Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1275664

[PATCH v3] mm/mmap.c: remove incorrect MAP_FIXED flag comparison from mmap_region

Show all headers | View raw

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>
---
 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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH] mm: fix incorrect behavior when process virtual address space limit is exceeded Piotr Kwapulinski <kwapulinski.piotr@gmail.com> - 2015-11-16 18:40 +0100
  Re: [PATCH] mm: fix incorrect behavior when process virtual address  space limit is exceeded Michal Hocko <mhocko@kernel.org> - 2015-11-16 22:00 +0100
    Re: [PATCH] mm: fix incorrect behavior when process virtual address  space limit is exceeded Michal Hocko <mhocko@kernel.org> - 2015-11-17 01:40 +0100
    Re: [PATCH] mm: fix incorrect behavior when process virtual address  space limit is exceeded Cyril Hrubis <chrubis@suse.cz> - 2015-11-18 15:40 +0100
  Re: [PATCH] mm: fix incorrect behavior when process virtual  address space limit is exceeded Oleg Nesterov <oleg@redhat.com> - 2015-11-17 16:30 +0100
    Re: [PATCH] mm: fix incorrect behavior when process virtual  address space limit is exceeded Oleg Nesterov <oleg@redhat.com> - 2015-11-17 16:40 +0100
    [PATCH] mm/mmap.c: remove incorrect MAP_FIXED flag comparison from mmap_region Piotr Kwapulinski <kwapulinski.piotr@gmail.com> - 2015-11-17 18:30 +0100
      Re: [PATCH] mm/mmap.c: remove incorrect MAP_FIXED flag comparison  from mmap_region Andrew Morton <akpm@linux-foundation.org> - 2015-11-18 02:00 +0100
        Re: [PATCH] mm/mmap.c: remove incorrect MAP_FIXED flag comparison  from mmap_region Piotr Kwapulinski <kwapulinski.piotr@gmail.com> - 2015-11-18 17:30 +0100
          [PATCH v2 1/2] mm: fix incorrect behavior when process virtual address space limit is exceeded Piotr Kwapulinski <kwapulinski.piotr@gmail.com> - 2015-11-20 17:50 +0100
          [PATCH v2 2/2] mm/mmap.c: remove incorrect MAP_FIXED flag comparison from mmap_region Piotr Kwapulinski <kwapulinski.piotr@gmail.com> - 2015-11-20 17:50 +0100
            Re: [PATCH v2 2/2] mm/mmap.c: remove incorrect MAP_FIXED flag  comparison from mmap_region Michal Hocko <mhocko@kernel.org> - 2015-11-23 09:20 +0100
              [PATCH v3] mm/mmap.c: remove incorrect MAP_FIXED flag comparison from mmap_region Piotr Kwapulinski <kwapulinski.piotr@gmail.com> - 2015-11-23 18:40 +0100
                Re: [PATCH v3] mm/mmap.c: remove incorrect MAP_FIXED flag  comparison from mmap_region Andrew Morton <akpm@linux-foundation.org> - 2015-11-23 23:20 +0100
                Re: [PATCH v3] mm/mmap.c: remove incorrect MAP_FIXED flag comparison  from mmap_region Piotr Kwapulinski <kwapulinski.piotr@gmail.com> - 2015-11-24 17:20 +0100
                Re: [PATCH v3] mm/mmap.c: remove incorrect MAP_FIXED flag  comparison from mmap_region Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2015-11-27 06:30 +0100
    Re: [PATCH] mm: fix incorrect behavior when process virtual address  space limit is exceeded Chris Metcalf <cmetcalf@ezchip.com> - 2015-11-17 18:40 +0100
      Re: [PATCH] mm: fix incorrect behavior when process virtual  address space limit is exceeded Oleg Nesterov <oleg@redhat.com> - 2015-11-17 19:10 +0100

csiph-web