From: Arun KS <arunks@codeaurora.org>
To: unlisted-recipients:; (no To-header on input)
Cc: keescook@chromium.org, khlebnikov@yandex-team.ru,
minchan@kernel.org, getarunks@gmail.com,
gregkh@linuxfoundation.org, akpm@linux-foundation.org,
mhocko@kernel.org, vbabka@suse.cz, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, vatsa@codeaurora.org, willy@infradead.org,
Arun KS <arunks@codeaurora.org>
Subject: [PATCH v5 4/4] mm: Remove managed_page_count spinlock
Date: Tue, 13 Nov 2018 12:03:10 +0530 [thread overview]
Message-ID: <1542090790-21750-5-git-send-email-arunks@codeaurora.org> (raw)
In-Reply-To: <1542090790-21750-1-git-send-email-arunks@codeaurora.org>
Now that totalram_pages and managed_pages are atomic varibles, no need
of managed_page_count spinlock. The lock had really a weak consistency
guarantee. It hasn't been used for anything but the update but no reader
actually cares about all the values being updated to be in sync.
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
next prev parent reply other threads:[~2018-11-13 6:33 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-13 6:33 [PATCH v5 0/4] mm: convert totalram_pages, totalhigh_pages and managed pages to atomic Arun KS
2018-11-13 6:33 ` [PATCH v5 1/4] mm: reference totalram_pages and managed_pages once per function Arun KS
2018-11-13 14:52 ` David Hildenbrand
2018-11-14 19:20 ` Pavel Tatashin
2018-11-13 6:33 ` [PATCH v5 2/4] mm: convert zone->managed_pages to atomic variable Arun KS
2018-11-13 14:55 ` David Hildenbrand
2018-11-14 19:21 ` Pavel Tatashin
2018-11-13 6:33 ` [PATCH v5 3/4] mm: convert totalram_pages and totalhigh_pages variables to atomic Arun KS
2018-11-14 19:23 ` Pavel Tatashin
2018-11-13 6:33 ` Arun KS [this message]
2018-11-14 19:23 ` [PATCH v5 4/4] mm: Remove managed_page_count spinlock Pavel Tatashin
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