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SubjectRe: [PATCH v3 4/4] mm: Remove managed_page_count spinlock
On 2018-11-08 14:04, Michal Hocko wrote:
> On Thu 08-11-18 13:53:18, Arun KS wrote:
>> Now totalram_pages and managed_pages are atomic varibles. No need
>> of managed_page_count spinlock.
>
> As explained earlier. Please add a motivation here. Feel free to reuse
> wording from
> http://lkml.kernel.org/r/20181107103630.GF2453@dhcp22.suse.cz

Sure. Will add in next spin.

Regards,
Arun
>
>>
>> Signed-off-by: Arun KS <arunks@codeaurora.org>
>> Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
>> Acked-by: Michal Hocko <mhocko@suse.com>
>> Acked-by: Vlastimil Babka <vbabka@suse.cz>
>> ---
>> include/linux/mmzone.h | 6 ------
>> mm/page_alloc.c | 5 -----
>> 2 files changed, 11 deletions(-)
>>
>> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
>> index e73dc31..c71b4d9 100644
>> --- a/include/linux/mmzone.h
>> +++ b/include/linux/mmzone.h
>> @@ -428,12 +428,6 @@ struct zone {
>> * Write access to present_pages at runtime should be protected by
>> * mem_hotplug_begin/end(). Any reader who can't tolerant drift of
>> * present_pages should get_online_mems() to get a stable value.
>> - *
>> - * Read access to managed_pages should be safe because it's unsigned
>> - * long. Write access to zone->managed_pages and totalram_pages are
>> - * protected by managed_page_count_lock at runtime. Idealy only
>> - * adjust_managed_page_count() should be used instead of directly
>> - * touching zone->managed_pages and totalram_pages.
>> */
>> atomic_long_t managed_pages;
>> unsigned long spanned_pages;
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index f8b64cc..26c5e14 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -122,9 +122,6 @@
>> };
>> EXPORT_SYMBOL(node_states);
>>
>> -/* Protect totalram_pages and zone->managed_pages */
>> -static DEFINE_SPINLOCK(managed_page_count_lock);
>> -
>> atomic_long_t _totalram_pages __read_mostly;
>> EXPORT_SYMBOL(_totalram_pages);
>> unsigned long totalreserve_pages __read_mostly;
>> @@ -7065,14 +7062,12 @@ static int __init
>> cmdline_parse_movablecore(char *p)
>>
>> void adjust_managed_page_count(struct page *page, long count)
>> {
>> - spin_lock(&managed_page_count_lock);
>> atomic_long_add(count, &page_zone(page)->managed_pages);
>> totalram_pages_add(count);
>> #ifdef CONFIG_HIGHMEM
>> if (PageHighMem(page))
>> totalhigh_pages_add(count);
>> #endif
>> - spin_unlock(&managed_page_count_lock);
>> }
>> EXPORT_SYMBOL(adjust_managed_page_count);
>>
>> --
>> 1.9.1

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