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Date: Wed, 5 Aug 2020 14:00:06 +0800
From: Baoquan He <bhe@...hat.com>
To: Mike Rapoport <rppt@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
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>,
Emil Renner Berthing <kernel@...il.dk>,
Ingo Molnar <mingo@...hat.com>,
Hari Bathini <hbathini@...ux.ibm.com>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Max Filippov <jcmvbkbc@...il.com>,
Michael Ellerman <mpe@...erman.id.au>,
Michal Simek <monstr@...str.eu>,
Mike Rapoport <rppt@...ux.ibm.com>,
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-arch@...r.kernel.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
Subject: Re: [PATCH v2 14/17] x86/setup: simplify reserve_crashkernel()
On 08/02/20 at 07:35pm, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@...ux.ibm.com>
>
> * Replace magic numbers with defines
> * Replace memblock_find_in_range() + memblock_reserve() with
> memblock_phys_alloc_range()
> * Stop checking for low memory size in reserve_crashkernel_low(). The
> allocation from limited range will anyway fail if there is no enough
> memory, so there is no need for extra traversal of memblock.memory
>
> Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
> ---
> arch/x86/kernel/setup.c | 40 ++++++++++++++--------------------------
> 1 file changed, 14 insertions(+), 26 deletions(-)
Applied this patch on top of 5.8, crashkernel reservation works well.
And the code change looks good.
Reviewed-by: Baoquan He <bhe@...hat.com>
>
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index d8de4053c5e8..d7ced6982524 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -419,13 +419,13 @@ static int __init reserve_crashkernel_low(void)
> {
> #ifdef CONFIG_X86_64
> unsigned long long base, low_base = 0, low_size = 0;
> - unsigned long total_low_mem;
> + unsigned long low_mem_limit;
> int ret;
>
> - total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
> + low_mem_limit = min(memblock_phys_mem_size(), CRASH_ADDR_LOW_MAX);
>
> /* crashkernel=Y,low */
> - ret = parse_crashkernel_low(boot_command_line, total_low_mem, &low_size, &base);
> + ret = parse_crashkernel_low(boot_command_line, low_mem_limit, &low_size, &base);
> if (ret) {
> /*
> * two parts from kernel/dma/swiotlb.c:
> @@ -443,23 +443,17 @@ static int __init reserve_crashkernel_low(void)
> return 0;
> }
>
> - low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
> + low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX);
> if (!low_base) {
> pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
> (unsigned long)(low_size >> 20));
> return -ENOMEM;
> }
>
> - ret = memblock_reserve(low_base, low_size);
> - if (ret) {
> - pr_err("%s: Error reserving crashkernel low memblock.\n", __func__);
> - return ret;
> - }
> -
> - pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System low RAM: %ldMB)\n",
> + pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (low RAM limit: %ldMB)\n",
> (unsigned long)(low_size >> 20),
> (unsigned long)(low_base >> 20),
> - (unsigned long)(total_low_mem >> 20));
> + (unsigned long)(low_mem_limit >> 20));
>
> crashk_low_res.start = low_base;
> crashk_low_res.end = low_base + low_size - 1;
> @@ -503,13 +497,13 @@ static void __init reserve_crashkernel(void)
> * unless "crashkernel=size[KMG],high" is specified.
> */
> if (!high)
> - crash_base = memblock_find_in_range(CRASH_ALIGN,
> - CRASH_ADDR_LOW_MAX,
> - crash_size, CRASH_ALIGN);
> + crash_base = memblock_phys_alloc_range(crash_size,
> + CRASH_ALIGN, CRASH_ALIGN,
> + CRASH_ADDR_LOW_MAX);
> if (!crash_base)
> - crash_base = memblock_find_in_range(CRASH_ALIGN,
> - CRASH_ADDR_HIGH_MAX,
> - crash_size, CRASH_ALIGN);
> + crash_base = memblock_phys_alloc_range(crash_size,
> + CRASH_ALIGN, CRASH_ALIGN,
> + CRASH_ADDR_HIGH_MAX);
> if (!crash_base) {
> pr_info("crashkernel reservation failed - No suitable area found.\n");
> return;
> @@ -517,19 +511,13 @@ static void __init reserve_crashkernel(void)
> } else {
> unsigned long long start;
>
> - start = memblock_find_in_range(crash_base,
> - crash_base + crash_size,
> - crash_size, 1 << 20);
> + start = memblock_phys_alloc_range(crash_size, SZ_1M, crash_base,
> + crash_base + crash_size);
> if (start != crash_base) {
> pr_info("crashkernel reservation failed - memory is in use.\n");
> return;
> }
> }
> - ret = memblock_reserve(crash_base, crash_size);
> - if (ret) {
> - pr_err("%s: Error reserving crashkernel memblock.\n", __func__);
> - return;
> - }
>
> if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
> memblock_free(crash_base, crash_size);
> --
> 2.26.2
>
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