On Tue 20-02-18 19:01:01, Shakeel Butt wrote: > A lot of memory can be consumed by the events generated for the huge or > unlimited queues if there is either no or slow listener. This can cause > system level memory pressure or OOMs. So, it's better to account the > fsnotify kmem caches to the memcg of the listener. How much memory are we talking about here? > There are seven fsnotify kmem caches and among them allocations from > dnotify_struct_cache, dnotify_mark_cache, fanotify_mark_cache and > inotify_inode_mark_cachep happens in the context of syscall from the > listener. So, SLAB_ACCOUNT is enough for these caches. > > The objects from fsnotify_mark_connector_cachep are not accounted as > they are small compared to the notification mark or events and it is > unclear whom to account connector to since it is shared by all events > attached to the inode. > > The allocations from the event caches happen in the context of the event > producer. For such caches we will need to remote charge the allocations > to the listener's memcg. Thus we save the memcg reference in the > fsnotify_group structure of the listener. Is it typical that the listener lives in a different memcg and if yes then cannot this cause one memcg to OOM/DoS the one with the listener? > This patch has also moved the members of fsnotify_group to keep the > size same, at least for 64 bit build, even with additional member by > filling the holes. > > Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx> [...] -- Michal Hocko SUSE Labs
