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Re: [PATCH] mm: fix incorrect behavior when process virtual address space limit is exceeded

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On 11/16, Piotr Kwapulinski wrote:
>
> @@ -1551,7 +1552,7 @@ 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))
> +		if (!(flags & MAP_FIXED))
>  			return -ENOMEM;

Agree, "vm_flags & MAP_FIXED" makes no sense and just wrong...

Can't we simply remove this check? Afaics it only helps to avoid
count_vma_pages_range() in the unlikely case when may_expand_vm() fails.
And without MAP_FIXED count_vma_pages_range() should be cheap,
find_vma_intersection() should fail.

And afaics arch/tile/mm/elf.c can use do_mmap(MAP_FIXED ...) rather than
mmap_region(), it can be changed by a separate patch. In this case we can
unexport mmap_region().


OTOH, I won't insist, this patch looks fine to me.

Oleg.

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[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

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