diff options
author | KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> | 2011-01-25 18:07:29 -0500 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-01-25 19:50:04 -0500 |
commit | 52dbb9050936fd33ceb45f10529dbc992507c058 (patch) | |
tree | 1c3663f50b7dec0bd852b02d76095b9a5618d7b7 /mm | |
parent | 3d37c4a9199920964ffdfaec6335d93b9dcf9ca5 (diff) |
memcg: fix race at move_parent around compound_order()
A fix up mem_cgroup_move_parent() which use compound_order() in
asynchronous manner. This compound_order() may return unknown value
because we don't take lock. Use PageTransHuge() and HPAGE_SIZE instead
of it.
Also clean up for mem_cgroup_move_parent().
- remove unnecessary initialization of local variable.
- rename charge_size -> page_size
- remove unnecessary (wrong) comment.
- added a comment about THP.
Note:
Current design take compound_page_lock() in caller of move_account().
This should be revisited when we implement direct move_task of hugepage
without splitting.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/memcontrol.c | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 8ab1d42664f..3878cfe399d 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c | |||
@@ -2236,7 +2236,12 @@ static int mem_cgroup_move_account(struct page_cgroup *pc, | |||
2236 | { | 2236 | { |
2237 | int ret = -EINVAL; | 2237 | int ret = -EINVAL; |
2238 | unsigned long flags; | 2238 | unsigned long flags; |
2239 | 2239 | /* | |
2240 | * The page is isolated from LRU. So, collapse function | ||
2241 | * will not handle this page. But page splitting can happen. | ||
2242 | * Do this check under compound_page_lock(). The caller should | ||
2243 | * hold it. | ||
2244 | */ | ||
2240 | if ((charge_size > PAGE_SIZE) && !PageTransHuge(pc->page)) | 2245 | if ((charge_size > PAGE_SIZE) && !PageTransHuge(pc->page)) |
2241 | return -EBUSY; | 2246 | return -EBUSY; |
2242 | 2247 | ||
@@ -2268,7 +2273,7 @@ static int mem_cgroup_move_parent(struct page_cgroup *pc, | |||
2268 | struct cgroup *cg = child->css.cgroup; | 2273 | struct cgroup *cg = child->css.cgroup; |
2269 | struct cgroup *pcg = cg->parent; | 2274 | struct cgroup *pcg = cg->parent; |
2270 | struct mem_cgroup *parent; | 2275 | struct mem_cgroup *parent; |
2271 | int charge = PAGE_SIZE; | 2276 | int page_size = PAGE_SIZE; |
2272 | unsigned long flags; | 2277 | unsigned long flags; |
2273 | int ret; | 2278 | int ret; |
2274 | 2279 | ||
@@ -2281,22 +2286,24 @@ static int mem_cgroup_move_parent(struct page_cgroup *pc, | |||
2281 | goto out; | 2286 | goto out; |
2282 | if (isolate_lru_page(page)) | 2287 | if (isolate_lru_page(page)) |
2283 | goto put; | 2288 | goto put; |
2284 | /* The page is isolated from LRU and we have no race with splitting */ | 2289 | |
2285 | charge = PAGE_SIZE << compound_order(page); | 2290 | if (PageTransHuge(page)) |
2291 | page_size = HPAGE_SIZE; | ||
2286 | 2292 | ||
2287 | parent = mem_cgroup_from_cont(pcg); | 2293 | parent = mem_cgroup_from_cont(pcg); |
2288 | ret = __mem_cgroup_try_charge(NULL, gfp_mask, &parent, false, charge); | 2294 | ret = __mem_cgroup_try_charge(NULL, gfp_mask, |
2295 | &parent, false, page_size); | ||
2289 | if (ret || !parent) | 2296 | if (ret || !parent) |
2290 | goto put_back; | 2297 | goto put_back; |
2291 | 2298 | ||
2292 | if (charge > PAGE_SIZE) | 2299 | if (page_size > PAGE_SIZE) |
2293 | flags = compound_lock_irqsave(page); | 2300 | flags = compound_lock_irqsave(page); |
2294 | 2301 | ||
2295 | ret = mem_cgroup_move_account(pc, child, parent, true, charge); | 2302 | ret = mem_cgroup_move_account(pc, child, parent, true, page_size); |
2296 | if (ret) | 2303 | if (ret) |
2297 | mem_cgroup_cancel_charge(parent, charge); | 2304 | mem_cgroup_cancel_charge(parent, page_size); |
2298 | 2305 | ||
2299 | if (charge > PAGE_SIZE) | 2306 | if (page_size > PAGE_SIZE) |
2300 | compound_unlock_irqrestore(page, flags); | 2307 | compound_unlock_irqrestore(page, flags); |
2301 | put_back: | 2308 | put_back: |
2302 | putback_lru_page(page); | 2309 | putback_lru_page(page); |