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 09:25:01 -0700 [thread overview]
Message-ID: <CA+55aFwHGgiog+wFFDLXKjs4zVjMp-FLduGsEr800F5ruJ_aRA@mail.gmail.com> (raw)
In-Reply-To: <577696D5.2010609@sr71.net>
On Fri, Jul 1, 2016 at 9:14 AM, Dave Hansen <dave@sr71.net> wrote:
>
> As I understand it, the erratum only affects a thread which is about to
> page fault. The write associated with the dirty bit being set never
> actually gets executed. So, the bit really *is* stray and isn't
> something we need to preserve.
Ok, good.
> Otherwise, we'd be really screwed because we couldn't ever simply clear it.
Oh, we could do the whole "clear the pte, then flush the tlb, then go
back and clear the stale dirty bits and move them into the backing
page".
I was afraid we might have to do something like that.
Linus
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prev parent reply other threads:[~2016-07-01 16:25 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
2016-07-01 16:14 ` Dave Hansen
2016-07-01 16:25 ` Linus Torvalds [this message]
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