Re: [PATCH] mm:bugfix check return value of ioremap_prot

[Alexey Dobriyan <adobriyan@gmail.com>]

On Thu, Aug 02, 2018 at 02:02:22PM -0700, Andrew Morton wrote:
> On Thu, 2 Aug 2018 09:47:52 -0700 Yang Shi <shy828301@gmail.com> wrote:
> 
> > On Thu, Aug 2, 2018 at 12:37 AM,  <chenjie6@huawei.com> wrote:
> > > From: chen jie <chen jie@chenjie6@huwei.com>
> > >
> > >         ioremap_prot can return NULL which could lead to an oops
> > 
> > What oops? You'd better to have the oops information in your commit log.
> 
> Doesn't matter much - the code is clearly buggy.
> 
> Looking at the callers, I have suspicions about
> fs/proc/base.c:environ_read().  It's assuming that access_remote_vm()
> returns an errno.  But it doesn't - it returns number of bytes copied.
> 
> Alexey, could you please take a look?  While in there, I'd suggest
> adding some return value documentation to __access_remote_vm() and
> access_remote_vm().  Thanks.

This is true: remote VM accessors return number of bytes copied
but ->access returns len/-E. Returning "int" is deceptive.