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Thu, 06 Apr 2023 22:32:43 -0400 X-MC-Unique: LOeQWN3IPBC4g4DIOV7-TQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 214C7855420; Fri, 7 Apr 2023 02:32:43 +0000 (UTC) Received: from localhost (ovpn-12-86.pek2.redhat.com [10.72.12.86]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3EE6C140E94F; Fri, 7 Apr 2023 02:32:41 +0000 (UTC) Date: Fri, 7 Apr 2023 10:32:38 +0800 From: Baoquan He To: linux-kernel@vger.kernel.org Cc: catalin.marinas@arm.com, horms@kernel.org, thunder.leizhen@huawei.com, John.p.donnelly@oracle.com, will@kernel.org, kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v5] arm64: kdump: simplify the reservation behaviour of crashkernel=,high Message-ID: References: <20230407022419.19412-1-bhe@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20230407022419.19412-1-bhe@redhat.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230406_193248_517207_23855A9A X-CRM114-Status: GOOD ( 25.82 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 04/07/23 at 10:24am, Baoquan He wrote: ...... > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 66e70ca47680..307263c01292 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -69,6 +69,7 @@ phys_addr_t __ro_after_init arm64_dma_phys_limit; > > #define CRASH_ADDR_LOW_MAX arm64_dma_phys_limit > #define CRASH_ADDR_HIGH_MAX (PHYS_MASK + 1) > +#define CRASH_HIGH_SEARCH_BASE SZ_4G > > #define DEFAULT_CRASH_KERNEL_LOW_SIZE (128UL << 20) > > @@ -101,12 +102,13 @@ static int __init reserve_crashkernel_low(unsigned long long low_size) > */ > static void __init reserve_crashkernel(void) > { > - unsigned long long crash_base, crash_size; > - unsigned long long crash_low_size = 0; > + unsigned long long crash_base, crash_size, search_base; > unsigned long long crash_max = CRASH_ADDR_LOW_MAX; > + unsigned long long crash_low_size = 0; > char *cmdline = boot_command_line; > - int ret; > bool fixed_base = false; > + bool high = false; > + int ret; > > if (!IS_ENABLED(CONFIG_KEXEC_CORE)) > return; > @@ -129,7 +131,9 @@ static void __init reserve_crashkernel(void) > else if (ret) > return; > > + search_base = CRASH_HIGH_SEARCH_BASE; Here, I am hesitant if a conditional check is needed as below. On special system where both CONFIG_ZONE_DMA and CONFIG_ZONE_DMA32 are disabled, there's only low memory, means its arm64_dma_phys_limit equals to (PHYS_MASK + 1). In this case, whatever the crashkernel= is, it can search the whole system memory for available crashkernel region. Maybe it's fine since it's not big deal, the memory regoin can be found anyway. crash_max = CRASH_ADDR_HIGH_MAX; if (crash_max != CRASH_ADDR_LOW_MAX) search_base = CRASH_HIGH_SEARCH_BASE; > + high = true; > } else if (ret || !crash_size) { > /* The specified value is invalid */ > return; > @@ -140,31 +144,51 @@ static void __init reserve_crashkernel(void) > /* User specifies base address explicitly. */ > if (crash_base) { > fixed_base = true; > + search_base = crash_base; > crash_max = crash_base + crash_size; > } > > retry: > crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN, > - crash_base, crash_max); > + search_base, crash_max); > if (!crash_base) { > /* > - * If the first attempt was for low memory, fall back to > - * high memory, the minimum required low memory will be > - * reserved later. > + * For crashkernel=size[KMG]@offset[KMG], print out failure > + * message if can't reserve the specified region. > */ > - if (!fixed_base && (crash_max == CRASH_ADDR_LOW_MAX)) { > + if (fixed_base) { > + pr_warn("crashkernel reservation failed - memory is in use.\n"); > + return; > + } > + > + /* > + * For crashkernel=size[KMG], if the first attempt was for > + * low memory, fall back to high memory, the minimum required > + * low memory will be reserved later. > + */ > + if (!high && crash_max == CRASH_ADDR_LOW_MAX) { > crash_max = CRASH_ADDR_HIGH_MAX; > + search_base = CRASH_ADDR_LOW_MAX; > crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; > goto retry; > } > > + /* > + * For crashkernel=size[KMG],high, if the first attempt was > + * for high memory, fall back to low memory. > + */ > + if (high && crash_max == CRASH_ADDR_HIGH_MAX) { > + crash_max = CRASH_ADDR_LOW_MAX; > + search_base = 0; > + goto retry; > + } > pr_warn("cannot allocate crashkernel (size:0x%llx)\n", > crash_size); > return; > } > > - if ((crash_base > CRASH_ADDR_LOW_MAX - crash_low_size) && > - crash_low_size && reserve_crashkernel_low(crash_low_size)) { > + if ((crash_base >= CRASH_ADDR_LOW_MAX) && crash_low_size && > + reserve_crashkernel_low(crash_low_size)) { > memblock_phys_free(crash_base, crash_size); > return; > } > -- > 2.34.1 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel