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cgroups: use vmalloc for large cgroups pidlist allocations

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Separates all pidlist allocation requests to a separate function that
judges based on the requested size whether or not the array needs to be
vmalloced or can be gotten via kmalloc, and similar for kfree/vfree.

Signed-off-by: Ben Blum <bblum@google.com>
Signed-off-by: Paul Menage <menage@google.com>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ben Blum 2009-09-23 15:56:28 -07:00 committed by Linus Torvalds
parent 72a8cb30d1
commit d1d9fd3308
1 changed files with 42 additions and 5 deletions
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47
kernel/cgroup.c
View file

@ -50,6 +50,7 @@
#include <linux/smp_lock.h>
#include <linux/pid_namespace.h>
#include <linux/idr.h>
#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
#include <asm/atomic.h>
@ -2350,6 +2351,42 @@ int cgroup_scan_tasks(struct cgroup_scanner *scan)
*
*/
/*
* The following two functions "fix" the issue where there are more pids
* than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
* TODO: replace with a kernel-wide solution to this problem
*/
#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
static void *pidlist_allocate(int count)
{
if (PIDLIST_TOO_LARGE(count))
return vmalloc(count * sizeof(pid_t));
else
return kmalloc(count * sizeof(pid_t), GFP_KERNEL);
}
static void pidlist_free(void *p)
{
if (is_vmalloc_addr(p))
vfree(p);
else
kfree(p);
}
static void *pidlist_resize(void *p, int newcount)
{
void *newlist;
/* note: if new alloc fails, old p will still be valid either way */
if (is_vmalloc_addr(p)) {
newlist = vmalloc(newcount * sizeof(pid_t));
if (!newlist)
return NULL;
memcpy(newlist, p, newcount * sizeof(pid_t));
vfree(p);
} else {
newlist = krealloc(p, newcount * sizeof(pid_t), GFP_KERNEL);
}
return newlist;
}
/*
* pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
* If the new stripped list is sufficiently smaller and there's enough memory
@ -2389,7 +2426,7 @@ after:
* we'll just stay with what we've got.
*/
if (PIDLIST_REALLOC_DIFFERENCE(length, dest)) {
newlist = krealloc(list, dest * sizeof(pid_t), GFP_KERNEL);
newlist = pidlist_resize(list, dest);
if (newlist)
*p = newlist;
}
@ -2470,7 +2507,7 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
* show up until sometime later on.
*/
length = cgroup_task_count(cgrp);
array = kmalloc(length * sizeof(pid_t), GFP_KERNEL);
array = pidlist_allocate(length);
if (!array)
return -ENOMEM;
/* now, populate the array */
@ -2494,11 +2531,11 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
length = pidlist_uniq(&array, length);
l = cgroup_pidlist_find(cgrp, type);
if (!l) {
kfree(array);
pidlist_free(array);
return -ENOMEM;
}
/* store array, freeing old if necessary - lock already held */
kfree(l->list);
pidlist_free(l->list);
l->list = array;
l->length = length;
l->use_count++;
@ -2659,7 +2696,7 @@ static void cgroup_release_pid_array(struct cgroup_pidlist *l)
/* we're the last user if refcount is 0; remove and free */
list_del(&l->links);
mutex_unlock(&l->owner->pidlist_mutex);
kfree(l->list);
pidlist_free(l->list);
put_pid_ns(l->key.ns);
up_write(&l->mutex);
kfree(l);