Re: CVS commit: src/sys/uvm

[Mindaugas Rasiukevicius <rmind%netbsd.org@localhost>]

Matt Thomas <matt%3am-software.com@localhost> wrote:
> 
> On Sep 3, 2012, at 3:33 PM, Mindaugas Rasiukevicius wrote:
> 
> > "Matt Thomas" <matt%netbsd.org@localhost> wrote:
> >> Module Name:       src
> >> Committed By:      matt
> >> Date:              Mon Sep  3 19:53:43 UTC 2012
> >> 
> >> Modified Files:
> >>    src/sys/uvm: uvm_km.c uvm_map.c
> >> 
> >> Log Message:
> >> Switch to a spin lock (uvm_kentry_lock) which, fortunately, was sitting
> >> there unused.
> > 
> > - pmap_growkernel() may use adaptive locks, which cannot be acquired
> > with the spin lock held; so the change breaks at least x86 and alpha.
> > 
> > - Why in the caller?  I think it would be better do leave it for the
> > pmaps, e.g. they may re-use the locks which already provide the
> > necessary protection and which need to be taken anyway (like in x86
> > pmap).
> 
> uvm_maxkaddr need a lock for its updating
> 
> growkernel can be called uvm_km_mem_alloc which might be called
> at interrupt level.

The second point stands, but I see you already fixed it - thanks!

As for pmap_growkernel() being called from interrupt context - right, then
it seems Xen is broken, as its path in pmap_growkernel() acquires adaptive
pmaps_lock and might call pool_cache_invalidate() which can block..

-- 
Mindaugas