Messages in this thread | | | From | Johannes Weiner <> | Subject | Re: [v2.6.26] what's brewing in x86.git for v2.6.26 | Date | Thu, 17 Apr 2008 12:32:03 +0200 |
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Hi,
Andrew Morton <akpm@linux-foundation.org> 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
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