On Mon, Nov 23, 2015 at 02:14:01PM -0800, Andrew Morton wrote: > On Mon, 23 Nov 2015 18:36:42 +0100 Piotr Kwapulinski <kwapulinski.piotr@xxxxxxxxx> 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? It was my intention. This comment is still valid, even after removing the condition. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>