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From: Matthew Wilcox <willy@infradead.org>
To: Mike Rapoport <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Rick Edgecombe <rick.p.edgecombe@intel.com>,
	dave.hansen@intel.com, luto@kernel.org, linux-mm@kvack.org,
	x86@kernel.org, akpm@linux-foundation.org,
	linux-hardening@vger.kernel.org,
	kernel-hardening@lists.openwall.com, ira.weiny@intel.com,
	dan.j.williams@intel.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC 5/9] x86, mm: Use cache of page tables
Date: Thu, 6 May 2021 18:59:18 +0100	[thread overview]
Message-ID: <20210506175918.GC388843@casper.infradead.org> (raw)
In-Reply-To: <YJKK5RUMOzv488DO@kernel.org>

On Wed, May 05, 2021 at 03:09:09PM +0300, Mike Rapoport wrote:
> On Wed, May 05, 2021 at 10:51:55AM +0200, Peter Zijlstra wrote:
> > On Tue, May 04, 2021 at 05:30:28PM -0700, Rick Edgecombe wrote:
> > > @@ -54,6 +98,8 @@ void ___pte_free_tlb(struct mmu_gather *tlb, struct page *pte)
> > >  {
> > >  	pgtable_pte_page_dtor(pte);
> > >  	paravirt_release_pte(page_to_pfn(pte));
> > > +	/* Set Page Table so swap knows how to free it */
> > > +	__SetPageTable(pte);
> > >  	paravirt_tlb_remove_table(tlb, pte);
> > >  }
> > >  
> > > @@ -70,12 +116,16 @@ void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
> > >  	tlb->need_flush_all = 1;
> > >  #endif
> > >  	pgtable_pmd_page_dtor(page);
> > > +	/* Set Page Table so swap nows how to free it */
> > > +	__SetPageTable(virt_to_page(pmd));
> > >  	paravirt_tlb_remove_table(tlb, page);
> > >  }
> > >  
> > >  #if CONFIG_PGTABLE_LEVELS > 3
> > >  void ___pud_free_tlb(struct mmu_gather *tlb, pud_t *pud)
> > >  {
> > > +	/* Set Page Table so swap nows how to free it */
> > > +	__SetPageTable(virt_to_page(pud));
> > >  	paravirt_release_pud(__pa(pud) >> PAGE_SHIFT);
> > >  	paravirt_tlb_remove_table(tlb, virt_to_page(pud));
> > >  }
> > > @@ -83,6 +133,8 @@ void ___pud_free_tlb(struct mmu_gather *tlb, pud_t *pud)
> > >  #if CONFIG_PGTABLE_LEVELS > 4
> > >  void ___p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d)
> > >  {
> > > +	/* Set Page Table so swap nows how to free it */
> > > +	__SetPageTable(virt_to_page(p4d));
> > >  	paravirt_release_p4d(__pa(p4d) >> PAGE_SHIFT);
> > >  	paravirt_tlb_remove_table(tlb, virt_to_page(p4d));
> > >  }
> > 
> > This, to me, seems like a really weird place to __SetPageTable(), why
> > can't we do that on allocation?
> 
> We call __ClearPageTable() at pgtable_pxy_page_dtor(), so at least for pte
> and pmd we need to somehow tell release_pages() what kind of page it was.

One of the things I've been thinking about doing is removing the pgtable
dtors and instead calling the pgtable dtor in __put_page() if PageTable().
Might work nicely with this ...

  parent reply	other threads:[~2021-05-06 18:00 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-05  0:30 [PATCH RFC 0/9] PKS write protected " Rick Edgecombe
2021-05-05  0:30 ` [PATCH RFC 1/9] list: Support getting most recent element in list_lru Rick Edgecombe
2021-05-05  0:30 ` [PATCH RFC 2/9] list: Support list head not in object for list_lru Rick Edgecombe
2021-05-05  0:30 ` [PATCH RFC 3/9] x86/mm/cpa: Add grouped page allocations Rick Edgecombe
2021-05-05 12:08   ` Mike Rapoport
2021-05-05 13:09     ` Peter Zijlstra
2021-05-05 18:45       ` Mike Rapoport
2021-05-05 21:57         ` Edgecombe, Rick P
2021-05-09  9:39           ` Mike Rapoport
2021-05-10 19:38             ` Edgecombe, Rick P
2021-05-05  0:30 ` [PATCH RFC 4/9] mm: Explicitly zero page table lock ptr Rick Edgecombe
2021-05-05  0:30 ` [PATCH RFC 5/9] x86, mm: Use cache of page tables Rick Edgecombe
2021-05-05  8:51   ` Peter Zijlstra
2021-05-05 12:09     ` Mike Rapoport
2021-05-05 13:19       ` Peter Zijlstra
2021-05-05 21:54         ` Edgecombe, Rick P
2021-05-06 17:59       ` Matthew Wilcox [this message]
2021-05-06 18:24   ` Shakeel Butt
2021-05-07 16:27     ` Edgecombe, Rick P
2021-05-05  0:30 ` [PATCH RFC 6/9] x86/mm/cpa: Add set_memory_pks() Rick Edgecombe
2021-05-05  0:30 ` [PATCH RFC 7/9] x86/mm/cpa: Add perm callbacks to grouped pages Rick Edgecombe
2021-05-05  0:30 ` [PATCH RFC 8/9] x86, mm: Protect page tables with PKS Rick Edgecombe
2021-05-05  0:30 ` [PATCH RFC 9/9] x86, cpa: PKS protect direct map page tables Rick Edgecombe
2021-05-05  2:03 ` [PATCH RFC 0/9] PKS write protected " Ira Weiny
2021-05-05  6:25 ` Kees Cook
2021-05-05  8:37   ` Peter Zijlstra
2021-05-05 18:38     ` Kees Cook
2021-05-05 19:51   ` Edgecombe, Rick P
2021-05-06  0:00   ` Ira Weiny
2021-05-05 11:08 ` Vlastimil Babka
2021-05-05 11:56   ` Peter Zijlstra
2021-05-05 19:46     ` Edgecombe, Rick P

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