On Mon, Aug 16, 2010 at 07:19:58AM -0500, Christoph Lameter wrote: > On Mon, 16 Aug 2010, Naoya Horiguchi wrote: > > > In my understanding, in current code "other processors increasing refcount > > during migration" can happen both in non-hugepage direct I/O and in hugepage > > direct I/O in the similar way (i.e. get_user_pages_fast() from dio_refill_pages()). > > So I think there is no specific problem to hugepage. > > Or am I missing your point? > > With a single page there is the check of the refcount during migration > after all the references have been removed (at that point the page is no > longer mapped by any process and direct iO can no longer be > initiated without a page fault. The same checking mechanism works for hugeapge. > > I see that you are running try_to_unmap() from unmap_and_move_huge_page(). Yes, that's right. > > I dont see a patch adding huge page support to try_to_unmap though. How > does this work? I previously posted "hugetlb, rmap: add reverse mapping for hugepage" patch which enables try_to_unmap() to work on hugepage by enabling to handle anon_vma and mapcount for hugepage. For details refer to the following commit: commit 0fe6e20b9c4c53b3e97096ee73a0857f60aad43f Author: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> Date: Fri May 28 09:29:16 2010 +0900 hugetlb, rmap: add reverse mapping for hugepage (Current "Hugepage migration" patchset is based on 2.6.35-rc3. So I'll rebase it onto the latest release in the next post.) Thanks, Naoya Horiguchi -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>