memcg: add memcg sanity checks at allocating and freeing pages
Add checks at allocating or freeing a page whether the page is used (iow,
charged) from the view point of memcg.
This check may be useful in debugging a problem and we did similar checks
before the commit 52d4b9ac(memcg: allocate all page_cgroup at boot).
This patch adds some overheads at allocating or freeing memory, so it's
enabled only when CONFIG_DEBUG_VM is enabled.
Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 5bb7be2..5a5ce70 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -151,6 +151,10 @@
void mem_cgroup_split_huge_fixup(struct page *head, struct page *tail);
#endif
+#ifdef CONFIG_DEBUG_VM
+bool mem_cgroup_bad_page_check(struct page *page);
+void mem_cgroup_print_bad_page(struct page *page);
+#endif
#else /* CONFIG_CGROUP_MEM_RES_CTLR */
struct mem_cgroup;
@@ -352,5 +356,18 @@
#endif /* CONFIG_CGROUP_MEM_CONT */
+#if !defined(CONFIG_CGROUP_MEM_RES_CTLR) || !defined(CONFIG_DEBUG_VM)
+static inline bool
+mem_cgroup_bad_page_check(struct page *page)
+{
+ return false;
+}
+
+static inline void
+mem_cgroup_print_bad_page(struct page *page)
+{
+}
+#endif
+
#endif /* _LINUX_MEMCONTROL_H */
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 3a2d54b..0356cb6 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3046,6 +3046,52 @@
return ret;
}
+#ifdef CONFIG_DEBUG_VM
+static struct page_cgroup *lookup_page_cgroup_used(struct page *page)
+{
+ struct page_cgroup *pc;
+
+ pc = lookup_page_cgroup(page);
+ if (likely(pc) && PageCgroupUsed(pc))
+ return pc;
+ return NULL;
+}
+
+bool mem_cgroup_bad_page_check(struct page *page)
+{
+ if (mem_cgroup_disabled())
+ return false;
+
+ return lookup_page_cgroup_used(page) != NULL;
+}
+
+void mem_cgroup_print_bad_page(struct page *page)
+{
+ struct page_cgroup *pc;
+
+ pc = lookup_page_cgroup_used(page);
+ if (pc) {
+ int ret = -1;
+ char *path;
+
+ printk(KERN_ALERT "pc:%p pc->flags:%lx pc->mem_cgroup:%p",
+ pc, pc->flags, pc->mem_cgroup);
+
+ path = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (path) {
+ rcu_read_lock();
+ ret = cgroup_path(pc->mem_cgroup->css.cgroup,
+ path, PATH_MAX);
+ rcu_read_unlock();
+ }
+
+ printk(KERN_CONT "(%s)\n",
+ (ret < 0) ? "cannot get the path" : path);
+ kfree(path);
+ }
+}
+#endif
+
static DEFINE_MUTEX(set_limit_mutex);
static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3a58221..8e5726a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -53,6 +53,7 @@
#include <linux/compaction.h>
#include <trace/events/kmem.h>
#include <linux/ftrace_event.h>
+#include <linux/memcontrol.h>
#include <asm/tlbflush.h>
#include <asm/div64.h>
@@ -565,7 +566,8 @@
if (unlikely(page_mapcount(page) |
(page->mapping != NULL) |
(atomic_read(&page->_count) != 0) |
- (page->flags & PAGE_FLAGS_CHECK_AT_FREE))) {
+ (page->flags & PAGE_FLAGS_CHECK_AT_FREE) |
+ (mem_cgroup_bad_page_check(page)))) {
bad_page(page);
return 1;
}
@@ -754,7 +756,8 @@
if (unlikely(page_mapcount(page) |
(page->mapping != NULL) |
(atomic_read(&page->_count) != 0) |
- (page->flags & PAGE_FLAGS_CHECK_AT_PREP))) {
+ (page->flags & PAGE_FLAGS_CHECK_AT_PREP) |
+ (mem_cgroup_bad_page_check(page)))) {
bad_page(page);
return 1;
}
@@ -5684,4 +5687,5 @@
page, atomic_read(&page->_count), page_mapcount(page),
page->mapping, page->index);
dump_page_flags(page->flags);
+ mem_cgroup_print_bad_page(page);
}