re: kern/16789

[matthew green <mrg%eterna.com.au@localhost>]

The following reply was made to PR kern/16789; it has been noted by GNATS.

From: matthew green <mrg%eterna.com.au@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
    netbsd-bugs%netbsd.org@localhost, mkiiskila%yahoo.com@localhost
Subject: re: kern/16789
Date: Thu, 25 Oct 2018 09:24:10 +1100

 >  >  dump to unopened disk fails (e.g. dump do wd1b when wd1a not mounted=
 ), due
 >  >  to the open path executing ata_get_params(), which eventually tsleep=
 s()
 >  >  while waiting for the command to finish; specifically, if WDF_LOADED=
  is not
 >  >  set
 >  >  - happens due to wd_get_params() with just AT_WAIT in wdopen()
 >  >  - not easy to fix, open needs to read disklabel and all this mechani=
 cs
 >  >    is too much for emergency crash dump code path
 >  =
 
 >  Would it be reasonable to open wd1b when it is configured as dump
 >  device? I assume if it is also a swap device, it works fine?
 
 this seems like the best way to solve this sanely, though i suspect
 it will require some hacks to avoid double-open when also swap device,
 but since uvm_swap.c handles these, it should be fairly local hack,
 though it will need to handle both dump or swap having the partition
 open first, since the admin can set either in any order.
 
 
 .mrg.