From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx203.postini.com [74.125.245.203]) by kanga.kvack.org (Postfix) with SMTP id DFB7C6B0148 for ; Thu, 4 Oct 2012 15:47:49 -0400 (EDT) Date: Thu, 04 Oct 2012 15:47:47 -0400 (EDT) Message-Id: <20121004.154747.650416442352280556.davem@davemloft.net> Subject: [PATCH v2 6/7] mm: thp: Use more portable PMD clearing sequenece in zap_huge_pmd(). From: David Miller Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, akpm@linux-foundation.org, aarcange@redhat.com, hannes@cmpxchg.org Invalidation sequences are handled in various ways on various architectures. One way, which sparc64 uses, is to let the set_*_at() functions accumulate pending flushes into a per-cpu array. Then the flush_tlb_range() et al. calls process the pending TLB flushes. In this regime, the __tlb_remove_*tlb_entry() implementations are essentially NOPs. The canonical PTE zap in mm/memory.c is: ptent = ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm); tlb_remove_tlb_entry(tlb, pte, addr); With a subsequent tlb_flush_mmu() if needed. Mirror this in the THP PMD zapping using: orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd); page = pmd_page(orig_pmd); tlb_remove_pmd_tlb_entry(tlb, pmd, addr); And we properly accomodate TLB flush mechanims like the one described above. Signed-off-by: David S. Miller --- mm/huge_memory.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 20eeb2b..2fa0c59 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -996,9 +996,10 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, if (__pmd_trans_huge_lock(pmd, vma) == 1) { struct page *page; pgtable_t pgtable; + pmd_t orig_pmd; pgtable = pgtable_trans_huge_withdraw(tlb->mm); - page = pmd_page(*pmd); - pmd_clear(pmd); + orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd); + page = pmd_page(orig_pmd); tlb_remove_pmd_tlb_entry(tlb, pmd, addr); page_remove_rmap(page); VM_BUG_ON(page_mapcount(page) < 0); -- 1.7.10.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org