The following reply was made to PR kern/55402; it has been noted by GNATS.
From: =?UTF-8?B?SmFyb23DrXIgRG9sZcSNZWs=?= <jaromir.dolecek%gmail.com@localhost>
To: "gnats-bugs%NetBSD.org@localhost" <gnats-bugs%netbsd.org@localhost>
Cc:
Subject: Re: kern/55402: amd64/9.99.68/9.99.68: xen/zfs - kernel: double fault
trap, code=0
Date: Sat, 20 Jun 2020 18:55:28 +0200
Le sam. 20 juin 2020 =C3=A0 15:45, Frank Kardel <kardel%netbsd.org@localhost> a =C3=
=A9crit :
> Well it goes a bit further but hits the double fault
>
> now with 57 frames (two > 1k) at about the same accumulated stack size.
>
> Some space was saved by the patch, but presumably not enough.
OK, I've updated the patch. My previous change in
vdev_queue_io_to_issue() did not work, gcc returns the stack on the
end of the function, not when going out of the block.
New version reduced vdev_queue_io_to_issue() to use only 160 bytes of
stack instead of 1152, and dsl_scan_visitbp()+ dsl_scan_visitdnode()
pair now takes 40 less bytes.
Can you check if this is enough to get it through?
http://www.netbsd.org/~jdolecek/zfs_reduce_stack.diff
Jaromir