinfo
pid_namespace 0 12 2568 12 8 : tunables 0 0 0 :
slabdata 1 1 0
user_namespace 0 39 824 39 8 : tunables 0 0 0 :
slabdata 1 1 0
net_namespace 0 5 6272 5 8 : tunables 0 0 0 :
slabdata 1 1 0
VvS: with --namespace perf leaks namespaces
[root@localhost ~]# perf record -q --namespace unshare -n -U -p --fork true
[root@localhost ~]# grep namespace /proc/slabinfo
pid_namespace 1 12 2568 12 8 : tunables 0 0 0 :
slabdata 1 1 0
user_namespace 1 39 824 39 8 : tunables 0 0 0 :
slabdata 1 1 0
net_namespace 1 5 6272 5 8 : tunables 0 0 0 :
slabdata 1 1 0
VvS: ... and once again, to be sure
[root@localhost ~]# perf record -q --namespace unshare -n -U -p --fork true
[root@localhost ~]# grep namespace /proc/slabinfo
pid_namespace 2 12 2568 12 8 : tunables 0 0 0 :
slabdata 1 1 0
user_namespace 2 39 824 39 8 : tunables 0 0 0 :
slabdata 1 1 0
net_namespace 2 5 6272 5 8 : tunables 0 0 0 :
slabdata 1 1 0
kmemleak also detects leaks dentry, inode, related structures and namespaces
unreferenced object 0xffff998008e76738 (size 192): <<< dentry
comm "unshare", pid 1436, jiffies 4294786539 (age 509.114s)
[<ffffffffbb29f495>] __ns_get_path+0xf5/0x160
[<ffffffffbb29f5a8>] ns_get_path+0x28/0x50
[<ffffffffbb1adb00>] perf_fill_ns_link_info+0x20/0x80
[<ffffffffbb1b1ba7>] perf_event_namespaces.part.101+0xd7/0x120
[<ffffffffbb09e85d>] copy_process.part.34+0x171d/0x1ae0
[<ffffffffbb09eddc>] _do_fork+0xcc/0x390
[<ffffffffbb003a11>] do_syscall_64+0x61/0x170
[<ffffffffbb86e6fb>] return_from_SYSCALL_64+0x0/0x65
[<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffff998008e7c928 (size 600): <<< inode
comm "unshare", pid 1436, jiffies 4294786539 (age 509.114s)
[<ffffffffbb286f4e>] new_inode_pseudo+0xe/0x60
[<ffffffffbb29f3e2>] __ns_get_path+0x42/0x160
[<ffffffffbb29f5a8>] ns_get_path+0x28/0x50
...
unreferenced object 0xffff99800cacd320 (size 40): <<< inode_security_struct
comm "unshare", pid 1436, jiffies 4294786539 (age 509.114s)
[<ffffffffbb383876>] security_inode_alloc+0x36/0x50
[<ffffffffbb284bd5>] inode_init_always+0xf5/0x1d0
[<ffffffffbb28505b>] alloc_inode+0x2b/0x80
[<ffffffffbb286f4e>] new_inode_pseudo+0xe/0x60
[<ffffffffbb29f3e2>] __ns_get_path+0x42/0x160
...
unreferenced object 0xffff99800cb88a10 (size 2232): <<< pid_namespace
comm "unshare", pid 1436, jiffies 4294786439 (age 509.214s)
[<ffffffffbb0c0104>] create_new_namespaces+0xd4/0x1b0
[<ffffffffbb0c0359>] unshare_nsproxy_namespaces+0x59/0xb0
[<ffffffffbb09f415>] SyS_unshare+0x1e5/0x370
[<ffffffffbb86e673>] entry_SYSCALL_64_fastpath+0x1a/0x7d
[<ffffffffffffffff>] 0xffffffffffffffff
I've resend the patch as "[PATCH] memory leaks triggered by perf --namespace"
Thank you,
Vasily Averin
