diff options
| author | Roman Gushchin <roman.gushchin@linux.dev> | 2024-06-24 17:59:00 -0700 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-07-04 18:05:53 -0700 |
| commit | 292fc2e0204aa02a24f6d2684d71801068fec803 (patch) | |
| tree | 505b4d81271bb9e8f12b7751599ba3968757bbd9 /mm/memcontrol-v1.c | |
| parent | cc7b8504f624157c9be7aea9c9a9d5010fd908c9 (diff) | |
| download | lwn-292fc2e0204aa02a24f6d2684d71801068fec803.tar.gz lwn-292fc2e0204aa02a24f6d2684d71801068fec803.zip | |
mm: memcg: move cgroup v1 oom handling code into memcontrol-v1.c
Cgroup v1 supports a complicated OOM handling in userspace mechanism,
which is not supported by cgroup v2. Let's move the corresponding code
into memcontrol-v1.c.
Aside from mechanical code movement this patch introduces two new
functions: memcg1_oom_prepare() and memcg1_oom_finish(). Those are
implementing cgroup v1-specific parts of the common memcg OOM handling
path.
Link: https://lkml.kernel.org/r/20240625005906.106920-9-roman.gushchin@linux.dev
Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/memcontrol-v1.c')
| -rw-r--r-- | mm/memcontrol-v1.c | 229 |
1 files changed, 227 insertions, 2 deletions
diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c index d7b5c4c14732..253d49d5fb12 100644 --- a/mm/memcontrol-v1.c +++ b/mm/memcontrol-v1.c @@ -110,7 +110,13 @@ struct mem_cgroup_event { struct work_struct remove; }; -extern spinlock_t memcg_oom_lock; +#ifdef CONFIG_LOCKDEP +static struct lockdep_map memcg_oom_lock_dep_map = { + .name = "memcg_oom_lock", +}; +#endif + +DEFINE_SPINLOCK(memcg_oom_lock); static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_node *mz, struct mem_cgroup_tree_per_node *mctz, @@ -1469,7 +1475,7 @@ static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg) return 0; } -void mem_cgroup_oom_notify(struct mem_cgroup *memcg) +static void mem_cgroup_oom_notify(struct mem_cgroup *memcg) { struct mem_cgroup *iter; @@ -1959,6 +1965,225 @@ void memcg1_css_offline(struct mem_cgroup *memcg) spin_unlock_irq(&memcg->event_list_lock); } +/* + * Check OOM-Killer is already running under our hierarchy. + * If someone is running, return false. + */ +static bool mem_cgroup_oom_trylock(struct mem_cgroup *memcg) +{ + struct mem_cgroup *iter, *failed = NULL; + + spin_lock(&memcg_oom_lock); + + for_each_mem_cgroup_tree(iter, memcg) { + if (iter->oom_lock) { + /* + * this subtree of our hierarchy is already locked + * so we cannot give a lock. + */ + failed = iter; + mem_cgroup_iter_break(memcg, iter); + break; + } else + iter->oom_lock = true; + } + + if (failed) { + /* + * OK, we failed to lock the whole subtree so we have + * to clean up what we set up to the failing subtree + */ + for_each_mem_cgroup_tree(iter, memcg) { + if (iter == failed) { + mem_cgroup_iter_break(memcg, iter); + break; + } + iter->oom_lock = false; + } + } else + mutex_acquire(&memcg_oom_lock_dep_map, 0, 1, _RET_IP_); + + spin_unlock(&memcg_oom_lock); + + return !failed; +} + +static void mem_cgroup_oom_unlock(struct mem_cgroup *memcg) +{ + struct mem_cgroup *iter; + + spin_lock(&memcg_oom_lock); + mutex_release(&memcg_oom_lock_dep_map, _RET_IP_); + for_each_mem_cgroup_tree(iter, memcg) + iter->oom_lock = false; + spin_unlock(&memcg_oom_lock); +} + +static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg) +{ + struct mem_cgroup *iter; + + spin_lock(&memcg_oom_lock); + for_each_mem_cgroup_tree(iter, memcg) + iter->under_oom++; + spin_unlock(&memcg_oom_lock); +} + +static void mem_cgroup_unmark_under_oom(struct mem_cgroup *memcg) +{ + struct mem_cgroup *iter; + + /* + * Be careful about under_oom underflows because a child memcg + * could have been added after mem_cgroup_mark_under_oom. + */ + spin_lock(&memcg_oom_lock); + for_each_mem_cgroup_tree(iter, memcg) + if (iter->under_oom > 0) + iter->under_oom--; + spin_unlock(&memcg_oom_lock); +} + +static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq); + +struct oom_wait_info { + struct mem_cgroup *memcg; + wait_queue_entry_t wait; +}; + +static