linux-kernel - [PATCH 4/4] NOMMU: Ignore mmap() address param as it is a hint

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Date:	Thu, 24 Sep 2009 12:33:48 +0100
From:	David Howells <dhowells@...hat.com>
To:	torvalds@...l.org, akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org, David Howells <dhowells@...hat.com>
Subject: [PATCH 4/4] NOMMU: Ignore mmap() address param as it is a hint

Ignore the address parameter given to NOMMU mmap() as it is a hint, rather
than giving an error if it's non-zero.  MAP_FIXED still gets an error.

Signed-off-by: David Howells <dhowells@...hat.com>
---

 mm/nommu.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)


diff --git a/mm/nommu.c b/mm/nommu.c
index bd94b5a..62ac312 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -866,7 +866,7 @@ static int validate_mmap_request(struct file *file,
 	int ret;
 
 	/* do the simple checks first */
-	if (flags & MAP_FIXED || addr) {
+	if (flags & MAP_FIXED) {
 		printk(KERN_DEBUG
 		       "%d: Can't do fixed-address/overlay mmap of RAM\n",
 		       current->pid);
@@ -1223,9 +1223,6 @@ unsigned long do_mmap_pgoff(struct file *file,
 
 	kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
 
-	if (!(flags & MAP_FIXED))
-		addr = round_hint_to_min(addr);
-
 	/* decide whether we should attempt the mapping, and if so what sort of
 	 * mapping */
 	ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
@@ -1235,6 +1232,9 @@ unsigned long do_mmap_pgoff(struct file *file,
 		return ret;
 	}
 
+	/* we ignore the address hint */
+	addr = 0;
+
 	/* we've determined that we can make the mapping, now translate what we
 	 * now know into VMA flags */
 	vm_flags = determine_vm_flags(file, prot, flags, capabilities);

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