From: Linus Torvalds <torvalds@linux-foundation.org>
To: Dave Hansen <dave@sr71.net>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
the arch/x86 maintainers <x86@kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Borislav Petkov <bp@alien8.de>, Andi Kleen <ak@linux.intel.com>,
Michal Hocko <mhocko@suse.com>,
Dave Hansen <dave.hansen@linux.intel.com>
Subject: Re: [PATCH 6/6] x86: Fix stray A/D bit setting into non-present PTEs
Date: Fri, 1 Jul 2016 09:07:10 -0700 [thread overview]
Message-ID: <CA+55aFw8nwUAgqMy8LMEKg7roTWazR1gz+DkROgRbUHseDTk1g@mail.gmail.com> (raw)
In-Reply-To: <5775F418.2000803@sr71.net>
On Thu, Jun 30, 2016 at 9:39 PM, Dave Hansen <dave@sr71.net> wrote:
>
> I think what you suggest will work if we don't consider A/D in
> pte_none(). I think there are a bunch of code path where assume that
> !pte_present() && !pte_none() means swap.
Hmm.
Thinking about it some more, I still think it's a good idea to avoid
A/D bits in the swap entries and in pte_none() and friends, and it
might simplify some of this all.
But I also started worrying about us just losing sight of the dirty
bit in particular. It's not enough that we ignore the dirty bit - we'd
still want to make sure that the underlying backing page gets marked
dirty, even if the CPU is buggy and ends doing it "delayed" after
we've already unmapped the page.
So I get this feeling that we may need a fair chunk of your patch-series anyway.
Linus
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next prev parent reply other threads:[~2016-07-01 16:07 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-01 0:12 [PATCH 0/6] [v3] Workaround for Xeon Phi PTE A/D bits erratum Dave Hansen
2016-07-01 0:12 ` [PATCH 1/6] x86: fix duplicated X86_BUG(9) macro Dave Hansen
2016-07-01 9:23 ` Borislav Petkov
2016-07-01 16:30 ` Andy Lutomirski
2016-07-01 16:46 ` Borislav Petkov
2016-07-03 14:36 ` Andy Lutomirski
2016-07-03 18:44 ` Borislav Petkov
2016-07-01 0:12 ` [PATCH 2/6] mm, tlb: add mmu_gather->saw_unset_a_or_d Dave Hansen
2016-07-01 0:12 ` [PATCH 3/6] mm: add force_batch_flush to mmu_gather Dave Hansen
2016-07-01 0:12 ` [PATCH 4/6] mm: move flush in madvise_free_pte_range() Dave Hansen
2016-07-01 0:12 ` [PATCH 5/6] mm: make tlb_flush_mmu_tlbonly() return whether it flushed Dave Hansen
2016-07-01 0:12 ` [PATCH 6/6] x86: Fix stray A/D bit setting into non-present PTEs Dave Hansen
2016-07-01 1:50 ` Nadav Amit
2016-07-01 1:54 ` Dave Hansen
2016-07-01 2:55 ` Linus Torvalds
2016-07-01 3:06 ` Brian Gerst
2016-07-01 3:21 ` Linus Torvalds
2016-07-03 17:10 ` Dave Hansen
2016-07-01 4:39 ` Dave Hansen
2016-07-01 5:43 ` Linus Torvalds
2016-07-01 14:25 ` Eric W. Biederman
2016-07-01 15:51 ` Dave Hansen
2016-07-01 18:12 ` Eric W. Biederman
2016-07-01 16:07 ` Linus Torvalds [this message]
2016-07-01 16:14 ` Dave Hansen
2016-07-01 16:25 ` Linus Torvalds
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