On Mon, Jun 25, 2018 at 04:06:58PM -0700, Shakeel Butt wrote:
> @@ -140,8 +141,9 @@ struct fanotify_event_info *fanotify_alloc_event(struct fsnotify_group *group,
> struct inode *inode, u32 mask,
> const struct path *path)
> {
> - struct fanotify_event_info *event;
> + struct fanotify_event_info *event = NULL;
> gfp_t gfp = GFP_KERNEL;
> + struct mem_cgroup *old_memcg = NULL;
>
> /*
> * For queues with unlimited length lost events are not expected and
> @@ -151,19 +153,25 @@ struct fanotify_event_info *fanotify_alloc_event(struct fsnotify_group *group,
> if (group->max_events == UINT_MAX)
> gfp |= __GFP_NOFAIL;
>
> + /* Whoever is interested in the event, pays for the allocation. */
> + if (group->memcg) {
> + gfp |= __GFP_ACCOUNT;
> + old_memcg = memalloc_use_memcg(group->memcg);
> + }
group->memcg is only NULL when memcg is disabled or there is some
offlining race. Can you make memalloc_use_memcg(NULL) mean that it
should charge root_mem_cgroup instead of current->mm->memcg? That way
we can make this site unconditional while retaining the behavior:
gfp_t gfp = GFP_KERNEL | __GFP_ACCOUNT;
memalloc_use_memcg(group->memcg);
kmem_cache_alloc(..., gfp);
out:
memalloc_unuse_memcg();
(dropping old_memcg and the unuse parameter as per the other mail)
> if (fanotify_is_perm_event(mask)) {
> struct fanotify_perm_event_info *pevent;
>
> pevent = kmem_cache_alloc(fanotify_perm_event_cachep, gfp);
> if (!pevent)
> - return NULL;
> + goto out;
> event = &pevent->fae;
> pevent->response = 0;
> goto init;
> }
> event = kmem_cache_alloc(fanotify_event_cachep, gfp);
> if (!event)
> - return NULL;
> + goto out;
> init: __maybe_unused
> fsnotify_init_event(&event->fse, inode, mask);
> event->tgid = get_pid(task_tgid(current));
> @@ -174,6 +182,9 @@ init: __maybe_unused
> event->path.mnt = NULL;
> event->path.dentry = NULL;
> }
> +out:
> + if (group->memcg)
> + memalloc_unuse_memcg(old_memcg);
> return event;
> }
Thanks,
Johannes
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