linux-kernel - [PATCH v2 7/9] arm64: kdump: No need to mark crashkernel pages manually PG

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Date:   Mon, 14 Jan 2019 13:59:01 +0100
From:   David Hildenbrand <david@...hat.com>
To:     linux-mm@...ck.org
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-m68k@...ts.linux-m68k.org, linuxppc-dev@...ts.ozlabs.org,
        linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
        linux-mediatek@...ts.infradead.org,
        David Hildenbrand <david@...hat.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        James Morse <james.morse@....com>,
        Bhupesh Sharma <bhsharma@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Dave Kleikamp <dave.kleikamp@...cle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Michal Hocko <mhocko@...e.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Stefan Agner <stefan@...er.ch>,
        Laura Abbott <labbott@...hat.com>,
        Greg Hackmann <ghackmann@...roid.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Kristina Martsenko <kristina.martsenko@....com>,
        CHANDAN VN <chandan.vn@...sung.com>,
        AKASHI Takahiro <takahiro.akashi@...aro.org>,
        Logan Gunthorpe <logang@...tatee.com>
Subject: [PATCH v2 7/9] arm64: kdump: No need to mark crashkernel pages manually PG_reserved

The crashkernel is reserved via memblock_reserve(). memblock_free_all()
will call free_low_memory_core_early(), which will go over all reserved
memblocks, marking the pages as PG_reserved.

So manually marking pages as PG_reserved is not necessary, they are
already in the desired state (otherwise they would have been handed over
to the buddy as free pages and bad things would happen).

Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will.deacon@....com>
Cc: James Morse <james.morse@....com>
Cc: Bhupesh Sharma <bhsharma@...hat.com>
Cc: David Hildenbrand <david@...hat.com>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Dave Kleikamp <dave.kleikamp@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Mike Rapoport <rppt@...ux.vnet.ibm.com>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Florian Fainelli <f.fainelli@...il.com>
Cc: Stefan Agner <stefan@...er.ch>
Cc: Laura Abbott <labbott@...hat.com>
Cc: Greg Hackmann <ghackmann@...roid.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Kristina Martsenko <kristina.martsenko@....com>
Cc: CHANDAN VN <chandan.vn@...sung.com>
Cc: AKASHI Takahiro <takahiro.akashi@...aro.org>
Cc: Logan Gunthorpe <logang@...tatee.com>
Reviewed-by: Matthias Brugger <mbrugger@...e.com>
Signed-off-by: David Hildenbrand <david@...hat.com>
---
 arch/arm64/kernel/machine_kexec.c |  2 +-
 arch/arm64/mm/init.c              | 27 ---------------------------
 2 files changed, 1 insertion(+), 28 deletions(-)

diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
index 6f0587b5e941..66b5d697d943 100644
--- a/arch/arm64/kernel/machine_kexec.c
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -321,7 +321,7 @@ void crash_post_resume(void)
  * but does not hold any data of loaded kernel image.
  *
  * Note that all the pages in crash dump kernel memory have been initially
- * marked as Reserved in kexec_reserve_crashkres_pages().
+ * marked as Reserved as memory was allocated via memblock_reserve().
  *
  * In hibernation, the pages which are Reserved and yet "nosave" are excluded
  * from the hibernation iamge. crash_is_nosave() does thich check for crash
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 7205a9085b4d..c38976b70069 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -118,35 +118,10 @@ static void __init reserve_crashkernel(void)
 	crashk_res.start = crash_base;
 	crashk_res.end = crash_base + crash_size - 1;
 }
-
-static void __init kexec_reserve_crashkres_pages(void)
-{
-#ifdef CONFIG_HIBERNATION
-	phys_addr_t addr;
-	struct page *page;
-
-	if (!crashk_res.end)
-		return;
-
-	/*
-	 * To reduce the size of hibernation image, all the pages are
-	 * marked as Reserved initially.
-	 */
-	for (addr = crashk_res.start; addr < (crashk_res.end + 1);
-			addr += PAGE_SIZE) {
-		page = phys_to_page(addr);
-		SetPageReserved(page);
-	}
-#endif
-}
 #else
 static void __init reserve_crashkernel(void)
 {
 }
-
-static void __init kexec_reserve_crashkres_pages(void)
-{
-}
 #endif /* CONFIG_KEXEC_CORE */
 
 #ifdef CONFIG_CRASH_DUMP
@@ -586,8 +561,6 @@ void __init mem_init(void)
 	/* this will put all unused low memory onto the freelists */
 	memblock_free_all();
 
-	kexec_reserve_crashkres_pages();
-
 	mem_init_print_info(NULL);
 
 	/*
-- 
2.17.2