PR/60584 CVS commit: src/sys/kern

["Izumi Tsutsui" <tsutsui%netbsd.org@localhost>]

The following reply was made to PR kern/60584; it has been noted by GNATS.

From: "Izumi Tsutsui" <tsutsui%netbsd.org@localhost>
To: gnats-bugs%gnats.NetBSD.org@localhost
Cc: 
Subject: PR/60584 CVS commit: src/sys/kern
Date: Mon, 21 Sep 2026 04:24:36 +0000

 Module Name:	src
 Committed By:	tsutsui
 Date:		Mon Sep 21 04:24:36 UTC 2026
 
 Modified Files:
 	src/sys/kern: vfs_bio.c
 
 Log Message:
 vfs_bio: retry fresh buffer allocation if recycling fails
 
 getnewbuf() uses buf_lotsfree() to choose whether to
 allocate a fresh buffer before trying BQ_AGE and BQ_LRU.
 
 If fresh allocation is skipped and no buffer can actually be
 recycled, it sleeps on needbuffer_cv even when the buffer cache
 is still below its high water mark.
 
 In that situation, a thread which could release a buffer may
 itself need another buffer, resulting in a deadlock.
 
 To avoid this, if recycling finds no usable buffer and bufmem is
 still below bufmem_hiwater, make one more PR_NOWAIT fresh allocation
 attempt before sleeping.  See PR kern/60584 for details.
 
 Worth to pullup to netbsd-11.
 
 
 To generate a diff of this commit:
 cvs rdiff -u -r1.308 -r1.309 src/sys/kern/vfs_bio.c
 
 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.