Re: [PATCH] mmc-atmel : fix kunmap wrong usage

From: Nicolas Ferre
Date: Fri Jun 22 2007 - 09:34:58 EST


Hugh Dickins :
Aren't you just guessing there? Those kunmap_atomics in at91_mci.c
may look wrong to you, but they're not incorrect (so long as sg->offset
falls within the page, as it must do here to make sense of the page).
Especially not on ARM, where kunmap_atomic actually has no interest
in the argument passed. And the oops was in the flush_dcache_page.

If you actually reproduced Nicolas' problem on ARM, and verified
that your patch then fixes it, please let us know: that will be
remarkably interesting.

Patch tested without success. Indeed, I always see the Oops with Marc's patch.

I believe I posted the correct fix last night (or at least a safe fix
for now: Christoph Lameter may prefer to undo it and change ARM's
dma_mapping at leisure later), checking PageSlab in page_mapping;
and Linus has already put that one into his git tree.

Here:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=b9bae3402572dc50a1e084c5b1ae5117918ef0f0

But it would be good to hear from Nicolas whether that indeed fixes
his oops: I couldn't actually try my patch on ARM either.

Ok tested on Atmel ARM AT91 (at91sam9263), this fixes this oops.

Thanks a lot to all of you for your precise help.

Regards,
--
Nicolas Ferre


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