diff options
Diffstat (limited to 'mm/mmap_lock.c')
| -rw-r--r-- | mm/mmap_lock.c | 208 |
1 files changed, 3 insertions, 205 deletions
diff --git a/mm/mmap_lock.c b/mm/mmap_lock.c index 1854850b4b89..e7dbaf96aa17 100644 --- a/mm/mmap_lock.c +++ b/mm/mmap_lock.c @@ -17,209 +17,7 @@ EXPORT_TRACEPOINT_SYMBOL(mmap_lock_start_locking); EXPORT_TRACEPOINT_SYMBOL(mmap_lock_acquire_returned); EXPORT_TRACEPOINT_SYMBOL(mmap_lock_released); -#ifdef CONFIG_MEMCG - -/* - * Our various events all share the same buffer (because we don't want or need - * to allocate a set of buffers *per event type*), so we need to protect against - * concurrent _reg() and _unreg() calls, and count how many _reg() calls have - * been made. - */ -static DEFINE_MUTEX(reg_lock); -static int reg_refcount; /* Protected by reg_lock. */ - -/* - * Size of the buffer for memcg path names. Ignoring stack trace support, - * trace_events_hist.c uses MAX_FILTER_STR_VAL for this, so we also use it. - */ -#define MEMCG_PATH_BUF_SIZE MAX_FILTER_STR_VAL - -/* - * How many contexts our trace events might be called in: normal, softirq, irq, - * and NMI. - */ -#define CONTEXT_COUNT 4 - -struct memcg_path { - local_lock_t lock; - char __rcu *buf; - local_t buf_idx; -}; -static DEFINE_PER_CPU(struct memcg_path, memcg_paths) = { - .lock = INIT_LOCAL_LOCK(lock), - .buf_idx = LOCAL_INIT(0), -}; - -static char **tmp_bufs; - -/* Called with reg_lock held. */ -static void free_memcg_path_bufs(void) -{ - struct memcg_path *memcg_path; - int cpu; - char **old = tmp_bufs; - - for_each_possible_cpu(cpu) { - memcg_path = per_cpu_ptr(&memcg_paths, cpu); - *(old++) = rcu_dereference_protected(memcg_path->buf, - lockdep_is_held(®_lock)); - rcu_assign_pointer(memcg_path->buf, NULL); - } - - /* Wait for inflight memcg_path_buf users to finish. */ - synchronize_rcu(); - - old = tmp_bufs; - for_each_possible_cpu(cpu) { - kfree(*(old++)); - } - - kfree(tmp_bufs); - tmp_bufs = NULL; -} - -int trace_mmap_lock_reg(void) -{ - int cpu; - char *new; - - mutex_lock(®_lock); - - /* If the refcount is going 0->1, proceed with allocating buffers. */ - if (reg_refcount++) - goto out; - - tmp_bufs = kmalloc_array(num_possible_cpus(), sizeof(*tmp_bufs), - GFP_KERNEL); - if (tmp_bufs == NULL) - goto out_fail; - - for_each_possible_cpu(cpu) { - new = kmalloc(MEMCG_PATH_BUF_SIZE * CONTEXT_COUNT, GFP_KERNEL); - if (new == NULL) - goto out_fail_free; - rcu_assign_pointer(per_cpu_ptr(&memcg_paths, cpu)->buf, new); - /* Don't need to wait for inflights, they'd have gotten NULL. */ - } - -out: - mutex_unlock(®_lock); - return 0; - -out_fail_free: - free_memcg_path_bufs(); -out_fail: - /* Since we failed, undo the earlier ref increment. */ - --reg_refcount; - - mutex_unlock(®_lock); - return -ENOMEM; -} - -void trace_mmap_lock_unreg(void) -{ - mutex_lock(®_lock); - - /* If the refcount is going 1->0, proceed with freeing buffers. */ - if (--reg_refcount) - goto out; - - free_memcg_path_bufs(); - -out: - mutex_unlock(®_lock); -} - -static inline char *get_memcg_path_buf(void) -{ - struct