Messages in this thread | | | From | Naoya Horiguchi <> | Subject | Re: [PATCH v3] mm/mmap.c: remove incorrect MAP_FIXED flag comparison from mmap_region | Date | Fri, 27 Nov 2015 05:27:39 +0000 |
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On Mon, Nov 23, 2015 at 06:36:42PM +0100, Piotr Kwapulinski wrote: > The following flag comparison in mmap_region makes no sense: > > if (!(vm_flags & MAP_FIXED)) > return -ENOMEM; > > The condition is always false and thus the above "return -ENOMEM" is never > executed. The vm_flags must not be compared with MAP_FIXED flag. > The vm_flags may only be compared with VM_* flags. > MAP_FIXED has the same value as VM_MAYREAD. > Hitting the rlimit is a slow path and find_vma_intersection should realize > that there is no overlapping VMA for !MAP_FIXED case pretty quickly. > > Remove the code that makes no sense. > > Signed-off-by: Piotr Kwapulinski <kwapulinski.piotr@gmail.com>
Looks good to me. Thank you.
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> --- > mm/mmap.c | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/mm/mmap.c b/mm/mmap.c > index 2ce04a6..42a8259 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -1551,9 +1551,6 @@ unsigned long mmap_region(struct file *file, unsigned long addr, > * MAP_FIXED may remove pages of mappings that intersects with > * requested mapping. Account for the pages it would unmap. > */ > - if (!(vm_flags & MAP_FIXED)) > - return -ENOMEM; > - > nr_pages = count_vma_pages_range(mm, addr, addr + len); > > if (!may_expand_vm(mm, (len >> PAGE_SHIFT) - nr_pages)) > -- > 2.6.2 >
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