int memcg_oom_wake_function(wait_queue_entry_t *wait, + unsigned mode, int sync, void *arg) +{ + struct mem_cgroup *wake_memcg = (struct mem_cgroup *)arg; + struct mem_cgroup *oom_wait_memcg; + struct oom_wait_info *oom_wait_info; + + oom_wait_info = container_of(wait, struct oom_wait_info, wait); + oom_wait_memcg = oom_wait_info->memcg; + + if (!mem_cgroup_is_descendant(wake_memcg, oom_wait_memcg) && + !mem_cgroup_is_descendant(oom_wait_memcg, wake_memcg)) + return 0; + return autoremove_wake_function(wait, mode, sync, arg); +} + +void memcg_oom_recover(struct mem_cgroup *memcg) +{ + /* + * For the following lockless ->under_oom test, the only required + * guarantee is that it must see the state asserted by an OOM when + * this function is called as a result of userland actions + * triggered by the notification of the OOM. This is trivially + * achieved by invoking mem_cgroup_mark_under_oom() before + * triggering notification. + */ + if (memcg && memcg->under_oom) + __wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg); +} + +/** + * mem_cgroup_oom_synchronize - complete memcg OOM handling + * @handle: actually kill/wait or just clean up the OOM state + * + * This has to be called at the end of a page fault if the memcg OOM + * handler was enabled. + * + * Memcg supports userspace OOM handling where failed allocations must + * sleep on a waitqueue until the userspace task resolves the + * situation. Sleeping directly in the charge context with all kinds + * of locks held is not a good idea, instead we remember an OOM state + * in the task and mem_cgroup_oom_synchronize() has to be called at + * the end of the page fault to complete the OOM handling. + * + * Returns %true if an ongoing memcg OOM situation was detected and + * completed, %false otherwise. + */ +bool mem_cgroup_oom_synchronize(bool handle) +{ + struct mem_cgroup *memcg = current->memcg_in_oom; + struct oom_wait_info owait; + bool locked; + + /* OOM is global, do not handle */ + if (!memcg) + return false; + + if (!handle) + goto cleanup; + + owait.memcg = memcg; + owait.wait.flags = 0; + owait.wait.func = memcg_oom_wake_function; + owait.wait.private = current; + INIT_LIST_HEAD(&owait.wait.entry); + + prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE); + mem_cgroup_mark_under_oom(memcg); + + locked = mem_cgroup_oom_trylock(memcg); + + if (locked) + mem_cgroup_oom_notify(memcg); + + schedule(); + mem_cgroup_unmark_under_oom(memcg); + finish_wait(&memcg_oom_waitq, &owait.wait); + + if (locked) + mem_cgroup_oom_unlock(memcg); +cleanup: + current->memcg_in_oom = NULL; + css_put(&memcg->css); + return true; +} + + +bool memcg1_oom_prepare(struct mem_cgroup *memcg, bool *locked) +{ + /* + * We are in the middle of the charge context here, so we + * don't want to block when potentially sitting on a callstack + * that holds all kinds of filesystem and mm locks. + * + * cgroup1 allows disabling the OOM killer and waiting for outside + * handling until the charge can succeed; remember the context and put + * the task to sleep at the end of the page fault when all locks are + * released. + * + * On the other hand, in-kernel OOM killer allows for an async victim + * memory reclaim (oom_reaper) and that means that we are not solely + * relying on the oom victim to make a forward progress and we can + * invoke the oom killer here. + * + * Please note that mem_cgroup_out_of_memory might fail to find a + * victim and then we have to bail out from the charge path. + */ + if (READ_ONCE(memcg->oom_kill_disable)) { + if (current->in_user_fault) { + css_get(&memcg->css); + current->memcg_in_oom = memcg; + } + return false; + } + + mem_cgroup_mark_under_oom(memcg); + + *locked = mem_cgroup_oom_trylock(memcg); + + if (*locked) + mem_cgroup_oom_notify(memcg); + + mem_cgroup_unmark_under_oom(memcg); + + return true; +} + +void memcg1_oom_finish(struct mem_cgroup *memcg, bool locked) +{ + if (locked) + mem_cgroup_oom_unlock(memcg); +} + static int __init memcg1_init(void) { int node; |