From 616b8371539a6c487404c3b8fb04078016dab4ba Mon Sep 17 00:00:00 2001 From: Zi Yan Date: Fri, 8 Sep 2017 16:10:57 -0700 Subject: mm: thp: enable thp migration in generic path Add thp migration's core code, including conversions between a PMD entry and a swap entry, setting PMD migration entry, removing PMD migration entry, and waiting on PMD migration entries. This patch makes it possible to support thp migration. If you fail to allocate a destination page as a thp, you just split the source thp as we do now, and then enter the normal page migration. If you succeed to allocate destination thp, you enter thp migration. Subsequent patches actually enable thp migration for each caller of page migration by allowing its get_new_page() callback to allocate thps. [zi.yan@cs.rutgers.edu: fix gcc-4.9.0 -Wmissing-braces warning] Link: http://lkml.kernel.org/r/A0ABA698-7486-46C3-B209-E95A9048B22C@cs.rutgers.edu [akpm@linux-foundation.org: fix x86_64 allnoconfig warning] Signed-off-by: Zi Yan Acked-by: Kirill A. Shutemov Cc: "H. Peter Anvin" Cc: Anshuman Khandual Cc: Dave Hansen Cc: David Nellans Cc: Ingo Molnar Cc: Mel Gorman Cc: Minchan Kim Cc: Naoya Horiguchi Cc: Thomas Gleixner Cc: Vlastimil Babka Cc: Andrea Arcangeli Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_vma_mapped.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) (limited to 'mm/page_vma_mapped.c') diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c index 8ec6ba230bb9..3bd3008db4cb 100644 --- a/mm/page_vma_mapped.c +++ b/mm/page_vma_mapped.c @@ -138,16 +138,28 @@ restart: if (!pud_present(*pud)) return false; pvmw->pmd = pmd_offset(pud, pvmw->address); - if (pmd_trans_huge(*pvmw->pmd)) { + if (pmd_trans_huge(*pvmw->pmd) || is_pmd_migration_entry(*pvmw->pmd)) { pvmw->ptl = pmd_lock(mm, pvmw->pmd); - if (!pmd_present(*pvmw->pmd)) - return not_found(pvmw); if (likely(pmd_trans_huge(*pvmw->pmd))) { if (pvmw->flags & PVMW_MIGRATION) return not_found(pvmw); if (pmd_page(*pvmw->pmd) != page) return not_found(pvmw); return true; + } else if (!pmd_present(*pvmw->pmd)) { + if (thp_migration_supported()) { + if (!(pvmw->flags & PVMW_MIGRATION)) + return not_found(pvmw); + if (is_migration_entry(pmd_to_swp_entry(*pvmw->pmd))) { + swp_entry_t entry = pmd_to_swp_entry(*pvmw->pmd); + + if (migration_entry_to_page(entry) != page) + return not_found(pvmw); + return true; + } + } else + WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); + return not_found(pvmw); } else { /* THP pmd was split under us: handle on pte level */ spin_unlock(pvmw->ptl); -- cgit v1.2.3-70-g09d2