From: Catalin Marinas <catalin.marinas@arm.com>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org,
will@kernel.org, akpm@linux-foundation.org,
Mark Rutland <mark.rutland@arm.com>,
Marc Zyngier <maz@kernel.org>,
Suzuki Poulose <suzuki.poulose@arm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] arm64/mm: Change THP helpers to comply with generic MM semantics
Date: Tue, 8 Sep 2020 12:32:11 +0100 [thread overview]
Message-ID: <20200908113210.GC25591@gaia> (raw)
In-Reply-To: <b29e2bda-3299-e69f-90cf-1c9bd59a219d@arm.com>
On Tue, Sep 08, 2020 at 03:48:08PM +0530, Anshuman Khandual wrote:
> On 09/03/2020 10:26 PM, Catalin Marinas wrote:
> > On Mon, Aug 17, 2020 at 02:49:43PM +0530, Anshuman Khandual wrote:
> >> pmd_present() and pmd_trans_huge() are expected to behave in the following
> >> manner during various phases of a given PMD. It is derived from a previous
> >> detailed discussion on this topic [1] and present THP documentation [2].
> >>
> >> pmd_present(pmd):
> >>
> >> - Returns true if pmd refers to system RAM with a valid pmd_page(pmd)
> >> - Returns false if pmd does not refer to system RAM - Invalid pmd_page(pmd)
> >
> > The second bullet doesn't make much sense. If you have a pmd mapping of
> > some I/O memory, pmd_present() still returns true (as does
> > pte_present()).
>
> Derived this from an earlier discussion (https://lkml.org/lkml/2018/10/17/231)
> but current representation here might not be accurate.
>
> Would this be any better ?
>
> pmd_present(pmd):
>
> - Returns true if pmd refers to system RAM with a valid pmd_page(pmd)
> - Returns false if pmd refers to a migration or swap entry
Yes, that's better
--
Catalin
next prev parent reply other threads:[~2020-09-08 11:32 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-17 9:19 [PATCH 0/2] arm64/mm: Enable THP migration Anshuman Khandual
2020-08-17 9:19 ` [PATCH 1/2] arm64/mm: Change THP helpers to comply with generic MM semantics Anshuman Khandual
2020-08-18 9:13 ` Jonathan Cameron
2020-08-18 9:41 ` Anshuman Khandual
2020-08-18 12:26 ` Jonathan Cameron
2020-08-19 9:10 ` Anshuman Khandual
2020-09-03 16:56 ` Catalin Marinas
2020-09-03 17:31 ` Ralph Campbell
2020-09-08 10:25 ` Anshuman Khandual
2020-09-08 10:18 ` Anshuman Khandual
2020-09-08 11:32 ` Catalin Marinas [this message]
2020-08-17 9:19 ` [PATCH 2/2] arm64/mm: Enable THP migration Anshuman Khandual
2020-09-03 16:58 ` Catalin Marinas
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