Re: massive memory leak in 3.1[3-5] with nfs4+kerberos

[Carlos Carvalho <carlos@fisica.ufpr.br>]

J. Bruce Fields (bfields@fieldses.org) wrote on Tue, Oct 14, 2014 at 05:42:45PM BRT:
> On Mon, Oct 13, 2014 at 08:50:27PM -0300, Carlos Carvalho wrote:
> > J. Bruce Fields (bfields@fieldses.org) wrote on Mon, Oct 13, 2014 at 10:58:40AM BRT:
> > Note the big xprt_alloc. slabinfo is found in the kernel tree at tools/vm.
> > Another way to see it:
> > 
> > urquell# sort -n /sys/kernel/slab/kmalloc-2048/alloc_calls | tail -n 2
> >    1519 nfsd4_create_session+0x24a/0x810 age=189221/25894524/71426273 pid=5372-5436 cpus=0-11,13-16,19-20 nodes=0-1
> > 3380755 xprt_alloc+0x1e/0x190 age=5/27767270/71441075 pid=6-32599 cpus=0-31 nodes=0-1
> 
> Agreed that the xprt_alloc is suspicious, though I don't really
> understand these statistics.
> 
> Since you have 4.1 clients, maybe this would be explained by a leak in
> the backchannel code.

We've set clients to use 4.0 and it only made the problem worse; the growth in
unreclaimable memory was faster.

> It could certainly still be worth testing 3.17 if possible.

We tested it and it SEEMS the problem doesn't appear in 3.17.1; the SUnreclaim
value oscillates up and down as usual, instead of increasing monotonically.
However it didn't last long enough for us to get conclusive numbers because
after about 5-6h the machine fills the screen with "NMI watchdog CPU #... is
locked for more than 22s". It spits these messages for many cores at once, and
becomes unresponsive; we have to reboot it from the console with alt+sysreq.

Do these 2 new pieces of info give a clue?