Re: [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@arm.com>
Cc: Will Deacon <redacted>
Cc: James Morse <james.morse@arm.com>
Cc: Bhupesh Sharma <redacted>
Cc: David Hildenbrand <redacted>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Dave Kleikamp <redacted>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mike Rapoport <redacted>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Stefan Agner <stefan@agner.ch>
Cc: Laura Abbott <redacted>
Cc: Greg Hackmann <redacted>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kristina Martsenko <redacted>
Cc: CHANDAN VN <redacted>
Cc: AKASHI Takahiro <redacted>
Cc: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Matthias Brugger <mbrugger@suse.com>
Signed-off-by: David Hildenbrand <redacted>
---
 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