On Fri, Aug 11, 2023 at 10:34:52AM +0200, Richard Weinberger wrote:
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Von: "Christoph Hellwig" hch@infradead.org On Thu, Aug 10, 2023 at 09:54:46PM +0200, Richard Weinberger wrote:
But why add the bounce buffering first if you can avoid it from the very beginning by just using kmap_local instead of adding a new caller for the deprecate kmap_atomic?
Because I want this fix also in all stable trees. kmap_local() is rather new. When back porting patch 1/7, bounce buffers and kmap_atomic() are needed anyway. By doing this in patch 1/7 I avoid backport troubles and keep the delta between upstream and stable trees minimal.
Just use plain kmap for the historic backports.
Hm, yes. For UBIblock kmap should be too expensive.
? kmap is a no-op for !highmem. And it will always be way cheaper than bounce buffering for the case where you are actually fed highmem pages.