linux-kernel - [PATCH] nommu: Provide is_vmalloc

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Date:	Wed, 12 Mar 2008 16:51:31 +0900
From:	Paul Mundt <lethal@...ux-sh.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	David Howells <dhowells@...hat.com>,
	Greg Ungerer <gerg@...pgear.com>,
	Christoph Lameter <clameter@....com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] nommu: Provide is_vmalloc_addr() stub.

Introduced in commit-id 9e2779fa281cfda13ac060753d674bbcaa23367e and
ifdef'ed out for nommu in 8ca3ed87db062201e1fa15b64a9214e193fc3a8a, both
approaches end up breaking the nommu build in different ways. An
impressive feat for a 2-liner.

Current is_vmalloc_addr() users fall in to two camps:

	- Determining whether to use vfree()/kfree()
	- Whether to do vmlist traversal (only /proc/kcore).

Since we don't support /proc/kcore on nommu, that leaves the
vfree()/kfree() determination use cases. nommu vfree() happens to be a
wrapper to kfree() anyways, so is_vmalloc_addr() can always return 0
and end up with the right behaviour. 

Signed-off-by: Paul Mundt <lethal@...ux-sh.org>

---

 include/linux/mm.h |   13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 3f3ccfe..b695875 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -235,15 +235,22 @@ static inline int get_page_unless_zero(struct page *page)
 struct page *vmalloc_to_page(const void *addr);
 unsigned long vmalloc_to_pfn(const void *addr);
 
-#ifdef CONFIG_MMU
-/* Determine if an address is within the vmalloc range */
+/*
+ * Determine if an address is within the vmalloc range
+ *
+ * On nommu, vmalloc/vfree wrap through kmalloc/kfree directly, so there
+ * is no special casing required.
+ */
 static inline int is_vmalloc_addr(const void *x)
 {
+#ifdef CONFIG_MMU
 	unsigned long addr = (unsigned long)x;
 
 	return addr >= VMALLOC_START && addr < VMALLOC_END;
-}
+#else
+	return 0;
 #endif
+}
 
 static inline struct page *compound_head(struct page *page)
 {
--
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