On 20.07.21 08:55, Huang Ying wrote:
Before the commit c5b5a3dd2c1f ("mm: thp: refactor NUMA fault handling"), the TLB flushing is done in do_huge_pmd_numa_page() itself via flush_tlb_range(). But after commit c5b5a3dd2c1f ("mm: thp: refactor NUMA fault handling"), the TLB flushing is done in migrate_pages() as in the following code path anyway. do_huge_pmd_numa_page migrate_misplaced_page migrate_pages So now, the TLB flushing code in do_huge_pmd_numa_page() becomes unnecessary. So the code is deleted in this patch to simplify the code. This is only code cleanup, there's no visible performance difference. Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx> Cc: Yang Shi <shy828301@xxxxxxxxx> Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx> Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx> Cc: Heiko Carstens <hca@xxxxxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx> Cc: Zi Yan <ziy@xxxxxxxxxx> --- mm/huge_memory.c | 26 -------------------------- 1 file changed, 26 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index afff3ac87067..9f21e44c9030 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1440,32 +1440,6 @@ vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf) goto out; }- /*- * Since we took the NUMA fault, we must have observed the !accessible - * bit. Make sure all other CPUs agree with that, to avoid them - * modifying the page we're about to migrate. - * - * Must be done under PTL such that we'll observe the relevant - * inc_tlb_flush_pending(). - * - * We are not sure a pending tlb flush here is for a huge page - * mapping or not. Hence use the tlb range variant - */ - if (mm_tlb_flush_pending(vma->vm_mm)) { - flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE); - /* - * change_huge_pmd() released the pmd lock before - * invalidating the secondary MMUs sharing the primary - * MMU pagetables (with ->invalidate_range()). The - * mmu_notifier_invalidate_range_end() (which - * internally calls ->invalidate_range()) in - * change_pmd_range() will run after us, so we can't - * rely on it here and we need an explicit invalidate. - */ - mmu_notifier_invalidate_range(vma->vm_mm, haddr, - haddr + HPAGE_PMD_SIZE); - } CC Paolo/KVM list so we also remove the mmu notifier here. Do we need those
now in migrate_pages? I am not an expert in that code, but I cant find an equivalent mmu_notifier in migrate_misplaced_pages. I might be totally wrong, just something that I noticed.
pmd = pmd_modify(oldpmd, vma->vm_page_prot); page = vm_normal_page_pmd(vma, haddr, pmd); if (!page)