memcg_path *memcg_path = this_cpu_ptr(&memcg_paths); - char *buf; - int idx; - - rcu_read_lock(); - buf = rcu_dereference(memcg_path->buf); - if (buf == NULL) { - rcu_read_unlock(); - return NULL; - } - idx = local_add_return(MEMCG_PATH_BUF_SIZE, &memcg_path->buf_idx) - - MEMCG_PATH_BUF_SIZE; - return &buf[idx]; -} - -static inline void put_memcg_path_buf(void) -{ - local_sub(MEMCG_PATH_BUF_SIZE, &this_cpu_ptr(&memcg_paths)->buf_idx); - rcu_read_unlock(); -} - -#define TRACE_MMAP_LOCK_EVENT(type, mm, ...) \ - do { \ - const char *memcg_path; \ - local_lock(&memcg_paths.lock); \ - memcg_path = get_mm_memcg_path(mm); \ - trace_mmap_lock_##type(mm, \ - memcg_path != NULL ? memcg_path : "", \ - ##__VA_ARGS__); \ - if (likely(memcg_path != NULL)) \ - put_memcg_path_buf(); \ - local_unlock(&memcg_paths.lock); \ - } while (0) - -#else /* !CONFIG_MEMCG */ - -int trace_mmap_lock_reg(void) -{ - return 0; -} - -void trace_mmap_lock_unreg(void) -{ -} - -#define TRACE_MMAP_LOCK_EVENT(type, mm, ...) \ - trace_mmap_lock_##type(mm, "", ##__VA_ARGS__) - -#endif /* CONFIG_MEMCG */ - #ifdef CONFIG_TRACING -#ifdef CONFIG_MEMCG -/* - * Write the given mm_struct's memcg path to a percpu buffer, and return a - * pointer to it. If the path cannot be determined, or no buffer was available - * (because the trace event is being unregistered), NULL is returned. - * - * Note: buffers are allocated per-cpu to avoid locking, so preemption must be - * disabled by the caller before calling us, and re-enabled only after the - * caller is done with the pointer. - * - * The caller must call put_memcg_path_buf() once the buffer is no longer - * needed. This must be done while preemption is still disabled. - */ -static const char *get_mm_memcg_path(struct mm_struct *mm) -{ - char *buf = NULL; - struct mem_cgroup *memcg = get_mem_cgroup_from_mm(mm); - - if (memcg == NULL) - goto out; - if (unlikely(memcg->css.cgroup == NULL)) - goto out_put; - - buf = get_memcg_path_buf(); - if (buf == NULL) - goto out_put; - - cgroup_path(memcg->css.cgroup, buf, MEMCG_PATH_BUF_SIZE); - -out_put: - css_put(&memcg->css); -out: - return buf; -} - -#endif /* CONFIG_MEMCG */ - /* * Trace calls must be in a separate file, as otherwise there's a circular * dependency between linux/mmap_lock.h and trace/events/mmap_lock.h. @@ -227,20 +25,20 @@ out: void __mmap_lock_do_trace_start_locking(struct mm_struct *mm, bool write) { - TRACE_MMAP_LOCK_EVENT(start_locking, mm, write); + trace_mmap_lock_start_locking(mm, write); } EXPORT_SYMBOL(__mmap_lock_do_trace_start_locking); void __mmap_lock_do_trace_acquire_returned(struct mm_struct *mm, bool write, bool success) { - TRACE_MMAP_LOCK_EVENT(acquire_returned, mm, write, success); + trace_mmap_lock_acquire_returned(mm, write, success); } EXPORT_SYMBOL(__mmap_lock_do_trace_acquire_returned); void __mmap_lock_do_trace_released(struct mm_struct *mm, bool write) { - TRACE_MMAP_LOCK_EVENT(released, mm, write); + trace_mmap_lock_released(mm, write); } EXPORT_SYMBOL(__mmap_lock_do_trace_released); #endif /* CONFIG_TRACING */ |