From 6ad3122a08e3a9c2148873665752e87cf4f393cc Mon Sep 17 00:00:00 2001 From: Steffen Klassert Date: Mon, 22 Feb 2016 10:40:07 +0100 Subject: flowcache: Avoid OOM condition under preasure We can hit an OOM condition if we are under presure because we can not free the entries in gc_list fast enough. So add a counter for the not yet freed entries in the gc_list and refuse new allocations if the value is too high. Signed-off-by: Steffen Klassert --- net/core/flow.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) (limited to 'net/core') diff --git a/net/core/flow.c b/net/core/flow.c index 1033725be40b..3937b1b68d5b 100644 --- a/net/core/flow.c +++ b/net/core/flow.c @@ -92,8 +92,11 @@ static void flow_cache_gc_task(struct work_struct *work) list_splice_tail_init(&xfrm->flow_cache_gc_list, &gc_list); spin_unlock_bh(&xfrm->flow_cache_gc_lock); - list_for_each_entry_safe(fce, n, &gc_list, u.gc_list) + list_for_each_entry_safe(fce, n, &gc_list, u.gc_list) { flow_entry_kill(fce, xfrm); + atomic_dec(&xfrm->flow_cache_gc_count); + WARN_ON(atomic_read(&xfrm->flow_cache_gc_count) < 0); + } } static void flow_cache_queue_garbage(struct flow_cache_percpu *fcp, @@ -101,6 +104,7 @@ static void flow_cache_queue_garbage(struct flow_cache_percpu *fcp, struct netns_xfrm *xfrm) { if (deleted) { + atomic_add(deleted, &xfrm->flow_cache_gc_count); fcp->hash_count -= deleted; spin_lock_bh(&xfrm->flow_cache_gc_lock); list_splice_tail(gc_list, &xfrm->flow_cache_gc_list); @@ -232,6 +236,13 @@ flow_cache_lookup(struct net *net, const struct flowi *key, u16 family, u8 dir, if (fcp->hash_count > fc->high_watermark) flow_cache_shrink(fc, fcp); + if (fcp->hash_count > 2 * fc->high_watermark || + atomic_read(&net->xfrm.flow_cache_gc_count) > fc->high_watermark) { + atomic_inc(&net->xfrm.flow_cache_genid); + flo = ERR_PTR(-ENOBUFS); + goto ret_object; + } + fle = kmem_cache_alloc(flow_cachep, GFP_ATOMIC); if (fle) { fle->net = net; @@ -446,6 +457,7 @@ int flow_cache_init(struct net *net) INIT_WORK(&net->xfrm.flow_cache_gc_work, flow_cache_gc_task); INIT_WORK(&net->xfrm.flow_cache_flush_work, flow_cache_flush_task); mutex_init(&net->xfrm.flow_flush_sem); + atomic_set(&net->xfrm.flow_cache_gc_count, 0); fc->hash_shift = 10; fc->low_watermark = 2 * flow_cache_hash_size(fc); -- cgit