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Message-ID: <20141027155938.28248b5e@gentoo.org> Date: Mon, 27 Oct 2014 15:59:38 -0700 From: Patrick McLean <chutzpah@...too.org> To: Nikolay Aleksandrov <nikolay@...hat.com> Cc: Eric Dumazet <eric.dumazet@...il.com>, Florian Westphal <fw@...len.de>, Stephen Hemminger <stephen@...workplumber.org>, netdev@...r.kernel.org Subject: Re: [Bug 86851] New: Reproducible panic on heavy UDP traffic On Mon, 27 Oct 2014 09:48:15 +0100 Nikolay Aleksandrov <nikolay@...hat.com> wrote: > On 10/27/2014 01:47 AM, Eric Dumazet wrote: > > On Mon, 2014-10-27 at 00:28 +0100, Nikolay Aleksandrov wrote: > > > >> > >> Thanks for CCing me. > >> I'll dig in the code tomorrow but my first thought when I saw this > >> was could it be possible that we have a race condition between > >> ip_frag_queue() and inet_frag_evict(), more precisely between the > >> ipq_kill() calls from ip_frag_queue and inet_frag_evict since the > >> frag could be found before we have entered the evictor which then > >> can add it to its expire list but the ipq_kill() from > >> ip_frag_queue() can do a list_del after we release the chain lock > >> in the evictor so we may end up like this ? > > > > Yes, either we use hlist_del_init() but loose poison aid, or test if > > frag was evicted : > > > > Not sure about refcount. > > > > diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c > > index 9eb89f3f0ee4..894ec30c5896 100644 > > --- a/net/ipv4/inet_fragment.c > > +++ b/net/ipv4/inet_fragment.c > > @@ -285,7 +285,8 @@ 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); > > - hlist_del(&fq->list); > > + if (!(fq->flags & INET_FRAG_EVICTED)) > > + hlist_del(&fq->list); > > spin_unlock(&hb->chain_lock); > > } > > > > > > > > Exactly, I was thinking about a similar fix since the evict flag is > only set with the chain lock. IMO the refcount should be fine. > CCing the reporter. > Patrick could you please try Eric's patch ? > It no longer panics with that patch, but it does produce a large amount of warnings, here is an example of what I am getting. I will attach the full log to the bug. > [ 205.042923] ------------[ cut here ]------------ > [ 205.042933] WARNING: CPU: 4 PID: 615 at net/ipv4/inet_fragment.c:149 inet_evict_bucket+0x172/0x180() > [ 205.042934] Modules linked in: nfs fscache nfsd auth_rpcgss nfs_acl lockd grace sunrpc 8021q garp mrp bonding x86_pkg_temp_thermal joydev sb_edac edac_core ioatdma tpm_tis ext4 mbcache jbd2 igb ixgbe i2c_algo_bit raid1 mdio crc32c_intel megaraid_sas dca > [ 205.042953] CPU: 4 PID: 615 Comm: kworker/4:2 Not tainted 3.18.0-rc2-base-7+ #3 > [ 205.042955] Hardware name: Intel Corporation S2600GZ/S2600GZ, BIOS SE5C600.86B.02.03.0003.041920141333 04/19/2014 > [ 205.042957] Workqueue: events inet_frag_worker > [ 205.042958] 0000000000000000 0000000000000009 ffffffff81624cd2 0000000000000000 > [ 205.042960] ffffffff81117b7d ffff8817c83a4740 0000000000000000 ffffffff81aa6820 > [ 205.042962] ffff8817ce073d70 ffff8817c83a4738 ffffffff81597cb2 ffffffff81aa8e28 > [ 205.042964] Call Trace: > [ 205.042969] [<ffffffff81624cd2>] ? dump_stack+0x41/0x51 > [ 205.042973] [<ffffffff81117b7d>] ? warn_slowpath_common+0x6d/0x90 > [ 205.042975] [<ffffffff81597cb2>] ? inet_evict_bucket+0x172/0x180 > [ 205.042976] [<ffffffff81597d22>] ? inet_frag_worker+0x62/0x210 > [ 205.042979] [<ffffffff8112c312>] ? process_one_work+0x132/0x360 > [ 205.042981] [<ffffffff8112ca23>] ? worker_thread+0x113/0x590 > [ 205.042983] [<ffffffff8112c910>] ? rescuer_thread+0x3d0/0x3d0 > [ 205.042986] [<ffffffff8113123c>] ? kthread+0xbc/0xe0 > [ 205.042991] [<ffffffff81040000>] ? xen_teardown_timer+0x10/0x70 > [ 205.042993] [<ffffffff81131180>] ? kthread_create_on_node+0x170/0x170 > [ 205.042996] [<ffffffff8162a9fc>] ? ret_from_fork+0x7c/0xb0 > [ 205.042998] [<ffffffff81131180>] ? kthread_create_on_node+0x170/0x170 > [ 205.043000] ---[ end trace ed2bb7d412e082bc ]--- > [ 205.752744] ------------[ cut here ]------------ > [ 205.752752] WARNING: CPU: 2 PID: 610 at net/ipv4/inet_fragment.c:149 inet_evict_bucket+0x172/0x180() > [ 205.752754] Modules linked in: nfs fscache nfsd auth_rpcgss nfs_acl lockd grace sunrpc 8021q garp mrp bonding x86_pkg_temp_thermal joydev sb_edac edac_core ioatdma tpm_tis ext4 mbcache jbd2 igb ixgbe i2c_algo_bit raid1 mdio crc32c_intel megaraid_sas dca > [ 205.752773] CPU: 2 PID: 610 Comm: kworker/2:2 Tainted: G W 3.18.0-rc2-base-7+ #3 > [ 205.752774] Hardware name: Intel Corporation S2600GZ/S2600GZ, BIOS SE5C600.86B.02.03.0003.041920141333 04/19/2014 > [ 205.752777] Workqueue: events inet_frag_worker > [ 205.752779] 0000000000000000 0000000000000009 ffffffff81624cd2 0000000000000000 > [ 205.752780] ffffffff81117b7d ffff882fc473c740 0000000000000000 ffffffff81aa6820 > [ 205.752782] ffff8817ce7afd70 ffff882fc473c738 ffffffff81597cb2 ffffffff81aa87a8 > [ 205.752784] Call Trace: > [ 205.752790] [<ffffffff81624cd2>] ? dump_stack+0x41/0x51 > [ 205.752793] [<ffffffff81117b7d>] ? warn_slowpath_common+0x6d/0x90 > [ 205.752795] [<ffffffff81597cb2>] ? inet_evict_bucket+0x172/0x180 > [ 205.752797] [<ffffffff81597d22>] ? inet_frag_worker+0x62/0x210 > [ 205.752799] [<ffffffff8112c312>] ? process_one_work+0x132/0x360 > [ 205.752801] [<ffffffff8112ca23>] ? worker_thread+0x113/0x590 > [ 205.752803] [<ffffffff8112c910>] ? rescuer_thread+0x3d0/0x3d0 > [ 205.752806] [<ffffffff8113123c>] ? kthread+0xbc/0xe0 > [ 205.752810] [<ffffffff81040000>] ? xen_teardown_timer+0x10/0x70 > [ 205.752812] [<ffffffff81131180>] ? kthread_create_on_node+0x170/0x170 > [ 205.752815] [<ffffffff8162a9fc>] ? ret_from_fork+0x7c/0xb0 > [ 205.752818] [<ffffffff81131180>] ? kthread_create_on_node+0x170/0x170 > [ 205.752820] ---[ end trace ed2bb7d412e082bd ]--- > [ 206.737865] ------------[ cut here ]------------ -- 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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