struct oom_control oc = {
.zonelist = NULL,
.nodemask = NULL,
+ .memcg = memcg,
.gfp_mask = gfp_mask,
.order = order,
};
goto unlock;
}
- check_panic_on_oom(&oc, CONSTRAINT_MEMCG, memcg);
+ check_panic_on_oom(&oc, CONSTRAINT_MEMCG);
totalpages = mem_cgroup_get_limit(memcg) ? : 1;
for_each_mem_cgroup_tree(iter, memcg) {
struct css_task_iter it;
if (chosen) {
points = chosen_points * 1000 / totalpages;
- oom_kill_process(&oc, chosen, points, totalpages, memcg,
+ oom_kill_process(&oc, chosen, points, totalpages,
"Memory cgroup out of memory");
}
unlock:
current->memcg_kmem_skip_account = 0;
}
-/*
+static inline bool memcg_kmem_bypass(void)
+{
+ if (in_interrupt() || !current->mm || (current->flags & PF_KTHREAD))
+ return true;
+ return false;
+}
+
+/**
+ * memcg_kmem_get_cache: select the correct per-memcg cache for allocation
+ * @cachep: the original global kmem cache
+ *
* Return the kmem_cache we're supposed to use for a slab allocation.
* We try to use the current memcg's version of the cache.
*
- * If the cache does not exist yet, if we are the first user of it,
- * we either create it immediately, if possible, or create it asynchronously
- * in a workqueue.
- * In the latter case, we will let the current allocation go through with
- * the original cache.
+ * If the cache does not exist yet, if we are the first user of it, we
+ * create it asynchronously in a workqueue and let the current allocation
+ * go through with the original cache.
*
- * Can't be called in interrupt context or from kernel threads.
- * This function needs to be called with rcu_read_lock() held.
+ * This function takes a reference to the cache it returns to assure it
+ * won't get destroyed while we are working with it. Once the caller is
+ * done with it, memcg_kmem_put_cache() must be called to release the
+ * reference.
*/
-struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp)
+struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep)
{
struct mem_cgroup *memcg;
struct kmem_cache *memcg_cachep;
VM_BUG_ON(!is_root_cache(cachep));
- if (cachep->flags & SLAB_ACCOUNT)
- gfp |= __GFP_ACCOUNT;
-
- if (!(gfp & __GFP_ACCOUNT))
+ if (memcg_kmem_bypass())
return cachep;
if (current->memcg_kmem_skip_account)
return cachep;
}
-void __memcg_kmem_put_cache(struct kmem_cache *cachep)
+/**
+ * memcg_kmem_put_cache: drop reference taken by memcg_kmem_get_cache
+ * @cachep: the cache returned by memcg_kmem_get_cache
+ */
+void memcg_kmem_put_cache(struct kmem_cache *cachep)
{
if (!is_root_cache(cachep))
css_put(&cachep->memcg_params.memcg->css);
}
-int __memcg_kmem_charge_memcg(struct page *page, gfp_t gfp, int order,
- struct mem_cgroup *memcg)
+/**
+ * memcg_kmem_charge: charge a kmem page
+ * @page: page to charge
+ * @gfp: reclaim mode
+ * @order: allocation order
+ * @memcg: memory cgroup to charge
+ *
+ * Returns 0 on success, an error code on failure.
+ */
+int memcg_kmem_charge_memcg(struct page *page, gfp_t gfp, int order,
+ struct mem_cgroup *memcg)
{
unsigned int nr_pages = 1 << order;
struct page_counter *counter;
return 0;
}
-int __memcg_kmem_charge(struct page *page, gfp_t gfp, int order)
+/**
+ * memcg_kmem_charge: charge a kmem page to the current memory cgroup
+ * @page: page to charge
+ * @gfp: reclaim mode
+ * @order: allocation order
+ *
+ * Returns 0 on success, an error code on failure.
+ */
+int memcg_kmem_charge(struct page *page, gfp_t gfp, int order)
{
struct mem_cgroup *memcg;
int ret = 0;
+ if (memcg_kmem_bypass())
+ return 0;
+
memcg = get_mem_cgroup_from_mm(current->mm);
if (!mem_cgroup_is_root(memcg))
- ret = __memcg_kmem_charge_memcg(page, gfp, order, memcg);
+ ret = memcg_kmem_charge_memcg(page, gfp, order, memcg);
css_put(&memcg->css);
return ret;
}
-
-void __memcg_kmem_uncharge(struct page *page, int order)
+/**
+ * memcg_kmem_uncharge: uncharge a kmem page
+ * @page: page to uncharge
+ * @order: allocation order
+ */
+void memcg_kmem_uncharge(struct page *page, int order)
{
struct mem_cgroup *memcg = page->mem_cgroup;
unsigned int nr_pages = 1 << order;
{ }, /* terminate */
};
+/*
+ * Private memory cgroup IDR
+ *
+ * Swap-out records and page cache shadow entries need to store memcg
+ * references in constrained space, so we maintain an ID space that is
+ * limited to 16 bit (MEM_CGROUP_ID_MAX), limiting the total number of
+ * memory-controlled cgroups to 64k.
