linux-kernel - [RFC patch] mm: hugetlb: fix __unmap_hugepage

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Date:	Fri, 31 Oct 2014 12:22:12 +0800
From:	"Hillf Danton" <hillf.zj@...baba-inc.com>
To:	"'Michal Hocko'" <mhocko@...e.cz>
Cc:	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Hillf Danton" <hillf.zj@...baba-inc.com>,
	"linux-kernel" <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>
Subject: [RFC patch] mm: hugetlb: fix __unmap_hugepage_range

First, after flushing TLB, we have no need to scan pte from start again.
Second, before bail out loop, the address is forwarded one step.

Signed-off-by: Hillf Danton <hillf.zj@...baba-inc.com>
---

--- a/mm/hugetlb.c	Fri Oct 31 11:47:25 2014
+++ b/mm/hugetlb.c	Fri Oct 31 11:52:42 2014
@@ -2641,8 +2641,9 @@ void __unmap_hugepage_range(struct mmu_g
 
 	tlb_start_vma(tlb, vma);
 	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+	address = start;
 again:
-	for (address = start; address < end; address += sz) {
+	for (; address < end; address += sz) {
 		ptep = huge_pte_offset(mm, address);
 		if (!ptep)
 			continue;
@@ -2689,6 +2690,7 @@ again:
 		page_remove_rmap(page);
 		force_flush = !__tlb_remove_page(tlb, page);
 		if (force_flush) {
+			address += sz;
 			spin_unlock(ptl);
 			break;
 		}
--


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