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

From: Vlastimil Babka
Date: Fri Mar 11 2016 - 07:43:56 EST

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,

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>

Shouldn't __must_check trigger here?

well, __must_check is a misleading name. It doesn't actually enforce the
value is checked. It just has to be used and an assignment is
sufficient. I was discussing this without our gcc guy and he promissed
to look and try to come up with a different attribute which would
actually work like __must_check.