From: Dave Hansen <dave.hansen@intel.com>
To: Baoquan He <bhe@redhat.com>
Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
pagupta@redhat.com, linux-mm@kvack.org,
kirill.shutemov@linux.intel.com
Subject: Re: [PATCH v3 2/4] mm/sparsemem: Defer the ms->section_mem_map clearing
Date: Mon, 9 Apr 2018 09:02:31 -0700 [thread overview]
Message-ID: <fa2bb08a-42cc-c0cc-31c0-39d6e14f6f92@intel.com> (raw)
In-Reply-To: <20180408065055.GA19345@localhost.localdomain>
On 04/07/2018 11:50 PM, Baoquan He wrote:
>> Should the " = 0" instead be clearing SECTION_MARKED_PRESENT or
>> something? That would make it easier to match the code up with the code
>> that it is effectively undoing.
>
> Not sure if I understand your question correctly. From memory_present(),
> information encoded into ms->section_mem_map including numa node,
> SECTION_IS_ONLINE and SECTION_MARKED_PRESENT. Not sure if it's OK to only
> clear SECTION_MARKED_PRESENT. People may wrongly check SECTION_IS_ONLINE
> and do something on this memory section?
What is mean is that, instead of:
ms->section_mem_map = 0;
we could literally do:
ms->section_mem_map &= ~SECTION_MARKED_PRESENT;
That does the same thing in practice, but makes the _intent_ much more
clear.
next prev parent reply other threads:[~2018-04-09 16:02 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-28 3:26 [PATCH v3 0/4] mm/sparse: Optimize memmap allocation during sparse_init() Baoquan He
2018-02-28 3:26 ` Baoquan He
2018-02-28 3:26 ` [PATCH v3 1/4] mm/sparse: Add a static variable nr_present_sections Baoquan He
2018-02-28 3:26 ` Baoquan He
2018-02-28 3:26 ` [PATCH v3 2/4] mm/sparsemem: Defer the ms->section_mem_map clearing Baoquan He
2018-02-28 3:26 ` Baoquan He
2018-04-06 14:23 ` Dave Hansen
2018-04-08 6:50 ` Baoquan He
2018-04-09 16:02 ` Dave Hansen [this message]
2018-04-10 0:26 ` Baoquan He
2018-02-28 3:26 ` [PATCH v3 3/4] mm/sparse: Add a new parameter 'data_unit_size' for alloc_usemap_and_memmap Baoquan He
2018-02-28 3:26 ` Baoquan He
2018-02-28 3:26 ` [PATCH v3 4/4] mm/sparse: Optimize memmap allocation during sparse_init() Baoquan He
2018-02-28 3:26 ` Baoquan He
2018-04-06 14:50 ` Dave Hansen
2018-04-08 8:20 ` Baoquan He
2018-04-09 2:07 ` Baoquan He
2018-04-11 15:48 ` Dave Hansen
2018-04-15 2:19 ` Baoquan He
2018-04-16 4:36 ` Dave Hansen
2018-04-05 22:08 ` [PATCH v3 0/4] " Andrew Morton
2018-04-06 11:05 ` Kirill A. Shutemov
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