From ab2e83ead4eca9e045daac4cbf66eb1e7a244bb2 Mon Sep 17 00:00:00 2001
From: Paul Mundt <lethal@linux-sh.org>
Date: Thu, 8 Jan 2009 12:04:48 +0000
Subject: [PATCH] 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>
---
mm/nommu.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/mm/nommu.c b/mm/nommu.c
index a6e8ccfbd400..60ed8375c986 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.
--
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