Messages in this thread |  | | Date | Tue, 4 Sep 2018 09:49:00 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH v3 1/5] x86/mm: avoid redundant checking if pgprot has no change |
| |
On Tue, 4 Sep 2018, Yang, Bin wrote: > On Mon, 2018-09-03 at 23:57 +0200, Thomas Gleixner wrote: > > > > The last patch which does the overlap check is equally broken: > > Sorry that I did not understand the broken of last patch.
I meant 4/5 sorry. That's the one which introduces the overlap check and does this:
> > + /* > > + * Ensure that the requested pgprot does not violate static protection > > + * requirements. > > + */ > > + new_prot = static_protections(req_prot, address, > > + numpages << PAGE_SHIFT, pfn); > > > > It expands new_prot to the whole range even if the protections only > > overlap. That should not happen in practice, but we have no checks for that > > at all. > > Below code in patch #3 should cover this check. It will double check > new_prot in whole large page range.
Which is exactly what is wrong. Read again what I wrote.
Thanks,
tglx
|  |