Subject: Re: [PATCH 1/1] mm, mpx: add "vm_flags_t vm_flags" arg to do_mmap_pgoff()

From: Mark Salter <[email-masked]>
Date: Mon, 27 Jul 2015 15:34:56 -0400

On Fri, 2015-07-24 at 10:39 -0400, Paul Gortmaker wrote:
> On Thu, Jul 16, 2015 at 6:26 PM, Oleg Nesterov <[email-masked]> wrote:
> > Add the additional "vm_flags_t vm_flags" argument to do_mmap_pgoff(),
> > rename it to do_mmap(), and re-introduce do_mmap_pgoff() as a simple
> > wrapper on top of do_mmap(). Perhaps we should update the callers of
> > do_mmap_pgoff() and kill it later.
> 
> It seems that the version of this patch in linux-next breaks all nommu
> builds (m86k, some arm, etc).
> 
> mm/nommu.c: In function 'do_mmap':
> mm/nommu.c:1248:30: error: 'vm_flags' redeclared as different kind of symbol
> mm/nommu.c:1241:15: note: previous definition of 'vm_flags' was here
> scripts/Makefile.build:258: recipe for target 'mm/nommu.o' failed
> 
> http://kisskb.ellerman.id.au/kisskb/buildresult/12470285/
> 
> Bisect says:
> 
> 31705a3a633bb63683918f055fe6032939672b61 is the first bad commit
> commit 31705a3a633bb63683918f055fe6032939672b61
> Author: Oleg Nesterov <[email-masked]>
> Date:   Fri Jul 24 09:20:30 2015 +1000
> 
>     mm, mpx: add "vm_flags_t vm_flags" arg to do_mmap_pgoff()
> 
> Paul.

This fixes the build error and runs fine on c6x:

diff --git a/mm/nommu.c b/mm/nommu.c
index 530eea5..af2196e 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1245,7 +1245,7 @@ unsigned long do_mmap(struct file *file,
 	struct vm_area_struct *vma;
 	struct vm_region *region;
 	struct rb_node *rb;
-	unsigned long capabilities, vm_flags, result;
+	unsigned long capabilities, result;
 	int ret;
 
 	*populate = 0;
@@ -1263,7 +1263,7 @@ unsigned long do_mmap(struct file *file,
 
 	/* 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);
+	vm_flags |= determine_vm_flags(file, prot, flags, capabilities);
 
 	/* we're going to need to record the mapping */
 	region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);