From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Will Deacon <will.deacon@arm.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
Vineet Gupta <vgupta@synopsys.com>,
Russell King <linux@armlinux.org.uk>,
Catalin Marinas <catalin.marinas@arm.com>,
Ralf Baechle <ralf@linux-mips.org>,
"David S. Miller" <davem@davemloft.net>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Andrea Arcangeli <aarcange@redhat.com>,
linux-arch@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, mark.rutland@arm.com
Subject: Re: [HELP-NEEDED, PATCH 0/3] Do not loose dirty bit on THP pages
Date: Thu, 15 Jun 2017 15:06:49 +0530 [thread overview]
Message-ID: <2a54d607-6e46-3693-158b-5e8101010ce2@linux.vnet.ibm.com> (raw)
In-Reply-To: <20170615084851.if6sntxo5tswhlk5@node.shutemov.name>
On Thursday 15 June 2017 02:18 PM, Kirill A. Shutemov wrote:
> O
>> I am not suggesting we don't do the invalidate (the need for that is
>> documented in __split_huge_pmd_locked(). I am suggesting we need a new
>> interface, something like Andrea suggested.
>>
>> old_pmd = pmdp_establish(pmd_mknotpresent());
>>
>> instead of pmdp_invalidate(). We can then use this in scenarios where we
>> want to update pmd PTE entries, where right now we go through a pmdp_clear
>> and set_pmd path. We should really not do that for THP entries.
>
> Which cases are you talking about? When do we need to clear pmd and set
> later?
>
With the latest upstream I am finding the usage when we mark pte clean
page_mkclean_one . Also there is a similar usage in
migrate_misplaced_transhuge_page(). I haven't really verified whether
they do cause any race. But my suggestion is, we should avoid the usage
of set_pmd_at() unless we are creating a new pmd PTE entry. If we can
provide pmdp_establish() we can achieve that easily.
-aneesh
prev parent reply other threads:[~2017-06-15 9:37 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-14 13:51 [HELP-NEEDED, PATCH 0/3] Do not loose dirty bit on THP pages Kirill A. Shutemov
2017-06-14 13:51 ` [PATCH 1/3] x86/mm: Provide pmdp_mknotpresent() helper Kirill A. Shutemov
2017-06-14 16:09 ` Andrea Arcangeli
2017-06-15 4:43 ` kbuild test robot
2017-06-14 13:51 ` [PATCH 2/3] mm: Do not loose dirty and access bits in pmdp_invalidate() Kirill A. Shutemov
2017-06-15 8:48 ` kbuild test robot
2017-06-14 13:51 ` [PATCH 3/3] mm, thp: Do not loose dirty bit in __split_huge_pmd_locked() Kirill A. Shutemov
2017-06-14 14:18 ` Martin Schwidefsky
2017-06-14 15:31 ` Andrea Arcangeli
2017-06-15 8:46 ` Kirill A. Shutemov
2017-06-14 15:28 ` Aneesh Kumar K.V
2017-06-14 14:06 ` [HELP-NEEDED, PATCH 0/3] Do not loose dirty bit on THP pages Martin Schwidefsky
2017-06-14 15:25 ` Aneesh Kumar K.V
2017-06-14 16:55 ` Will Deacon
2017-06-14 17:00 ` Vlastimil Babka
2017-06-15 1:36 ` Aneesh Kumar K.V
2017-06-15 1:05 ` Aneesh Kumar K.V
2017-06-15 2:50 ` Aneesh Kumar K.V
2017-06-15 8:48 ` Kirill A. Shutemov
2017-06-15 9:36 ` Aneesh Kumar K.V [this message]
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