Messages in this thread |  | | From | "Yang, Bin" <> | Subject | Re: [PATCH v3 5/5] x86/mm: add WARN_ON_ONCE() for wrong large page mapping | Date | Tue, 4 Sep 2018 06:32:59 +0000 |
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On Tue, 2018-09-04 at 00:27 +0200, Thomas Gleixner wrote: > On Tue, 21 Aug 2018, Bin Yang wrote: > > @@ -625,6 +625,7 @@ try_preserve_large_page(pte_t *kpte, unsigned long address, > > > > psize = page_level_size(level); > > pmask = page_level_mask(level); > > + addr = address & pmask; > > > > /* > > * Calculate the number of pages, which fit into this large > > @@ -636,6 +637,12 @@ try_preserve_large_page(pte_t *kpte, unsigned long address, > > cpa->numpages = numpages; > > > > /* > > + * The old pgprot should not have any protection bit. Otherwise, > > + * the existing mapping is wrong already. > > + */ > > + WARN_ON_ONCE(needs_static_protections(old_prot, addr, psize, old_pfn)); > > The check itself is fine, but it just emits a warning and goes on as if > nothing happened. > > We really want to think about a proper way to fix that up without overhead > for the sane case.
could we change it as below? I think it should be safe to split large page if current mapping is wrong already.
if (needs_static_protections(old_prot, addr, psize, old_pfn)) { WARN_ON_ONCE(1); goto out_unlock; }
> > Thanks, > > tglx
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