Re: kern/50375: layerfs (nullfs) locking problem leading to livelock

["J. Hannken-Illjes" <hannken%eis.cs.tu-bs.de@localhost>]

The following reply was made to PR kern/50375; it has been noted by GNATS.

From: "J. Hannken-Illjes" <hannken%eis.cs.tu-bs.de@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: Jeff Rizzo <riz%NetBSD.org@localhost>
Subject: Re: kern/50375: layerfs (nullfs) locking problem leading to livelock
Date: Tue, 10 Nov 2015 11:18:56 +0100

 This deadlock looks like vmem exhaustion:
 
 1) Threads 19955, 26028, 25222 and 17766 wait for the vnode
    lock 0x92ffc4d4.
 
    This lock is held by thread 0x96ddc9e0 waiting in vmem_xalloc
    for vmem to become available.
 
 2) Thread 4849 waits for vnode lock 0x926cbb04.
 
    This lock is held by thread 0x96ddd4e0 also waiting
    in vmem_xalloc for vmem to become available.
 
 Has nothing to do with layerfs, no "VOP_LOCK > layer_lock > VOP_LOCK"
 sequences in the backtrace of the blocked threads.
 
 Could we conclude the patch fixes your issue with layerfs deadlock?
 
 --
 J. Hannken-Illjes - hannken%eis.cs.tu-bs.de@localhost - TU Braunschweig (Germany)