The patch titled
cgroups: use vmalloc for large cgroups pidlist allocations
has been added to the -mm tree. Its filename is
cgroups-use-vmalloc-for-large-cgroups-pidlist-allocations.patch
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------------------------------------------------------
Subject: cgroups: use vmalloc for large cgroups pidlist allocations
From: Ben Blum <bblum@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Paul Menage <menage@xxxxxxxxxx>
Acked-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
Cc: Matt Helsley <matthltc@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/cgroup.c | 47 +++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 42 insertions(+), 5 deletions(-)
diff -puN kernel/cgroup.c~cgroups-use-vmalloc-for-large-cgroups-pidlist-allocations kernel/cgroup.c
--- a/kernel/cgroup.c~cgroups-use-vmalloc-for-large-cgroups-pidlist-allocations
+++ a/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_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 cgr
* 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 cgr
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(str
/* 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);
_
Patches currently in -mm which might be from bblum@xxxxxxxxxx are
cgroups-add-a-read-only-procs-file-similar-to-tasks-that-shows-only-unique-tgids.patch
cgroups-ensure-correct-concurrent-opening-reading-of-pidlists-across-pid-namespaces.patch
cgroups-use-vmalloc-for-large-cgroups-pidlist-allocations.patch
cgroups-change-css_set-freeing-mechanism-to-be-under-rcu.patch
cgroups-let-ss-can_attach-and-ss-attach-do-whole-threadgroups-at-a-time.patch
cgroups-add-functionality-to-read-write-lock-clone_thread-forking-per-threadgroup.patch
cgroups-add-functionality-to-read-write-lock-clone_thread-forking-per-threadgroup-fix.patch
cgroups-add-ability-to-move-all-threads-in-a-process-to-a-new-cgroup-atomically.patch
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