Re: [patch 1/3] mmu_notifier: Core code

From: Christoph Lameter
Date: Mon Feb 04 2008 - 14:14:11 EST


On Sun, 3 Feb 2008, Andrea Arcangeli wrote:

> On Thu, Jan 31, 2008 at 07:58:40PM -0800, Christoph Lameter wrote:
> > Ok. Andrea wanted the same because then he can void the begin callouts.
>
> Exactly. I hope the page-pin will avoid me having to serialize the KVM
> page fault against the start/end critical section.
>
> BTW, I wonder if the start/end critical section API is intended to
> forbid scheduling inside it. In short I wonder if GRU can is allowed
> to take a spinlock in _range_start as last thing before returning, and
> to release that same spinlock in _range_end as first thing, and not to
> be forced to use a mutex.

_begin/end encloses code that may sleep and _begin/_end itself may sleep.
So a semaphore may work but not a spinlock.

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