Re: port-evbarm/56944: ZFS heavy usage on NetBSD running in Mac M1 VM results in kernel thread running away and filesystem hang

[Chuck Silvers <chuq%chuq.com@localhost>]

The following reply was made to PR port-evbarm/56944; it has been noted by GNATS.

From: Chuck Silvers <chuq%chuq.com@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: port-evbarm/56944: ZFS heavy usage on NetBSD running in Mac M1
 VM results in kernel thread running away and filesystem hang
Date: Sat, 30 Jul 2022 05:20:10 -0700

 On Sat, Jul 30, 2022 at 07:19:41AM -0400, Brad Spencer wrote:
 
 (from your ddb output file)
 
 # pgdaemon
 db{0}> trace/a ffff8f305b4e7780
 trace: pid 0 lid 112 at 0xffffad007259bb00
 sleepq_block() at netbsd:sleepq_block+0x13a
 cv_wait() at netbsd:cv_wait+0x49
 txg_wait_open() at zfs:txg_wait_open+0x6c
 dmu_tx_assign() at zfs:dmu_tx_assign+0x2c4
 zvol_strategy() at zfs:zvol_strategy+0x1a9
 spec_strategy() at netbsd:spec_strategy+0x6e
 VOP_STRATEGY() at netbsd:VOP_STRATEGY+0x3c
 bdev_strategy() at netbsd:bdev_strategy+0xc8
 spec_strategy() at netbsd:spec_strategy+0x6e
 VOP_STRATEGY() at netbsd:VOP_STRATEGY+0x3c
 uvm_swap_io() at netbsd:uvm_swap_io+0x21f
 swapcluster_flush.part.0() at netbsd:swapcluster_flush.part.0+0x85
 uvm_pageout() at netbsd:uvm_pageout+0x478
 
 
 oh, you've got a zvol as swap space.  that has never worked on netbsd
 and it's not going to work for the foreseeable future.  using a zfs file
 as a swap file will also hang eventually.  you'll need to change your setup
 to have the swap space be something that doesn't involve zfs.
 
 -Chuck