+ *
+ * However, there usually are many references to the oflline CSS after
+ * the cgroup has been destroyed, such as page cache or reclaimable
+ * slab objects, that don't need to hang on to the ID. We want to keep
+ * those dead CSS from occupying IDs, or we might quickly exhaust the
+ * relatively small ID space and prevent the creation of new cgroups
+ * even when there are much fewer than 64k cgroups - possibly none.
+ *
+ * Maintain a private 16-bit ID space for memcg, and allow the ID to
+ * be freed and recycled when it's no longer needed, which is usually
+ * when the CSS is offlined.
+ *
+ * The only exception to that are records of swapped out tmpfs/shmem
+ * pages that need to be attributed to live ancestors on swapin. But
+ * those references are manageable from userspace.
+ */
+
+static DEFINE_IDR(mem_cgroup_idr);
+
+static void mem_cgroup_id_get(struct mem_cgroup *memcg)
+{
+ atomic_inc(&memcg->id.ref);
+}
+
+static void mem_cgroup_id_put(struct mem_cgroup *memcg)
+{
+ if (atomic_dec_and_test(&memcg->id.ref)) {
+ idr_remove(&mem_cgroup_idr, memcg->id.id);
+ memcg->id.id = 0;
+
+ /* Memcg ID pins CSS */
+ css_put(&memcg->css);
+ }
+}
+
+/**
+ * mem_cgroup_from_id - look up a memcg from a memcg id
+ * @id: the memcg id to look up
+ *
+ * Caller must hold rcu_read_lock().
+ */
+struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
+{
+ WARN_ON_ONCE(!rcu_read_lock_held());
+ return idr_find(&mem_cgroup_idr, id);
+}
+
static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
{
struct mem_cgroup_per_node *pn;
if (!memcg)
return NULL;
+ memcg->id.id = idr_alloc(&mem_cgroup_idr, NULL,
+ 1, MEM_CGROUP_ID_MAX,
+ GFP_KERNEL);
+ if (memcg->id.id < 0)
+ goto fail;
+
memcg->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
if (!memcg->stat)
goto fail;
#ifdef CONFIG_CGROUP_WRITEBACK
INIT_LIST_HEAD(&memcg->cgwb_list);
#endif
+ idr_replace(&mem_cgroup_idr, memcg, memcg->id.id);
return memcg;
fail:
+ if (memcg->id.id > 0)
+ idr_remove(&mem_cgroup_idr, memcg->id.id);
mem_cgroup_free(memcg);
return NULL;
}
return ERR_PTR(-ENOMEM);
}
-static int
-mem_cgroup_css_online(struct cgroup_subsys_state *css)
+static int mem_cgroup_css_online(struct cgroup_subsys_state *css)
{
- if (css->id > MEM_CGROUP_ID_MAX)
- return -ENOSPC;
-
+ /* Online state pins memcg ID, memcg ID pins CSS */
+ mem_cgroup_id_get(mem_cgroup_from_css(css));
+ css_get(css);
return 0;
}
memcg_offline_kmem(memcg);
wb_memcg_offline(memcg);
+
+ mem_cgroup_id_put(memcg);
}
static void mem_cgroup_css_released(struct cgroup_subsys_state *css)
#ifdef CONFIG_SWAP
static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
- unsigned long addr, pte_t ptent, swp_entry_t *entry)
+ pte_t ptent, swp_entry_t *entry)
{
struct page *page = NULL;
swp_entry_t ent = pte_to_swp_entry(ptent);
}
#else
static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
- unsigned long addr, pte_t ptent, swp_entry_t *entry)
+ pte_t ptent, swp_entry_t *entry)
{
return NULL;
}
if (pte_present(ptent))
page = mc_handle_present_pte(vma, addr, ptent);
else if (is_swap_pte(ptent))
- page = mc_handle_swap_pte(vma, addr, ptent, &ent);
+ page = mc_handle_swap_pte(vma, ptent, &ent);
else if (pte_none(ptent))
page = mc_handle_file_pte(vma, addr, ptent, &ent);
if (!memcg)
return;
+ mem_cgroup_id_get(memcg);
oldid = swap_cgroup_record(entry, mem_cgroup_id(memcg));
VM_BUG_ON_PAGE(oldid, page);
mem_cgroup_swap_statistics(memcg, true);
VM_BUG_ON(!irqs_disabled());
mem_cgroup_charge_statistics(memcg, page, false, -1);
memcg_check_events(memcg, page);
+
+ if (!mem_cgroup_is_root(memcg))
+ css_put(&memcg->css);
}
/*
!page_counter_try_charge(&memcg->swap, 1, &counter))
return -ENOMEM;
+ mem_cgroup_id_get(memcg);
oldid = swap_cgroup_record(entry, mem_cgroup_id(memcg));
VM_BUG_ON_PAGE(oldid, page);
mem_cgroup_swap_statistics(memcg, true);
- css_get(&memcg->css);
return 0;
}
page_counter_uncharge(&memcg->memsw, 1);
}
mem_cgroup_swap_statistics(memcg, false);
- css_put(&memcg->css);
+ mem_cgroup_id_put(memcg);
}
rcu_read_unlock();
}