Messages in this thread | | | Date | Fri, 08 Aug 2014 19:09:30 +0530 | From | Chintan Pandya <> | Subject | Re: [PATCH] export the function kmap_flush_unused. |
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On 08/08/2014 02:46 PM, Sha, Ruibin wrote: > export the function kmap_flush_unused. > > Scenario: When graphic driver need high memory spece, we use alloc_pages() > to allocate. But if the allocated page has just been > mapped in the KMAP space(like first kmap then kunmap) and > no flush page happened on PKMAP, the page virtual address is > not NULL.Then when we get that page and set page attribute like > set_memory_uc and set_memory_wc, we hit error.
Could you explain your scenario with more details ? set_memory_* should be applied on mapped address. And in attempt to map your page (which was just kmap and kunmap'ed), it will overwrite the previous mappings.
Moreover, in my view, kmap_flush_unused is just helping us in keeping the cache clean for kmap virtual addresses if they are unmapped. Is it serving any more purpose here ?
> > fix: For that scenario,when we get the allocated page and its virtual > address is not NULL, we would like first flush that page. > So need export that function kmap_flush_unused. > > Signed-off-by: sha, ruibin <ruibin.sha@intel.com> > > --- > mm/highmem.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/highmem.c b/mm/highmem.c > index b32b70c..511299b 100644 > --- a/mm/highmem.c > +++ b/mm/highmem.c > @@ -156,6 +156,7 @@ void kmap_flush_unused(void) > flush_all_zero_pkmaps(); > unlock_kmap(); > } > +EXPORT_SYMBOL(kmap_flush_unused); This symbol is already extern'ed. Is it not sufficient for your case ? > > static inline unsigned long map_new_virtual(struct page *page) > { > -- > 1.7.9.5 > > Best Regards > > --------------------------------------------------------------- > > Sha, Rui bin ( Robin ) > > +86 13817890945 > > Android System Integration Shanghai >
-- Chintan Pandya
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