Messages in this thread Patch in this message | | | Date | Fri, 15 Feb 2008 19:37:36 -0800 | From | Andrew Morton <> | Subject | Re: [patch 3/6] mmu_notifier: invalidate_page callbacks |
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On Thu, 14 Feb 2008 22:49:02 -0800 Christoph Lameter <clameter@sgi.com> wrote:
> Two callbacks to remove individual pages as done in rmap code > > invalidate_page() > > Called from the inner loop of rmap walks to invalidate pages. > > age_page() > > Called for the determination of the page referenced status. > > If we do not care about page referenced status then an age_page callback > may be be omitted. PageLock and pte lock are held when either of the > functions is called.
The age_page mystery shallows.
It would be useful to have some rationale somewhere in the patchset for the existence of this callback.
> #include <asm/tlbflush.h> > > @@ -287,7 +288,8 @@ static int page_referenced_one(struct pa > if (vma->vm_flags & VM_LOCKED) { > referenced++; > *mapcount = 1; /* break early from loop */ > - } else if (ptep_clear_flush_young(vma, address, pte)) > + } else if (ptep_clear_flush_young(vma, address, pte) | > + mmu_notifier_age_page(mm, address)) > referenced++;
The "|" is obviously deliberate. But no explanation is provided telling us why we still call the callback if ptep_clear_flush_young() said the page was recently referenced. People who read your code will want to understand this.
> /* Pretend the page is referenced if the task has the > @@ -455,6 +457,7 @@ static int page_mkclean_one(struct page > > flush_cache_page(vma, address, pte_pfn(*pte)); > entry = ptep_clear_flush(vma, address, pte); > + mmu_notifier(invalidate_page, mm, address);
I just don't see how ths can be done if the callee has another thread in the middle of establishing IO against this region of memory. ->invalidate_page() _has_ to be able to block. Confused.
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