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From: Will Deacon <will@kernel.org>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: linux-mm@kvack.org, Vineet Gupta <vgupta@synopsys.com>,
	Russell King <linux@armlinux.org.uk>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	nouveau@lists.freedesktop.org,
	linux-snps-arc@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org,
	x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] mm/thp: Rename pmd_mknotpresent() as pmd_mknotvalid()
Date: Mon, 20 Apr 2020 22:03:55 +0100	[thread overview]
Message-ID: <20200420210354.GD29998@willie-the-truck> (raw)
In-Reply-To: <1584680057-13753-3-git-send-email-anshuman.khandual@arm.com>

On Fri, Mar 20, 2020 at 10:24:17AM +0530, Anshuman Khandual wrote:
> pmd_present() is expected to test positive after pmdp_mknotpresent() as the
> PMD entry still points to a valid huge page in memory. pmdp_mknotpresent()
> implies that given PMD entry is just invalidated from MMU perspective while
> still holding on to pmd_page() referred valid huge page thus also clearing
> pmd_present() test. This creates the following situation which is counter
> intuitive.
> 
> [pmd_present(pmd_mknotpresent(pmd)) = true]
> 
> This renames pmd_mknotpresent() as pmd_mknotvalid() reflecting the helper's
> functionality more accurately while changing the above mentioned situation
> as follows. This does not create any functional change.
> 
> [pmd_present(pmd_mknotvalid(pmd)) = true]
> 
> This is not applicable for platforms that define own pmdp_invalidate() via
> __HAVE_ARCH_PMDP_INVALIDATE. Suggestion for renaming came during a previous
> discussion here.

Bikeshed alert: maybe pmd_mkinvalid() would be better, given that this is
a one-trick pony for pmdp_invalidate()?

Will


  reply	other threads:[~2020-04-20 21:04 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-20  4:54 [PATCH 0/2] mm/thp: Rename pmd_mknotpresent() as pmd_mknotvalid() Anshuman Khandual
2020-03-20  4:54 ` [PATCH 1/2] powerpc/mm: Drop platform defined pmd_mknotpresent() Anshuman Khandual
2020-03-20  4:54 ` [PATCH 2/2] mm/thp: Rename pmd_mknotpresent() as pmd_mknotvalid() Anshuman Khandual
2020-04-20 21:03   ` Will Deacon [this message]
2020-04-20 23:27     ` Anshuman Khandual
2020-04-21  7:07       ` Will Deacon
2020-04-21  8:09         ` Anshuman Khandual
2020-03-29 13:42 ` [PATCH 0/2] " Anshuman Khandual
2020-03-30 22:51   ` Andrew Morton

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