From: Anthony Iliopoulos <anthony.iliopoulos@huawei.com>
To: Oren Twaig <oren@scalemp.com>
Cc: Dave Hansen <dave@sr71.net>, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Shay Goikhman <shay.goikhman@huawei.com>,
Paul Mundt <paul.mundt@huawei.com>,
Carlos Villavieja <villavieja@hps.utexas.edu>,
Nacho Navarro <nacho.navarro@bsc.es>,
Avi Mendelson <avi.mendelson@tce.technion.ac.il>,
Yoav Etsion <yetsion@tce.technion.ac.il>,
Gerald Schaefer <gerald.schaefer@de.ibm.com>,
David Gibson <david@gibson.dropbear.id.au>,
linux-arch <linux-arch@vger.kernel.org>
Subject: Re: [PATCH] x86, hugetlb: add missing TLB page invalidation for hugetlb_cow()
Date: Sat, 17 May 2014 11:24:14 +0200 [thread overview]
Message-ID: <20140517092355.GA38103@server-36.huawei.corp> (raw)
In-Reply-To: <53746721.6060408@scalemp.com>
Hi Oren,
On Thu, May 15, 2014 at 10:05:05AM +0300, Oren Twaig wrote:
>
> On 05/15/2014 08:00 PM, Anthony Iliopoulos wrote:
> > I have dismissed this case, since I assume that there are many more
> > cycles spent in servicing the TLB invalidation IPI, walking the pgtable
> > plus other related overhead (e.g. sched) than in updating the pte/pmd
> > so I am not sure how possible it would be to hit this condition.
>
> Hi Anthony,
>
> I have a question about the above statement. What will happen with multi
> cpu VMs ? won't the race described above can happen ? I.e one virtual CPU
> can will visit the host and the other will continue to encounter your race ?
I don't think there will be any race for the vcpu cases, since the sptes
will be cleared via the mmu_notifier, so this should take care of it
in the same manner as ptep_get_and_clear() does, as described by Dave
earlier in this thread.
Regards,
Anthony
prev parent reply other threads:[~2014-05-17 9:25 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20140514092948.GA17391@server-36.huawei.corp>
2014-05-13 22:44 ` [PATCH] x86, hugetlb: add missing TLB page invalidation for hugetlb_cow() Dave Hansen
2014-05-15 17:00 ` Anthony Iliopoulos
2014-05-14 17:24 ` Dave Hansen
2014-05-15 7:05 ` Oren Twaig
2014-05-15 7:05 ` Oren Twaig
2014-05-17 9:24 ` Anthony Iliopoulos [this message]
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