Commit f212ad7c authored by Daisuke Nishimura's avatar Daisuke Nishimura Committed by Linus Torvalds
Browse files

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: default avatarDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent af4a6621

include/linux/memcontrol.h

+17 −0
Original line number Diff line number Diff line
@@ -151,6 +151,10 @@ u64 mem_cgroup_get_limit(struct mem_cgroup *mem); 
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 @@ static inline void mem_cgroup_split_huge_fixup(struct page *head, 


#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 */

mm/memcontrol.c

+46 −0
Original line number Diff line number Diff line
@@ -3046,6 +3046,52 @@ int mem_cgroup_shmem_charge_fallback(struct page *page, 
	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,

mm/page_alloc.c

+6 −2
Original line number Diff line number Diff line
@@ -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 @@ static inline int free_pages_check(struct page *page) 
	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 @@ static inline int check_new_page(struct page *page) 
	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 @@ void dump_page(struct page *page) 
		page, atomic_read(&page->_count), page_mapcount(page),

		page->mapping, page->index);

	dump_page_flags(page->flags);

	mem_cgroup_print_bad_page(page);

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE