linux-kernel - [PATCH] nommu: get_user_pages(): pin last page on non-page-aligned start

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Message-Id: <1267554584-24349-1-git-send-email-steve@digidescorp.com>
Date:	Tue,  2 Mar 2010 12:29:44 -0600
From:	"Steven J. Magnani" <steve@...idescorp.com>
To:	linux-mm@...ck.org
Cc:	linux-kernel@...r.kernel.org,
	"Steven J. Magnani" <steve@...idescorp.com>
Subject: [PATCH] nommu: get_user_pages(): pin last page on non-page-aligned start

The noMMU version of get_user_pages() fails to pin the last page
when the start address isn't page-aligned. The patch fixes this in a way
that makes find_extend_vma() congruent to its MMU cousin.

Signed-off-by: Steven J. Magnani <steve@...idescorp.com>
---
diff -uprN a/mm/nommu.c b/mm/nommu.c
--- a/mm/nommu.c	2010-03-01 16:37:31.000000000 -0600
+++ b/mm/nommu.c	2010-03-01 21:34:49.000000000 -0600
@@ -146,7 +146,7 @@ int __get_user_pages(struct task_struct 
 			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
 
 	for (i = 0; i < nr_pages; i++) {
-		vma = find_vma(mm, start);
+		vma = find_extend_vma(mm, start);
 		if (!vma)
 			goto finish_or_fault;
 
@@ -764,7 +764,7 @@ EXPORT_SYMBOL(find_vma);
  */
 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
 {
-	return find_vma(mm, addr);
+	return find_vma(mm, addr & PAGE_MASK);
 }
 
 /*

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