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

From: Alexander Duyck
Date: Tue Sep 04 2018 - 14:33:50 EST


From: Alexander Duyck <alexander.h.duyck@xxxxxxxxx>

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@xxxxxxxxx>
---
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