linux-kernel - Re: [PATCH 06/15] powerpc: fadamp: simplify fadump_reserve_crash

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Message-ID: <87d04d5hda.fsf@mpe.ellerman.id.au>
Date:   Thu, 30 Jul 2020 22:15:13 +1000
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Mike Rapoport <rppt@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Andy Lutomirski <luto@...nel.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Borislav Petkov <bp@...en8.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Christoph Hellwig <hch@....de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Max Filippov <jcmvbkbc@...il.com>,
        Michal Simek <monstr@...str.eu>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Mike Rapoport <rppt@...nel.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Mackerras <paulus@...ba.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Russell King <linux@...linux.org.uk>,
        Stafford Horne <shorne@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will@...nel.org>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        clang-built-linux@...glegroups.com,
        iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org, linux-c6x-dev@...ux-c6x.org,
        linux-kernel@...r.kernel.org, linux-mips@...r.kernel.org,
        linux-mm@...ck.org, linux-riscv@...ts.infradead.org,
        linux-s390@...r.kernel.org, linux-sh@...r.kernel.org,
        linux-xtensa@...ux-xtensa.org, linuxppc-dev@...ts.ozlabs.org,
        openrisc@...ts.librecores.org, sparclinux@...r.kernel.org,
        uclinux-h8-devel@...ts.sourceforge.jp, x86@...nel.org,
        Hari Bathini <hbathini@...ibm.com>
Subject: Re: [PATCH 06/15] powerpc: fadamp: simplify fadump_reserve_crash_area()

Mike Rapoport <rppt@...nel.org> writes:
> From: Mike Rapoport <rppt@...ux.ibm.com>
>
> fadump_reserve_crash_area() reserves memory from a specified base address
> till the end of the RAM.
>
> Replace iteration through the memblock.memory with a single call to
> memblock_reserve() with appropriate  that will take care of proper memory
                                     ^
                                     parameters?
> reservation.
>
> Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
> ---
>  arch/powerpc/kernel/fadump.c | 20 +-------------------
>  1 file changed, 1 insertion(+), 19 deletions(-)

I think this looks OK to me, but I don't have a setup to test it easily.
I've added Hari to Cc who might be able to.

But I'll give you an ack in the hope that it works :)

Acked-by: Michael Ellerman <mpe@...erman.id.au>


> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
> index 78ab9a6ee6ac..2446a61e3c25 100644
> --- a/arch/powerpc/kernel/fadump.c
> +++ b/arch/powerpc/kernel/fadump.c
> @@ -1658,25 +1658,7 @@ int __init fadump_reserve_mem(void)
>  /* Preserve everything above the base address */
>  static void __init fadump_reserve_crash_area(u64 base)
>  {
> -	struct memblock_region *reg;
> -	u64 mstart, msize;
> -
> -	for_each_memblock(memory, reg) {
> -		mstart = reg->base;
> -		msize  = reg->size;
> -
> -		if ((mstart + msize) < base)
> -			continue;
> -
> -		if (mstart < base) {
> -			msize -= (base - mstart);
> -			mstart = base;
> -		}
> -
> -		pr_info("Reserving %lluMB of memory at %#016llx for preserving crash data",
> -			(msize >> 20), mstart);
> -		memblock_reserve(mstart, msize);
> -	}
> +	memblock_reserve(base, memblock_end_of_DRAM() - base);
>  }
>  
>  unsigned long __init arch_reserved_kernel_pages(void)
> -- 
> 2.26.2