Re: 2.6.28-rc9 panics with crashkernel=256M while booting

From: Chandru
Date: Thu Jan 22 2009 - 03:20:41 EST

On Thursday 22 January 2009 05:59:39 Dave Hansen wrote:
> Let's take, for instance, a 1-byte reservation. With this code, you've
> suddenly turned that into a 0-byte reservation, and that *can't* be
> right. The same thing happens if you have a reservation that spans two
> pages. If you unconditionally round it down, then you might miss the
> part that spans a portion of the second page.
> It needs to be rounded down like you are suggesting here, but only in
> the case where we've gone over the *CURRENT* node's boundary. This is
> kinda what that "if (end_pfn > node_ar.end_pfn)" check is doing. But,
> it evidently screws it up if the overlap isn't by an entire page or
> something.

I assumed the condition 'while (start_pfn < end_pfn && .. )' asks for atleast
a PAGE_SIZE difference between them and hence went ahead with that patch.
My guess was a 1-byte , 2-byte or a (PAGE_SIZE -1)-byte reservations may not even
go into that loop. However we just need a fix for this problem. So if there is a
better fix that you have please post it to lkml.

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