Re: [PATCHv6 06/10] x86/mm: Add sync_global_pgds() for configuration with 5-level paging

[Kirill A. Shutemov]

On Fri, Jun 02, 2017 at 05:50:34PM +0300, Andrey Ryabinin wrote:
> On 05/24/2017 12:54 PM, Kirill A. Shutemov wrote:
> > This basically restores slightly modified version of original
> > sync_global_pgds() which we had before folded p4d was introduced.
> > 
> > The only modification is protection against 'addr' overflow.
> > 
> > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> > ---
> >  arch/x86/mm/init_64.c | 39 +++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 39 insertions(+)
> > 
> > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> > index 95651dc58e09..ce410c05d68d 100644
> > --- a/arch/x86/mm/init_64.c
> > +++ b/arch/x86/mm/init_64.c
> > @@ -92,6 +92,44 @@ __setup("noexec32=", nonx32_setup);
> >   * When memory was added make sure all the processes MM have
> >   * suitable PGD entries in the local PGD level page.
> >   */
> > +#ifdef CONFIG_X86_5LEVEL
> > +void sync_global_pgds(unsigned long start, unsigned long end)
> > +{
> > +	unsigned long addr;
> > +
> > +	for (addr = start; addr <= end; addr += ALIGN(addr + 1, PGDIR_SIZE)) {
> 
>                                         addr = ALIGN(addr + 1, PGDIR_SIZE)

Ouch. Thanks for noticing this.

Strange that it haven't crashed anywhere in my tests.

-- 
 Kirill A. Shutemov