From 2ae928a9441a3b5f13952e1e8a97d03cb23ea603 Mon Sep 17 00:00:00 2001 From: Shakeel Butt Date: Fri, 17 Nov 2017 15:28:59 -0800 Subject: epoll: account epitem and eppoll_entry to kmemcg A userspace application can directly trigger the allocations from eventpoll_epi and eventpoll_pwq slabs. A buggy or malicious application can consume a significant amount of system memory by triggering such allocations. Indeed we have seen in production where a buggy application was leaking the epoll references and causing a burst of eventpoll_epi and eventpoll_pwq slab allocations. This patch opt-in the charging of eventpoll_epi and eventpoll_pwq slabs. There is a per-user limit (~4% of total memory if no highmem) on these caches. I think it is too generous particularly in the scenario where jobs of multiple users are running on the system and the administrator is reducing cost by overcomitting the memory. This is unaccounted kernel memory and will not be considered by the oom-killer. I think by accounting it to kmemcg, for systems with kmem accounting enabled, we can provide better isolation between jobs of different users. Link: http://lkml.kernel.org/r/20171003021519.23907-1-shakeelb@google.com Signed-off-by: Shakeel Butt Acked-by: Michal Hocko Cc: Alexander Viro Cc: Vladimir Davydov Cc: Johannes Weiner Cc: Greg Thelen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/eventpoll.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'fs') diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 2fabd19..a453604 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -2329,11 +2329,11 @@ static int __init eventpoll_init(void) /* Allocates slab cache used to allocate "struct epitem" items */ epi_cache = kmem_cache_create("eventpoll_epi", sizeof(struct epitem), - 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); + 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL); /* Allocates slab cache used to allocate "struct eppoll_entry" */ pwq_cache = kmem_cache_create("eventpoll_pwq", - sizeof(struct eppoll_entry), 0, SLAB_PANIC, NULL); + sizeof(struct eppoll_entry), 0, SLAB_PANIC|SLAB_ACCOUNT, NULL); return 0; } -- cgit v1.1