Re: [PATCH v2] MIPS: Remove race window in page fault handling

[Ralf Baechle <ralf@linux-mips.org>]

On Fri, Aug 15, 2014 at 10:03:47AM +0200, Lars Persson wrote:

> 
> On fre, 2014-08-08 at 22:47 +0200, Ralf Baechle wrote:
> > On Fri, Aug 08, 2014 at 09:55:00AM -0700, David Daney wrote:
> > 
> > > >+static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
> > > >+	pte_t *ptep, pte_t pteval);
> > > >+
> > > 
> > > Is it possible to reorder the code such that this declaration is not
> > > necessary?
> > 
> > That's not as obvious as one might think initially.  set_pte_at needs
> > to be defined after set_pte but before clear_pte which is calling set_pte_at.
> > 
> > Of both set_pte and clear_pte there are two #ifdefd variants.
> > 
> > set_pte_at is a fairly small function only but it's invoked quite a few
> > times so I was a little concerned about the effect on I'm experimenting with
> > outlining set_pte_at entirely.  ip22_defconfig with the patch applied as
> > posted; this is the effect on code size.
> > 
> >   text    data     bss     dec     hex filename
> > 3790118  175304   84544 4049966  3dcc2e vmlinux		as posted
> > 3789062	 175304	  84544	4048910	 3dc80e	vmlinux		set_pte_at outlined
> > 
> >   Ralf
> 
> Hi Ralf
> 
> Should I update the patch with outlined set_pte_at ?

Not necessary; I've already done that myself.  I was just waiting for
comments.

Thanks for your work on tracking this down.  I wonder, how did you discover
this issue?

  Ralf