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From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Mike Rapoport <rppt@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Kefeng Wang <wangkefeng.wang@huawei.com>,
	Mike Rapoport <rppt@linux.ibm.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 3/3] arm: extend pfn_valid to take into accound freed memory map alignment
Date: Tue, 18 May 2021 10:44:27 +0100	[thread overview]
Message-ID: <20210518094427.GR12395@shell.armlinux.org.uk> (raw)
In-Reply-To: <20210518090613.21519-4-rppt@kernel.org>

On Tue, May 18, 2021 at 12:06:13PM +0300, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@linux.ibm.com>
> 
> When unused memory map is freed the preserved part of the memory map is
> extended to match pageblock boundaries because lots of core mm
> functionality relies on homogeneity of the memory map within pageblock
> boundaries.
> 
> Since pfn_valid() is used to check whether there is a valid memory map
> entry for a PFN, make it return true also for PFNs that have memory map
> entries even if there is no actual memory populated there.

I thought pfn_valid() was a particularly hot path... do we really want
to be doing multiple lookups here? Is there no better solution?

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

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WARNING: multiple messages have this Message-ID (diff)
From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Mike Rapoport <rppt@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Kefeng Wang <wangkefeng.wang@huawei.com>,
	Mike Rapoport <rppt@linux.ibm.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 3/3] arm: extend pfn_valid to take into accound freed memory map alignment
Date: Tue, 18 May 2021 10:44:27 +0100	[thread overview]
Message-ID: <20210518094427.GR12395@shell.armlinux.org.uk> (raw)
In-Reply-To: <20210518090613.21519-4-rppt@kernel.org>

On Tue, May 18, 2021 at 12:06:13PM +0300, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@linux.ibm.com>
> 
> When unused memory map is freed the preserved part of the memory map is
> extended to match pageblock boundaries because lots of core mm
> functionality relies on homogeneity of the memory map within pageblock
> boundaries.
> 
> Since pfn_valid() is used to check whether there is a valid memory map
> entry for a PFN, make it return true also for PFNs that have memory map
> entries even if there is no actual memory populated there.

I thought pfn_valid() was a particularly hot path... do we really want
to be doing multiple lookups here? Is there no better solution?

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!


  reply	other threads:[~2021-05-18  9:49 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-18  9:06 [PATCH 0/3] memblock, arm: fixes for freeing of the memory map Mike Rapoport
2021-05-18  9:06 ` Mike Rapoport
2021-05-18  9:06 ` [PATCH 1/3] memblock: free_unused_memmap: use pageblock units instead of MAX_ORDER Mike Rapoport
2021-05-18  9:06   ` Mike Rapoport
2021-05-18  9:06 ` [PATCH 2/3] memblock: align freed memory map on pageblock boundaries with SPARSEMEM Mike Rapoport
2021-05-18  9:06   ` Mike Rapoport
2021-05-18  9:06 ` [PATCH 3/3] arm: extend pfn_valid to take into accound freed memory map alignment Mike Rapoport
2021-05-18  9:06   ` Mike Rapoport
2021-05-18  9:44   ` Russell King (Oracle) [this message]
2021-05-18  9:44     ` Russell King (Oracle)
2021-05-18 10:53     ` Mike Rapoport
2021-05-18 10:53       ` Mike Rapoport
2021-05-18 12:49   ` Kefeng Wang
2021-05-18 12:49     ` Kefeng Wang
2021-05-18 15:52     ` Mike Rapoport
2021-05-18 15:52       ` Mike Rapoport
2021-05-19  1:50       ` Kefeng Wang
2021-05-19  1:50         ` Kefeng Wang
2021-05-19 13:25         ` Mike Rapoport
2021-05-19 13:25           ` Mike Rapoport

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