Thanks all for your review! On Fri, Mar 31, 2023 at 05:32:17PM +0200, Fabio M. De Francesco wrote: > Date: Fri, 31 Mar 2023 17:32:17 +0200 > From: "Fabio M. De Francesco" <fmdefrancesco@xxxxxxxxx> > Subject: Re: [PATCH v2 9/9] drm/i915: Use kmap_local_page() in > gem/i915_gem_execbuffer.c > > On venerd? 31 marzo 2023 13:30:20 CEST Tvrtko Ursulin wrote: > > On 31/03/2023 05:18, Ira Weiny wrote: > [snip] > > > However I am unsure if disabling pagefaulting is needed or not. Thomas, > > Matt, being the last to touch this area, perhaps you could have a look? > > Because I notice we have a fallback iomap path which still uses > > io_mapping_map_atomic_wc. So if kmap_atomic to kmap_local conversion is > > safe, does the iomap side also needs converting to > > io_mapping_map_local_wc? Or they have separate requirements? > > AFAIK, the requirements for io_mapping_map_local_wc() are the same as for > kmap_local_page(): the kernel virtual address is _only_ valid in the caller > context, and map/unmap nesting must be done in stack-based ordering (LIFO). > > I think a follow up patch could safely switch to io_mapping_map_local_wc() / > io_mapping_unmap_local_wc since the address is local to context. > > However, not being an expert, reading your note now I suspect that I'm missing > something. Can I ask why you think that page-faults disabling might be > necessary? About the disabling of pagefault here, could you please talk more about it? :-) >From previous discussions and commit history, I didn't find relevant information and I lack background knowledge about it... If we have the reason to diable pagefault, I will fix and refresh the new version. Thanks, Zhao > > Thanks, > > Fabio > > > Regards, > > > > Tvrtko > > >
