Re: kern/58666: panic: lock error: Reader / writer lock: rw_vector_enter,357: locking against myself

[" Taylor R Campbell via gnats" <gnats-admin%NetBSD.org@localhost>]

The following reply was made to PR kern/58666; it has been noted by GNATS.

From: Taylor R Campbell <riastradh%NetBSD.org@localhost>
To: Havard Eidnes <he%NetBSD.org@localhost>
Cc: gnats-bugs%NetBSD.org@localhost,
	netbsd-bugs%NetBSD.org@localhost, Chuck Silvers <chs%NetBSD.org@localhost>
Subject: Re: kern/58666: panic: lock error: Reader / writer lock:
	rw_vector_enter,357: locking against myself
Date: Sun, 8 Sep 2024 17:12:18 +0000

 > Date: Sun, 8 Sep 2024 12:04:36 +0000
 > From: Taylor R Campbell <riastradh%NetBSD.org@localhost>
 > 
 > 5. RAM is currently short so uvm_km_alloc would have to sleep and wait
 >    for the pagedaemon to free pages before it can return, in which
 >    case it returns null instead of sleeping because pmap_pdp_alloc
 >    didn't pass UVM_KMF_WAITVA.
 
 Correction: kernel virtual address space, not RAM, is short, so
 uvm_km_alloc would have to sleep and wait for the pagedaemon to find
 some kva pages to free.  By passing UVM_KMF_WAITVA, pmap_pdp_alloc
 would wait for kva instead of returning null.