From e588e2f286ed7da011ed357c24c5b9a554e26595 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Thu, 6 Mar 2014 18:06:41 +0100 Subject: [PATCH] inet: frag: make sure forced eviction removes all frags Quoting Alexander Aring: While fragmentation and unloading of 6lowpan module I got this kernel Oops after few seconds: BUG: unable to handle kernel paging request at f88bbc30 [..] Modules linked in: ipv6 [last unloaded: 6lowpan] Call Trace: [] ? call_timer_fn+0x54/0xb3 [] ? process_timeout+0xa/0xa [] run_timer_softirq+0x140/0x15f Problem is that incomplete frags are still around after unload; when their frag expire timer fires, we get crash. When a netns is removed (also done when unloading module), inet_frag calls the evictor with 'force' argument to purge remaining frags. The evictor loop terminates when accounted memory ('work') drops to 0 or the lru-list becomes empty. However, the mem accounting is done via percpu counters and may not be accurate, i.e. loop may terminate prematurely. Alter evictor to only stop once the lru list is empty when force is requested. Reported-by: Phoebe Buckheister Reported-by: Alexander Aring Tested-by: Alexander Aring Signed-off-by: Florian Westphal Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/inet_fragment.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c index 322dcebfc588..3b01959bf4bb 100644 --- a/net/ipv4/inet_fragment.c +++ b/net/ipv4/inet_fragment.c @@ -208,7 +208,7 @@ int inet_frag_evictor(struct netns_frags *nf, struct inet_frags *f, bool force) } work = frag_mem_limit(nf) - nf->low_thresh; - while (work > 0) { + while (work > 0 || force) { spin_lock(&nf->lru_lock); if (list_empty(&nf->lru_list)) { -- 2.20.1