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Date: Wed, 22 Jul 2015 12:55:28 +0200 From: Frank Schreuder <fschreuder@...nsip.nl> To: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>, Florian Westphal <fw@...len.de> CC: Johan Schuijt <johan@...nsip.nl>, Eric Dumazet <eric.dumazet@...il.com>, "nikolay@...hat.com" <nikolay@...hat.com>, "davem@...emloft.net" <davem@...emloft.net>, "chutzpah@...too.org" <chutzpah@...too.org>, Robin Geuze <robing@...nsip.nl>, netdev <netdev@...r.kernel.org> Subject: Re: reproducable panic eviction work queue Hi Nikolay, Thanks for this patch. I'm no longer able to reproduce this panic on our test environment! The server has been handling >120k fragmented UDP packets per second for over 40 minutes So far everything is running stable without stacktraces in the logs. All other panics happened within 5-10 minutes. I will let this test environment run for another day or 2. I will inform you as soon as something happens! Thanks, Frank Op 7/22/2015 om 11:11 AM schreef Nikolay Aleksandrov: > On 07/22/2015 10:17 AM, Frank Schreuder wrote: >> I got some additional information from syslog: >> >> Jul 22 09:49:33 dommy0 kernel: [ 675.987890] NMI watchdog: BUG: soft lockup - CPU#3 stuck for 22s! [kworker/3:1:42] >> Jul 22 09:49:42 dommy0 kernel: [ 685.114033] INFO: rcu_sched self-detected stall on CPU { 3} (t=39918 jiffies g=988 c=987 q=23168) >> >> Thanks, >> Frank >> >> > Hi, > It looks like it's happening because of the evict_again logic, I think we should also > add Florian's first suggestion about simplifying it to the patch and just skip the > entry if we can't delete its timer otherwise we can restart the eviction and see > entries that already had their timer stopped by us and can keep restarting for > a long time. > Here's an updated patch that removes the evict_again logic. > > > diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h > index e1300b3dd597..56a3a5685f76 100644 > --- a/include/net/inet_frag.h > +++ b/include/net/inet_frag.h > @@ -45,6 +45,7 @@ enum { > * @flags: fragment queue flags > * @max_size: maximum received fragment size > * @net: namespace that this frag belongs to > + * @list_evictor: list of queues to forcefully evict (e.g. due to low memory) > */ > struct inet_frag_queue { > spinlock_t lock; > @@ -59,6 +60,7 @@ struct inet_frag_queue { > __u8 flags; > u16 max_size; > struct netns_frags *net; > + struct hlist_node list_evictor; > }; > > #define INETFRAGS_HASHSZ 1024 > diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c > index 5e346a082e5f..aaae37949c14 100644 > --- a/net/ipv4/inet_fragment.c > +++ b/net/ipv4/inet_fragment.c > @@ -138,27 +138,17 @@ evict_again: > if (!inet_fragq_should_evict(fq)) > continue; > > - if (!del_timer(&fq->timer)) { > - /* q expiring right now thus increment its refcount so > - * it won't be freed under us and wait until the timer > - * has finished executing then destroy it > - */ > - atomic_inc(&fq->refcnt); > - spin_unlock(&hb->chain_lock); > - del_timer_sync(&fq->timer); > - inet_frag_put(fq, f); > - goto evict_again; > - } > + if (!del_timer(&fq->timer)) > + continue; > > fq->flags |= INET_FRAG_EVICTED; > - hlist_del(&fq->list); > - hlist_add_head(&fq->list, &expired); > + hlist_add_head(&fq->list_evictor, &expired); > ++evicted; > } > > spin_unlock(&hb->chain_lock); > > - hlist_for_each_entry_safe(fq, n, &expired, list) > + hlist_for_each_entry_safe(fq, n, &expired, list_evictor) > f->frag_expire((unsigned long) fq); > > return evicted; > @@ -284,8 +274,7 @@ static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f) > struct inet_frag_bucket *hb; > > hb = get_frag_bucket_locked(fq, f); > - if (!(fq->flags & INET_FRAG_EVICTED)) > - hlist_del(&fq->list); > + hlist_del(&fq->list); > spin_unlock(&hb->chain_lock); > } > > > -- TransIP BV Schipholweg 11E 2316XB Leiden E: fschreuder@...nsip.nl I: https://www.transip.nl -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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