Messages in this thread | | | Date | Thu, 20 Jan 2022 04:27:35 +0000 | From | Matthew Wilcox <> | Subject | Re: [PATCH] vmap(): don't allow invalid pages |
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On Thu, Jan 20, 2022 at 09:07:11AM +0530, Anshuman Khandual wrote: > > > On 1/19/22 10:52 PM, Yury Norov wrote: > >> Why should not this just scan over the entire user provided struct page > >> array and make sure that all pages there in are valid via above method, > >> but in vmap() itself before calling vmap_pages_range(). Because seems > >> like a single invalid page detected in vmap_pages_pte_range() will > >> anyways abort the entire vmap(). This will also enable us to drop the > >> existing NULL check above. > > > > I can do this, but why is it any better than the current approach? > > Because it will just return on the first instance where the valid page > check fails, saving us some CPU cycles and an incomplete mapping ?
The valid page check is never intended to fail! If you're worried about the efficiency of doing this, you have seriously confused your priorities.
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