From: David Howells Date: Sat, 16 Jan 2010 01:01:34 +0000 (-0800) Subject: nommu: remove a superfluous check of vm_region::vm_usage X-Git-Tag: v2.6.33-rc5~37 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=779c10232ceb11c1b259232c4845cfb2850287b7;p=platform%2Fupstream%2Fkernel-adaptation-pc.git nommu: remove a superfluous check of vm_region::vm_usage In split_vma(), there's no need to check if the VMA being split has a region that's in use by more than one VMA because: (1) The preceding test prohibits splitting of non-anonymous VMAs and regions (eg: file or chardev backed VMAs). (2) Anonymous regions can't be mapped multiple times because there's no handle by which to refer to the already existing region. (3) If a VMA has previously been split, then the region backing it has also been split into two regions, each of usage 1. Signed-off-by: David Howells Acked-by: Al Viro Cc: Greg Ungerer Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/nommu.c b/mm/nommu.c index 5e39294..d6dd656 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -1441,10 +1441,9 @@ int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, kenter(""); - /* we're only permitted to split anonymous regions that have a single - * owner */ - if (vma->vm_file || - vma->vm_region->vm_usage != 1) + /* we're only permitted to split anonymous regions (these should have + * only a single usage on the region) */ + if (vma->vm_file) return -ENOMEM; if (mm->map_count >= sysctl_max_map_count)