Re: [v2.6.26] what's brewing in x86.git for v2.6.26

[Johannes Weiner]

Hi,

Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> writes:

> - extensive damage to the page-flags patches
>
>   Did you check that all architectures and configurations still have
>   sufficient page flags for us to be able to consume another one for
>   kmemcheck?  The MM developers have put much, much effort into avoiding
>   running out of flags over numerous years and afaik none of them even know
>   that this debug feature is using one of the few remaining ones.
>
>   What do we do when we run out?

Would it be feasible to add another unsigned long to struct page?  I
mean, extending such a common structure always sucks, but for
emergency...

#define PageFoobar(page)	test_bit(PG_foobar, &(page)->flags2)

Of course the essential core flags should always be in ->flags but
perhaps we could have a symbol CONFIG_NEED_EXTRA_PAGE_FLAGS that gets
selected by kmemcheck (and other candidates that are unlikely to be
enabled most of the time) and then #ifndef ->flags2 out.

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