Re: r358252 causes intermittent hangs where processes are stuck sleeping on btalloc

From: Ryan Libby <rlibby_at_freebsd.org>
Date: Wed, 20 May 2020 23:58:50 -0700
On Wed, May 20, 2020 at 6:04 PM Rick Macklem <rmacklem_at_uoguelph.ca> wrote:
>
> Hi,
>
> Since I hadn't upgraded a kernel through the winter, it took me a while
> to bisect this, but r358252 seems to be the culprit.
>
> If I do a kernel build over NFS using my not so big Pentium 4 (single core,
> 1.25Gbytes RAM, i386), about every second attempt will hang.
> When I do a "ps" in the debugger, I see processes sleeping on btalloc.
> If I revert to r358251, I cannot reproduce this.
>
> Any ideas?
>
> I can easily test any change you might suggest to see if it fixes the
> problem.
>
> If you want more debug info, let me know, since I can easily
> reproduce it.
>
> Thanks, rick

Nothing obvious to me.  I can maybe try a repro on a VM...

ddb ps, acttrace, alltrace, show all vmem, show page would be welcome.

"btalloc" is "We're either out of address space or lost a fill race."
Received on Thu May 21 2020 - 04:59:04 UTC

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