Now, when THP is enabled, memcg's rmdir() function is broken
because move_account() for THP page is not supported.
This will cause account leak or -EBUSY issue at rmdir().
This patch fixes the issue by supporting move_account() THP pages.
And account information will be moved to its parent at rmdir().
How to test:
79 mount -t cgroup none /cgroup/memory/ -o memory
80 mkdir /cgroup/A/
81 mkdir /cgroup/memory/A
82 mkdir /cgroup/memory/A/B
83 cgexec -g memory:A/B ./malloc 128 &
84 grep anon /cgroup/memory/A/B/memory.stat
85 grep rss /cgroup/memory/A/B/memory.stat
86 echo 1728 > /cgroup/memory/A/tasks
87 grep rss /cgroup/memory/A/memory.stat
88 rmdir /cgroup/memory/A/B/
89 grep rss /cgroup/memory/A/memory.stat
- Create 2 level directory and exec a task calls malloc(big chunk).
- Move a task somewhere (its parent cgroup in above)
- rmdir /A/B
- check memory.stat in /A/B is moved to /A after rmdir. and confirm
RSS/LRU information includes usages it was charged against /A/B.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
---
mm/memcontrol.c | 32 ++++++++++++++++++++++----------
1 file changed, 22 insertions(+), 10 deletions(-)
Index: mmotm-0107/mm/memcontrol.c
===================================================================
--- mmotm-0107.orig/mm/memcontrol.c
+++ mmotm-0107/mm/memcontrol.c
@@ -2154,6 +2154,10 @@ void mem_cgroup_split_huge_fixup(struct
smp_wmb(); /* see __commit_charge() */
SetPageCgroupUsed(tpc);
VM_BUG_ON(PageCgroupCache(hpc));
+ /*
+ * Note: if dirty ratio etc..are supported,
+ * other flags may need to be copied.
+ */
}
#endif
@@ -2175,8 +2179,11 @@ void mem_cgroup_split_huge_fixup(struct
*/
static void __mem_cgroup_move_account(struct page_cgroup *pc,
- struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge)
+ struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge,
+ int charge_size)
{
+ int pagenum = charge_size >> PAGE_SHIFT;
+
VM_BUG_ON(from == to);
VM_BUG_ON(PageLRU(pc->page));
VM_BUG_ON(!page_is_cgroup_locked(pc));
@@ -2190,14 +2197,14 @@ static void __mem_cgroup_move_account(st
__this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
preempt_enable();
}
- mem_cgroup_charge_statistics(from, PageCgroupCache(pc), -1);
+ mem_cgroup_charge_statistics(from, PageCgroupCache(pc), -pagenum);
if (uncharge)
/* This is not "cancel", but cancel_charge does all we need. */
- mem_cgroup_cancel_charge(from, PAGE_SIZE);
+ mem_cgroup_cancel_charge(from, charge_size);
/* caller should have done css_get */
pc->mem_cgroup = to;
- mem_cgroup_charge_statistics(to, PageCgroupCache(pc), 1);
+ mem_cgroup_charge_statistics(to, PageCgroupCache(pc), pagenum);
/*
* We charges against "to" which may not have any tasks. Then, "to"
* can be under rmdir(). But in current implementation, caller of
@@ -2212,7 +2219,8 @@ static void __mem_cgroup_move_account(st
* __mem_cgroup_move_account()
*/
static int mem_cgroup_move_account(struct page_cgroup *pc,
- struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge)
+ struct mem_cgroup *from, struct mem_cgroup *to,
+ bool uncharge, int charge_size)
{
int ret = -EINVAL;
unsigned long flags;
@@ -2220,7 +2228,7 @@ static int mem_cgroup_move_account(struc
lock_page_cgroup(pc);
if (PageCgroupUsed(pc) && pc->mem_cgroup == from) {
move_lock_page_cgroup(pc, &flags);
- __mem_cgroup_move_account(pc, from, to, uncharge);
+ __mem_cgroup_move_account(pc, from, to, uncharge, charge_size);
move_unlock_page_cgroup(pc, &flags);
ret = 0;
}
@@ -2245,6 +2253,7 @@ static int mem_cgroup_move_parent(struct
struct cgroup *cg = child->css.cgroup;
struct cgroup *pcg = cg->parent;
struct mem_cgroup *parent;
+ int charge_size = PAGE_SIZE;
int ret;
/* Is ROOT ? */
@@ -2256,16 +2265,19 @@ static int mem_cgroup_move_parent(struct
goto out;
if (isolate_lru_page(page))
goto put;
+ /* The page is isolated from LRU and we have no race with splitting */
+ if (PageTransHuge(page))
+ charge_size = PAGE_SIZE << compound_order(page);
parent = mem_cgroup_from_cont(pcg);
ret = __mem_cgroup_try_charge(NULL, gfp_mask, &parent, false,
- PAGE_SIZE);
+ charge_size);
if (ret || !parent)
goto put_back;
- ret = mem_cgroup_move_account(pc, child, parent, true);
+ ret = mem_cgroup_move_account(pc, child, parent, true, charge_size);
if (ret)
- mem_cgroup_cancel_charge(parent, PAGE_SIZE);
+ mem_cgroup_cancel_charge(parent, charge_size);
put_back:
putback_lru_page(page);
put:
@@ -4850,7 +4862,7 @@ retry:
goto put;
pc = lookup_page_cgroup(page);
if (!mem_cgroup_move_account(pc,
- mc.from, mc.to, false)) {
+ mc.from, mc.to, false, PAGE_SIZE)) {
mc.precharge--;
/* we uncharge from mc.from later. */
mc.moved_charge++;
--
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