Messages in this thread | | | Date | Thu, 4 Mar 2010 21:44:35 +0000 | From | Russell King - ARM Linux <> | Subject | Re: [RFC PATCH] ARM: Assume new page cache pages have dirty D-cache |
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On Thu, Mar 04, 2010 at 06:36:42PM +0000, Catalin Marinas wrote: > ARM: Assume new page cache pages have dirty D-cache > > From: Catalin Marinas <catalin.marinas@arm.com> > > There are places in Linux where writes to newly allocated page cache > pages happen without a subsequent call to flush_dcache_page() (several > PIO drivers including USB HCD). This patch changes the meaning of > PG_arch_1 to be PG_dcache_clean and always flush the D-cache for a newly > mapped page in update_mmu_cache(). > > The patch also sets the PG_arch_1 bit in the DMA cache maintenance > function to avoid additional cache flushing in update_mmu_cache().
As I just realised, this is going to subject all pages placed into userspace with a D cache flush - even anonymous pages, and those which we've been careful to deal with the cache issues already (eg, via the COW page copying code.)
I think all the copypage functions need to set PG_dcache_clean on the new pages once their copy has completed.
I wonder if there's any other anonymous page creating functions which could do with a similar treatment...
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