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From: Oscar Salvador <osalvador@suse.de>
To: David Hildenbrand <david@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org,
	linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org,
	linux-sh@vger.kernel.org, x86@kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@suse.com>,
	Pavel Tatashin <pasha.tatashin@soleen.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Wei Yang <richardw.yang@linux.intel.com>
Subject: Re: [PATCH v6 10/10] mm/memory_hotplug: Cleanup __remove_pages()
Date: Tue, 4 Feb 2020 10:46:53 +0100
Message-ID: <20200204094652.GE6494@linux> (raw)
In-Reply-To: <20191006085646.5768-11-david@redhat.com>

On Sun, Oct 06, 2019 at 10:56:46AM +0200, David Hildenbrand wrote:
> Let's drop the basically unused section stuff and simplify.
> 
> Also, let's use a shorter variant to calculate the number of pages to
> the next section boundary.
> 
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Wei Yang <richardw.yang@linux.intel.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>

I have to confess that it took me while to wrap around my head
with the new min() change, but looks ok:

Reviewed-by: Oscar Salvador <osalvador@suse.de>

> ---
>  mm/memory_hotplug.c | 17 ++++++-----------
>  1 file changed, 6 insertions(+), 11 deletions(-)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 843481bd507d..2275240cfa10 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -490,25 +490,20 @@ static void __remove_section(unsigned long pfn, unsigned long nr_pages,
>  void __remove_pages(unsigned long pfn, unsigned long nr_pages,
>  		    struct vmem_altmap *altmap)
>  {
> +	const unsigned long end_pfn = pfn + nr_pages;
> +	unsigned long cur_nr_pages;
>  	unsigned long map_offset = 0;
> -	unsigned long nr, start_sec, end_sec;
>  
>  	map_offset = vmem_altmap_offset(altmap);
>  
>  	if (check_pfn_span(pfn, nr_pages, "remove"))
>  		return;
>  
> -	start_sec = pfn_to_section_nr(pfn);
> -	end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
> -	for (nr = start_sec; nr <= end_sec; nr++) {
> -		unsigned long pfns;
> -
> +	for (; pfn < end_pfn; pfn += cur_nr_pages) {
>  		cond_resched();
> -		pfns = min(nr_pages, PAGES_PER_SECTION
> -				- (pfn & ~PAGE_SECTION_MASK));
> -		__remove_section(pfn, pfns, map_offset, altmap);
> -		pfn += pfns;
> -		nr_pages -= pfns;
> +		/* Select all remaining pages up to the next section boundary */
> +		cur_nr_pages = min(end_pfn - pfn, -(pfn | PAGE_SECTION_MASK));
> +		__remove_section(pfn, cur_nr_pages, map_offset, altmap);
>  		map_offset = 0;
>  	}
>  }
> -- 
> 2.21.0
> 
> 

