Re: [Xen-ia64-devel] steal_page(MEMF_no_refcount) page->count_info no longer consistent

[Isaku Yamahata <yamahata@xxxxxxxxxxxxx>]

On Wed, Feb 28, 2007 at 04:55:27PM -0700, Alex Williamson wrote:

>    Current xen-unstable.hg tip has a problem booting dom0 that I'd like
> your opinion on.  We're failing the check in steal_page() that ensures
> that count_info is 2 when called with the MEMF_no_refcount flag.  In
> fact, it seems that steal_page() is now getting called for pages that
> have a count_info of 1 or 2.  Are we being overly paranoid with this
> check, or is this an indication of a deeper problem?  The change seems
> to have been introduced by the recent memory allocator changes which
> removed the bit width restrictions.  Thanks,

By the coarse code check, I couldn't find the case that count_info = 1
with MEMF_no_refcount can occur.
The reference count semantics seems to have been changed in a subtle way.
I'll try to reproduce it and take a deeper look into it.
-- 
yamahata

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