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authorBen Blum <bblum@google.com>2009-09-23 15:56:28 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-24 07:20:58 -0700
commitd1d9fd3308fdef6b4bf564fa3d6cfe35b68b50bc (patch)
tree8de392166f2edb696950a90e468ef27f043be509 /kernel
parent72a8cb30d10d4041c455a7054607a7d519167c87 (diff)
cgroups: use vmalloc for large cgroups pidlist allocations
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup.c47
1 files changed, 42 insertions, 5 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 97194ba1201..3e356b05b2d 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -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>
@@ -2351,6 +2352,42 @@ 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
* to allocate a new buffer, will let go of the unneeded memory. Returns the
@@ -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);