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
WARNING: multiple messages have this Message-ID (diff)
From: Arun KS <arunks@codeaurora.org> 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: 16+ 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 ` 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 6:33 ` 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 6:33 ` 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 2018-11-13 6:33 ` Arun KS 2018-11-14 19:23 ` Pavel Tatashin 2018-11-13 6:33 ` Arun KS [this message] 2018-11-13 6:33 ` [PATCH v5 4/4] mm: Remove managed_page_count spinlock Arun KS 2018-11-14 19:23 ` Pavel Tatashin
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