kern/60004: zfs pgdaemon deadlock on range lock

["imuwoto%gmail.com@localhost via gnats" <gnats-admin%NetBSD.org@localhost>]

>Number:         60004
>Category:       kern
>Synopsis:       zfs pgdaemon deadlock on range lock
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Feb 14 18:00:01 +0000 2026
>Originator:     YAMAMOTO Takashi
>Release:        NetBSD 10.1
>Organization:
>Environment:
amd64
>Description:
pgdaemon:

db{0}> tr/a ffff811ebf487b80
trace: pid 0 lid 289 at 0xffffc51261102d40
sleepq_block() at netbsd:sleepq_block+0x13a
cv_wait() at netbsd:cv_wait+0xb7
zfs_range_lock() at zfs:zfs_range_lock+0x13d
zfs_netbsd_putpages() at zfs:zfs_netbsd_putpages+0xc1
VOP_PUTPAGES() at netbsd:VOP_PUTPAGES+0x43
uvm_pageout() at netbsd:uvm_pageout+0x20c
db{0}> 

some process:

db{0}> tr/a ffff811ecc0fc540
trace: pid 11847 lid 11847 at 0xffffc5126ec957a0
sleepq_block() at netbsd:sleepq_block+0x13a
mtsleep() at netbsd:mtsleep+0x146
uvmfault_promote() at netbsd:uvmfault_promote+0x235
uvm_fault_internal() at netbsd:uvm_fault_internal+0xce7
trap() at netbsd:trap+0x2f9
--- trap (number 6) ---
copyout() at netbsd:copyout+0x33
dmu_read_uio_dnode() at zfs:dmu_read_uio_dnode+0x83
dmu_read_uio_dbuf() at zfs:dmu_read_uio_dbuf+0x41
zfs_netbsd_read() at zfs:zfs_netbsd_read+0x37d
VOP_READ() at netbsd:VOP_READ+0x42
vn_read() at netbsd:vn_read+0x18e
dofileread() at netbsd:dofileread+0x79
sys_read() at netbsd:sys_read+0x49
syscall() at netbsd:syscall+0x1fc
--- syscall (number 3) ---
netbsd:syscall+0x1fc:
db{0}>

https://gnats.netbsd.org/cgi-bin/query-pr-single.pl?number=58964
has a similar symptom. but it looks like a different deadlock.

>How-To-Repeat:

>Fix: