sukadev@xxxxxxxxxx wrote:
sukadev@xxxxxxxxxx [sukadev@xxxxxxxxxx] wrote:
| Pavel,
|
| We seem to have a memory leak. Its new in this patchset (i.e the
| following test ran fine on the 2.6.22-rc6-mm1 patchset).
|
| To repro: run "pidns_exec ./mypid" in a tight-loop - where mypid.c
| is:
|
| #include <stdio.h>
| #include <unistd.h>
|
| main()
| {
| printf("Pid %d, Ppid %d, Pgid %d, Sid %d\n",
| getpid(), getppid(), getpgid(0), getsid(0));
| }
|
| I ran into OOM in about 30 mins. I am still investigating.
|
| BTW, can we include a simple test program like the pidns_exec in this
| patch-0 for whoever want to play with pidns ?
|
| Suka
|
I think the problem is in create_pid_namespace(). kref_init() sets the
refcount to 1 and then we do a get_pid_ns() which sets it to 2.
free_nsproxy() frees one of this references, but the other is never
freed.
That's it! I've switched from my old fast (and bad) reference counting
scheme to new slow (and correct) one, but forgot to remove this "get".
This is the real problem. Thanks :)
This patch seems to fix the leak. The patch also creates a slab cache
for the pid_namespace
OK, I'll include this patch. Thanks.
---
Create a slab-cache for 'struct pid_namespace' and fix a memory leak
due to an extra reference in create_pid_namespace().
---
kernel/pid.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
Index: lx26-23-rc1-mm1/kernel/pid.c
===================================================================
--- lx26-23-rc1-mm1.orig/kernel/pid.c 2007-07-26 20:08:16.000000000 -0700
+++ lx26-23-rc1-mm1/kernel/pid.c 2007-07-26 22:31:42.000000000 -0700
@@ -35,6 +35,7 @@
static struct hlist_head *pid_hash;
static int pidhash_shift;
struct pid init_struct_pid = INIT_STRUCT_PID;
+static struct kmem_cache *pid_ns_cachep;
int pid_max = PID_MAX_DEFAULT;
@@ -525,7 +526,7 @@ static struct pid_namespace *create_pid_
struct pid_namespace *ns;
int i;
- ns = kmalloc(sizeof(struct pid_namespace), GFP_KERNEL);
+ ns = kmem_cache_alloc(pid_ns_cachep, GFP_KERNEL);
if (ns == NULL)
goto out;
@@ -544,7 +545,6 @@ static struct pid_namespace *create_pid_
set_bit(0, ns->pidmap[0].page);
atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
- get_pid_ns(ns);
for (i = 1; i < PIDMAP_ENTRIES; i++) {
ns->pidmap[i].page = 0;
@@ -556,7 +556,7 @@ static struct pid_namespace *create_pid_
out_free_map:
kfree(ns->pidmap[0].page);
out_free:
- kfree(ns);
+ kmem_cache_free(pid_ns_cachep, ns);
out:
return ERR_PTR(-ENOMEM);
}
@@ -567,7 +567,7 @@ static void destroy_pid_namespace(struct
for (i = 0; i < PIDMAP_ENTRIES; i++)
kfree(ns->pidmap[i].page);
- kfree(ns);
+ kmem_cache_free(pid_ns_cachep, ns);
}
struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *old_ns)
@@ -687,4 +687,6 @@ void __init pidmap_init(void)
init_pid_ns.pid_cachep = create_pid_cachep(1);
if (init_pid_ns.pid_cachep == NULL)
panic("Can't create pid_1 cachep\n");
+
+ pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
}
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