Messages in this thread | | | Date | Mon, 23 Nov 2015 14:14:01 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH v3] mm/mmap.c: remove incorrect MAP_FIXED flag comparison from mmap_region |
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On Mon, 23 Nov 2015 18:36:42 +0100 Piotr Kwapulinski <kwapulinski.piotr@gmail.com> 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. > > ... > > --- 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))
Did you intend to retain the stale comment?
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