From: Paul Mundt <lethal@linux-sh.org>
Date: Thu, 8 Jan 2009 12:04:48 +0000 (+0000)
Subject: NOMMU: Teach kobjsize() about VMA regions.
X-Git-Tag: v2.6.29-rc1~22^2~1
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=ab2e83ead4eca9e045daac4cbf66eb1e7a244bb2;p=linux-2.6-omap-h63xx.git

NOMMU: Teach kobjsize() about VMA regions.

Now that we no longer use compound pages for all large allocations,
kobjsize() actively breaks things like binfmt_flat by always handing
back PAGE_SIZE for mmap'ed regions. Fix this up by looking up the
VMA region for non-compounds.

Ideally binfmt_flat wants to get rid of kobjsize() completely, but
this is an incremental step.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Mike Frysinger <vapier.adi@gmail.com>
---

diff --git a/mm/nommu.c b/mm/nommu.c
index a6e8ccfbd40..60ed8375c98 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -148,6 +148,20 @@ unsigned int kobjsize(const void *objp)
 	if (PageSlab(page))
 		return ksize(objp);
 
+	/*
+	 * If it's not a compound page, see if we have a matching VMA
+	 * region. This test is intentionally done in reverse order,
+	 * so if there's no VMA, we still fall through and hand back
+	 * PAGE_SIZE for 0-order pages.
+	 */
+	if (!PageCompound(page)) {
+		struct vm_area_struct *vma;
+
+		vma = find_vma(current->mm, (unsigned long)objp);
+		if (vma)
+			return vma->vm_end - vma->vm_start;
+	}
+
 	/*
 	 * The ksize() function is only guaranteed to work for pointers
 	 * returned by kmalloc(). So handle arbitrary pointers here.