diff options
| -rw-r--r-- | mm/memcontrol.c | 53 |
1 files changed, 25 insertions, 28 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 04ded27f622..5b3759bd549 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -536,28 +536,6 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm, if (mem_cgroup_subsys.disabled) return 0; - /* - * Should page_cgroup's go to their own slab? - * One could optimize the performance of the charging routine - * by saving a bit in the page_flags and using it as a lock - * to see if the cgroup page already has a page_cgroup associated - * with it - */ -retry: - lock_page_cgroup(page); - pc = page_get_page_cgroup(page); - /* - * The page_cgroup exists and - * the page has already been accounted. - */ - if (unlikely(pc)) { - VM_BUG_ON(pc->page != page); - VM_BUG_ON(!pc->mem_cgroup); - unlock_page_cgroup(page); - goto done; - } - unlock_page_cgroup(page); - pc = kmem_cache_alloc(page_cgroup_cache, gfp_mask); if (unlikely(pc == NULL)) goto err; @@ -618,15 +596,10 @@ retry: lock_page_cgroup(page); if (unlikely(page_get_page_cgroup(page))) { unlock_page_cgroup(page); - /* - * Another charge has been added to this page already. - * We take lock_page_cgroup(page) again and read - * page->cgroup, increment refcnt.... just retry is OK. - */ res_counter_uncharge(&mem->res, PAGE_SIZE); css_put(&mem->css); kmem_cache_free(page_cgroup_cache, pc); - goto retry; + goto done; } page_assign_page_cgroup(page, pc); @@ -665,8 +638,32 @@ int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask) int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask) { + /* + * Corner case handling. This is called from add_to_page_cache() + * in usual. But some FS (shmem) precharges this page before calling it + * and call add_to_page_cache() with GFP_NOWAIT. + * + * For GFP_NOWAIT case, the page may be pre-charged before calling + * add_to_page_cache(). (See shmem.c) check it here and avoid to call + * charge twice. (It works but has to pay a bit larger cost.) + */ + if (!(gfp_mask & __GFP_WAIT)) { + struct page_cgroup *pc; + + lock_page_cgroup(page); + pc = page_get_page_cgroup(page); + if (pc) { + VM_BUG_ON(pc->page != page); + VM_BUG_ON(!pc->mem_cgroup); + unlock_page_cgroup(page); + return 0; + } + unlock_page_cgroup(page); + } + if (unlikely(!mm)) mm = &init_mm; + return mem_cgroup_charge_common(page, mm, gfp_mask, MEM_CGROUP_CHARGE_TYPE_CACHE, NULL); } |