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SubjectRe: __get_free_pages(): is the MEM really mine?
Greetings from the 2001 Linux Devel meeting in Oldenburg!

Roman Zippel looked at my driver and added code to print the usage
counter for each page after a 9-order __get_free_pages().

We found that only the first (!) page has a count of 1, the others have 0!

That would cover my impression, that only the 1st page is really mine...

Roman found that strange and added this:

struct page * page = virt_to_page(card_ptr->dma_blk1[n]);
int i;
for(i = 0; i < (1 << max_order); i++, page++)
{
atomic_set(&page->count, 1);
}

And the freeing of the pages is now done page by page in the _vma_close()
function.

I will now test the version but I have only a 1-CPU box here. On an SMP Box I
could imagine that even between __get_free_pages() and the
atomic_set(&page->count, 1) someone else already uses my pages.

Could you please comment on this?

Thanks,
--
Bernd Harries

bha@gmx.de http://www.freeyellow.com/members/bharries
bha@nikocity.de Tel. +49 421 809 7343 priv. | MSB First!
harries@stn-atlas.de +49 421 457 3966 offi. | Linux-m68k
bernd@linux-m68k.org 8.48'21" E 52.48'52" N | Medusa T40
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