Re: [PATCH 02/18] mm: make vm_mmap killable

From: Michal Hocko
Date: Fri Mar 11 2016 - 07:55:47 EST

On Fri 11-03-16 13:43:41, Vlastimil Babka wrote:
> On 03/11/2016 01:12 PM, Michal Hocko wrote:
> >On Fri 11-03-16 10:59:30, Vlastimil Babka wrote:
> >>On 02/29/2016 02:26 PM, Michal Hocko wrote:
> >>>From: Michal Hocko <mhocko@xxxxxxxx>
> >>>
> >>>All the callers of vm_mmap seem to check for the failure already
> >>>and bail out in one way or another on the error which means that
> >>
> >>Hmm I'm not that sure about this one:
> >> 17 1071 fs/binfmt_elf.c <<load_elf_binary>>
> >>
> >>Assigns result of vm_mmap() to "error" variable which is never checked.
> >
> >Yes it is not checked but not used either. If the current got killed
> >then it wouldn't return to the userspace so my understanding is that not
> >checking this value is not a problem. At least that is my understanding.
> Hmm, that's true. So,

I have updated the changelog and added the following note:
Please note that load_elf_binary is ignoring vm_mmap error for
current->personality & MMAP_PAGE_ZERO case but that shouldn't be a
problem because the address is not used anywhere and we never return to
the userspace if we got killed.

> Acked-by: Vlastimil Babka <vbabka@xxxxxxx>


Michal Hocko