> On Jul 13, 2015, at 11:29 AM, Dan McDonald <dan...@omniti.com> wrote:
>
>
>> On Jul 13, 2015, at 11:25 AM, Derek Yarnell <de...@umiacs.umd.edu> wrote:
>>
>> https://obj.umiacs.umd.edu/derek_support/vmdump.0
>
> Yeah, that's what I'm seeking. Downloading it now to an r151014 box (you are
> running r151014 according to the first mail). My normal '014 box is
> otherwise indisposed at the moment, so this dump may take a bit longer to
> analyze. I can forward it along to the ZFS folks once I've done my initial
> analysis.
>
> For bugs like these, I usually have to engage the illumos ZFS list. If
> anyone here wants to follow along, I'll Cc: you on anything I report to them.
Okay, it's a VERIFY() failure in zio_buf_alloc(). It's passed a size of 0 by
its caller. Observe this MDB interaction:
> $c
vpanic()
0xfffffffffba8b13d()
zio_buf_alloc+0x49(0)
arc_get_data_buf+0x12b(ffffff0d4071ca98)
arc_buf_alloc+0xd2(ffffff0d4dfec000, 0, 0, 1)
...<SNIP!>
0xffffff0d4071ca98 is an arc_buf_t, read off of disk. The code in
arc_get_data_buf starts with:
static void
arc_get_data_buf(arc_buf_t *buf)
{
arc_state_t *state = buf->b_hdr->b_l1hdr.b_state;
uint64_t size = buf->b_hdr->b_size;
arc_buf_contents_t type = arc_buf_type(buf->b_hdr);
So let's look at that size:
> ffffff0d4071ca98::print arc_buf_t b_hdr |::print arc_buf_hdr_t b_size
b_size = 0
>
Ouch. There's your zero.
I'm going to forward this very note to the illumos ZFS list. I see ONE
possible bugfix post-r151014 that might help:
commit 31c46cf23cd1cf4d66390a983dc5072d7d299ba2
Author: Alek Pinchuk <a...@nexenta.com>
Date: Tue Jun 30 09:44:11 2015 -0700
6033 arc_adjust() should search MFU lists for oldest buffer when adjusting
MFU size
Reviewed by: Saso Kiselkov <saso.kisel...@nexenta.com>
Reviewed by: Xin Li <delp...@delphij.net>
Reviewed by: Prakash Surya <m...@prakashsurya.com>
Approved by: Matthew Ahrens <mahr...@delphix.com>
It's a small bug, and I shudder to say this, even hot-patchable on a running
system if you're desperate. :)
Thanks,
Dan
d
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