On Fri 20-11-15 17:42:14, 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. > It has no user visible effect. > > Remove the code that makes no sense. > > Signed-off-by: Piotr Kwapulinski <kwapulinski.pi...@gmail.com>
I think this is preferable. 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. I would prefer this to be in the changelog rather than/in addition to "It has no user visible effect" which is really vague. Acked-by: Michal Hocko <mho...@suse.com> > --- > I made a mistake in a changelog in a previous version of this patch. > I'm Sorry for the confusion. > This patch may be considered to be applied only in case the patch > "[PATCH v2 1/2] mm: fix incorrect behavior when process virtual > address space limit is exceeded" > is not going to be accepted. > > 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 > -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
