Re: BIO Usage Error or Conflicting Designs

Manfred Spraul (manfred@colorfullife.com)
Sun, 13 Jan 2002 22:09:06 +0100



Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

>
> Is this with the highmem debug stuff enabled? That's the only way I can
> see this BUG triggering, otherwise q->bounce_pfn _cannot_ be smaller
> than the max_pfn.
>
Have you tested that?

Unless I misread arch/i386/kernel/setup.c, line 740 to 760, max_pfn is
the upper end of the highmem area, if highmem is configured.
For non-highmem setup, it's set to min(system_memory, 4 GB).
It was a local variable within setup_arch, and someone made it a global
variable.

I.e. max_pfn is 1 GB with Andre's setup.

His patch doesn't touch the bounce limit, the default limit from
blk_queue_make_request() is used: BLK_BOUNCE_HIGH, which is max_low_pfn.

max_low_pfn is 896 MB.

--> BUG in create_bounce(), because a request comes in with a bounce
limit less than the total system memory, and no highmem configured.

--
	Manfred
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/