Re: kern/55402: amd64/9.99.68/9.99.68: xen/zfs - kernel: double fault trap, code=0

[Jaromír Doleček <jaromir.dolecek%gmail.com@localhost>]

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 20:39:52 +0200

 Can you confirm whether it's enough to apply just the change for
 vdev_queue.c, i.e. can you try the scrum with dsl_scan.c same as in
 repository (without patch)?
 
 I'd prefer to keep dsl_scan.c closer to upstream unless absolutely
 necessary to change.
 
 Jaromir
 
 Le sam. 20 juin 2020 =C3=A0 20:28, Frank Kardel <kardel%netbsd.org@localhost> a =C3=
 =A9crit :
 >
 > That did it - the scrub run now completed successfully.
 >
 > Frank
 >
 >
 > On 06/20/20 19:00, Jarom=C3=ADr Dole=C4=8Dek wrote:
 > > The following reply was made to PR kern/55402; it has been noted by GNA=
 TS.
 > >
 > > From: =3D?UTF-8?B?SmFyb23DrXIgRG9sZcSNZWs=3D?=3D <jaromir.dolecek@gmail=
 .com>
 > > 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: doubl=
 e fault
 > >   trap, code=3D0
 > > Date: Sat, 20 Jun 2020 18:55:28 +0200
 > >
 > >   Le sam. 20 juin 2020 =3DC3=3DA0 15:45, Frank Kardel <kardel%netbsd.or@localhost=
 g> a =3DC3=3D
 > >   =3DA9crit :
 > >   >  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
 > >
 >