linux-kernel - [PATCH 2/2] mm: Create non-atomic version of SetPageReserved for init use

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Date:   Tue, 04 Sep 2018 11:33:45 -0700
From:   Alexander Duyck <alexander.duyck@...il.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     alexander.h.duyck@...el.com, pavel.tatashin@...rosoft.com,
        mhocko@...e.com, akpm@...ux-foundation.org, mingo@...nel.org,
        kirill.shutemov@...ux.intel.com
Subject: [PATCH 2/2] mm: Create non-atomic version of SetPageReserved for
 init use

From: Alexander Duyck <alexander.h.duyck@...el.com>

It doesn't make much sense to use the atomic SetPageReserved at init time
when we are using memset to clear the memory and manipulating the page
flags via simple "&=" and "|=" operations in __init_single_page.

This patch adds a non-atomic version __SetPageReserved that can be used
during page init and shows about a 10% improvement in initialization times
on the systems I have available for testing.

Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
---
 include/linux/page-flags.h |    1 +
 mm/page_alloc.c            |    4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 74bee8cecf4c..57ec3fef7e9f 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -292,6 +292,7 @@ static inline int PagePoisoned(const struct page *page)
 
 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
 	__CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
+	__SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
 PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
 	__CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
 	__SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 05e983f42316..9c7d6e971630 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1231,7 +1231,7 @@ void __meminit reserve_bootmem_region(phys_addr_t start, phys_addr_t end)
 			/* Avoid false-positive PageTail() */
 			INIT_LIST_HEAD(&page->lru);
 
-			SetPageReserved(page);
+			__SetPageReserved(page);
 		}
 	}
 }
@@ -5518,7 +5518,7 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
 		page = pfn_to_page(pfn);
 		__init_single_page(page, pfn, zone, nid);
 		if (context == MEMMAP_HOTPLUG)
-			SetPageReserved(page);
+			__SetPageReserved(page);
 
 		/*
 		 * Mark the block movable so that blocks are reserved for