From: Piotr Kwapulinski Date: Thu, 14 Jan 2016 23:19:50 +0000 (-0800) Subject: mm/mmap.c: remove incorrect MAP_FIXED flag comparison from mmap_region X-Git-Tag: v4.5-rc1~94^2~55 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=bc36f7017c39d1fe3c01aecd09cb2fe14753be90;p=linux.git mm/mmap.c: remove incorrect MAP_FIXED flag comparison from mmap_region 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. Signed-off-by: Piotr Kwapulinski Acked-by: Michal Hocko Cc: Oleg Nesterov Cc: Chris Metcalf Reviewed-by: Naoya Horiguchi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/mmap.c b/mm/mmap.c index 9da9c27c33a2..c311bfd8005b 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))