On Tue 10-12-19 11:09:46, David Hildenbrand wrote: > On 10.12.19 11:04, Michal Hocko wrote: > > On Mon 09-12-19 12:43:40, Dan Williams wrote: > >> On Mon, Dec 9, 2019 at 12:24 PM Logan Gunthorpe <logang@xxxxxxxxxxxx> wrote: > >>> > >>> > >>> > >>> On 2019-12-09 12:23 p.m., David Hildenbrand wrote: > >>>> On 09.12.19 20:13, Logan Gunthorpe wrote: > > [...] > >>>>> #ifdef CONFIG_MEMORY_HOTPLUG > >>>>> -int arch_add_memory(int nid, u64 start, u64 size, > >>>>> +int arch_add_memory(int nid, u64 start, u64 size, pgprot_t prot, > >>>>> struct mhp_restrictions *restrictions) > >>>> > >>>> Can we fiddle that into "struct mhp_restrictions" instead? > >>> > >>> Yes, if that's what people want, it's pretty trivial to do. I chose not > >>> to do it that way because it doesn't get passed down to add_pages() and > >>> it's not really a "restriction". If I don't hear any objections, I will > >>> do that for v2. > >> > >> +1 to storing this information alongside the altmap in that structure. > >> However, I agree struct mhp_restrictions, with the MHP_MEMBLOCK_API > >> flag now gone, has lost all of its "restrictions". How about dropping > >> the 'flags' property and renaming the struct to 'struct > >> mhp_modifiers'? > > > > Hmm, this email somehow didn't end up in my inbox so I have missed it > > before replying. > > > > Well, mhp_modifiers makes some sense and it would reduce the API > > proliferation but how do you expect the prot part to be handled? > > I really do not want people to think about PAGE_KERNEL or which > > protection to use because my experience tells that this will get copied > > without much thinking or simply will break with some odd usecases. > > So how exactly this would be used? > > I was thinking about exactly the same "issue". > > 1. default initialization via a function > > memhp_modifier_default_init(&modified); > > 2. a flag that unlocks the prot field (default:0). Without the flag, it > is ignored. We can keep the current initialization then. > > Other ideas? 3. a prot mask to apply on top of PAGE_KERNEL? Or would that be insufficient/clumsy? -- Michal Hocko SUSE Labs
