Messages in this thread | | | Date | Tue, 27 Jul 2010 17:13:51 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [PATCH] Tight check of pfn_valid on sparsemem - v4 |
| |
On Tue, 27 Jul 2010 03:12:38 -0500 Milton Miller <miltonm@bga.com> wrote:
> > > > > +/* > > > > > + * Fill pg->private on valid mem_map with page itself. > > > > > + * pfn_valid() will check this later. (see include/linux/mmzone.h) > > > > > + * Every arch for supporting hole of mem_map should call > > > > > + * mark_valid_memmap(start, end). please see usage in ARM. > > > > > + */ > > > > > +void mark_valid_memmap(unsigned long start, unsigned long end) > > > > > +{ > > > > > + struct mem_section *ms; > > > > > + unsigned long pos, next; > > > > > + struct page *pg; > > > > > + void *memmap, *mapend; > > > > > + > > > > > + for (pos = start; pos < end; pos = next) { > > > > > + next = (pos + PAGES_PER_SECTION) & PAGE_SECTION_MASK; > > > > > + ms = __pfn_to_section(pos); > > > > > + if (!valid_section(ms)) > > > > > + continue; > > > > > + > > > > > + for (memmap = (void*)pfn_to_page(pos), > > > > > + /* The last page in section */ > > > > > + mapend = pfn_to_page(next-1); > > > > > + memmap < mapend; memmap += PAGE_SIZE) { > > > > > + pg = virt_to_page(memmap); > > > > > + set_page_private(pg, (unsigned long)pg); > > > > > + } > > > > > + } > > > > > +} > > Hmm, this loop would need to change for sections. And sizeof(struct > page) % PAGE_SIZE may not be 0, so we want a global symbol for sparsemem > too. IIUC, sizeof(struct page) % PAGE_SIZE is not a probelm.
> Perhaps the mem_section array. Using a symbol that is part of > the model pre-checks can remove a global symbol lookup and has the side > effect of making sure our pfn_valid is for the right model. >
But yes, maybe it's good to make use of a fixed-(magic)-value.
Tanks, -Kame
| |