Messages in this thread | | | Subject | Re: [PATCH 00/10] foundations for reserve-based allocation | From | Peter Zijlstra <> | Date | Mon, 06 Aug 2007 21:36:58 +0200 |
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On Mon, 2007-08-06 at 12:31 -0700, Daniel Phillips wrote: > On Monday 06 August 2007 11:17, Peter Zijlstra wrote: > > And how do we know a page was taken out of the reserves? > > Why not return that in the low bit of the page address? This is a > little more cache efficient, does not leave that odd footprint in the > page union and forces the caller to examine the > alloc_pages(...P_MEMALLOC) return, making it harder to overlook the > fact that it got a page out of reserve and forget to put one back > later.
This would require auditing all page allocation sites to ensure they ever happen under PF_MEMALLOC or the like. Because if an allocator ever fails to check the low bit and assumes its a valid struct page *, stuff will go *bang*.
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