-- 
Oscar Salvador
SUSE L3


  reply index

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-06  8:56 [PATCH v6 00/10] mm/memory_hotplug: Shrink zones before removing memory David Hildenbrand
2019-10-06  8:56 ` [PATCH v6 01/10] mm/memunmap: Don't access uninitialized memmap in memunmap_pages() David Hildenbrand
2019-10-06 19:58   ` Damian Tometzki
2019-10-06 20:13     ` David Hildenbrand
2019-10-14  9:05   ` David Hildenbrand
2019-10-06  8:56 ` [PATCH v6 02/10] mm/memmap_init: Update variable name in memmap_init_zone David Hildenbrand
2019-10-06  8:56 ` [PATCH v6 03/10] mm/memory_hotplug: Don't access uninitialized memmaps in shrink_pgdat_span() David Hildenbrand
2019-10-14  9:31   ` David Hildenbrand
2019-10-06  8:56 ` [PATCH v6 04/10] mm/memory_hotplug: Don't access uninitialized memmaps in shrink_zone_span() David Hildenbrand
2019-10-14  9:32   ` David Hildenbrand
2019-10-14 19:17     ` Andrew Morton
2019-11-19 14:16       ` David Hildenbrand
2019-11-19 20:44         ` Andrew Morton
2019-10-06  8:56 ` [PATCH v6 05/10] mm/memory_hotplug: Shrink zones when offlining memory David Hildenbrand
2019-10-14  9:39   ` David Hildenbrand
2019-10-14 19:16     ` Andrew Morton
2019-10-27 22:45   ` David Hildenbrand
2019-11-30 23:21     ` Andrew Morton
2019-11-30 23:43       ` David Hildenbrand
2019-12-18 17:08       ` David Hildenbrand
2019-12-18 20:16         ` Andrew Morton
2019-12-03 15:10   ` Oscar Salvador
2019-12-03 15:27     ` David Hildenbrand
2019-10-06  8:56 ` [PATCH v6 06/10] mm/memory_hotplug: Poison memmap in remove_pfn_range_from_zone() David Hildenbrand
2019-10-16 14:01   ` David Hildenbrand
2020-02-04  8:59   ` Oscar Salvador
2019-10-06  8:56 ` [PATCH v6 07/10] mm/memory_hotplug: We always have a zone in find_(smallest|biggest)_section_pfn David Hildenbrand
2020-02-04  9:06   ` Oscar Salvador
2020-02-05  8:57   ` Wei Yang
2020-02-05  8:59     ` David Hildenbrand
2020-02-05  9:26       ` Wei Yang
2019-10-06  8:56 ` [PATCH v6 08/10] mm/memory_hotplug: Don't check for "all holes" in shrink_zone_span() David Hildenbrand
2020-02-04  9:13   ` Oscar Salvador
2020-02-04  9:20     ` David Hildenbrand
2020-02-04 14:25   ` Baoquan He
2020-02-04 14:42     ` David Hildenbrand
2020-02-05 12:43       ` Baoquan He
2020-02-05 13:20         ` David Hildenbrand
2020-02-05 13:34           ` Baoquan He
2020-02-05 13:38             ` David Hildenbrand
2020-02-05 14:12               ` Baoquan He
2020-02-05 14:16                 ` David Hildenbrand
2020-02-05 14:26                   ` Baoquan He
2020-02-05  9:59   ` Wei Yang
2020-02-05 14:48     ` Baoquan He
2020-02-05 22:56       ` Wei Yang
2020-02-05 23:08         ` Baoquan He
2020-02-05 23:26           ` Wei Yang
2020-02-05 23:30             ` Baoquan He
2020-02-05 23:34               ` Wei Yang
2020-02-05 14:54     ` David Laight
2020-02-05 14:55       ` David Hildenbrand
2019-10-06  8:56 ` [PATCH v6 09/10] mm/memory_hotplug: Drop local variables " David Hildenbrand
2020-02-04  9:26   ` Oscar Salvador
2020-02-04  9:29     ` David Hildenbrand
2020-02-05 10:07   ` Wei Yang
2019-10-06  8:56 ` [PATCH v6 10/10] mm/memory_hotplug: Cleanup __remove_pages() David Hildenbrand
2020-02-04  9:46   ` Oscar Salvador [this message]
2020-02-04 12:41     ` David Hildenbrand
2020-02-04 13:13       ` Segher Boessenkool
2020-02-04 13:38         ` David Hildenbrand
2020-02-05 12:51           ` Segher Boessenkool
2020-02-05 13:17             ` David Hildenbrand
2020-02-05 13:18               ` David Hildenbrand
2020-02-05 13:23                 ` David Hildenbrand
2020-02-05 11:48   ` Wei Yang
2019-12-02  9:09 ` [PATCH v6 00/10] mm/memory_hotplug: Shrink zones before removing memory David Hildenbrand
2019-12-03 13:36   ` Oscar Salvador
2020-01-31  4:40     ` Andrew Morton
2020-01-31  9:18       ` David Hildenbrand
2020-01-31 10:03         ` Michal Hocko
2020-01-31 10:36           ` David Hildenbrand
2020-02-04  1:46         ` Andrew Morton
2020-02-04  8:45           ` David Hildenbrand
2020-02-04  9:51             ` Oscar Salvador

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