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[45.249.212.190]) by mx.google.com with ESMTPS id k70si9181095oih.18.2019.04.04.19.17.26 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 04 Apr 2019 19:17:27 -0700 (PDT) Received-SPF: pass (google.com: domain of chenzhou10@huawei.com designates 45.249.212.190 as permitted sender) client-ip=45.249.212.190; Authentication-Results: mx.google.com; spf=pass (google.com: domain of chenzhou10@huawei.com designates 45.249.212.190 as permitted sender) smtp.mailfrom=chenzhou10@huawei.com Received: from DGGEMS410-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 900A4657617139DA5EEF; Fri, 5 Apr 2019 10:17:21 +0800 (CST) Received: from [127.0.0.1] (10.177.131.64) by DGGEMS410-HUB.china.huawei.com (10.3.19.210) with Microsoft SMTP Server id 14.3.408.0; Fri, 5 Apr 2019 10:17:15 +0800 Subject: Re: [PATCH 2/3] arm64: kdump: support more than one crash kernel regions To: Mike Rapoport References: <20190403030546.23718-1-chenzhou10@huawei.com> <20190403030546.23718-3-chenzhou10@huawei.com> <20190403112929.GA7715@rapoport-lnx> <20190404144408.GA6433@rapoport-lnx> CC: , , , , , , , , , From: Chen Zhou Message-ID: <783b8712-ddb1-a52b-81ee-0c6a216e5b7d@huawei.com> Date: Fri, 5 Apr 2019 10:17:13 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <20190404144408.GA6433@rapoport-lnx> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.131.64] X-CFilter-Loop: Reflected X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi Mike, On 2019/4/4 22:44, Mike Rapoport wrote: > Hi, > > On Wed, Apr 03, 2019 at 09:51:27PM +0800, Chen Zhou wrote: >> Hi Mike, >> >> On 2019/4/3 19:29, Mike Rapoport wrote: >>> On Wed, Apr 03, 2019 at 11:05:45AM +0800, Chen Zhou wrote: >>>> After commit (arm64: kdump: support reserving crashkernel above 4G), >>>> there may be two crash kernel regions, one is below 4G, the other is >>>> above 4G. >>>> >>>> Crash dump kernel reads more than one crash kernel regions via a dtb >>>> property under node /chosen, >>>> linux,usable-memory-range = >>>> >>>> Signed-off-by: Chen Zhou >>>> --- >>>> arch/arm64/mm/init.c | 37 +++++++++++++++++++++++++------------ >>>> include/linux/memblock.h | 1 + >>>> mm/memblock.c | 40 ++++++++++++++++++++++++++++++++++++++++ >>>> 3 files changed, 66 insertions(+), 12 deletions(-) >>>> >>>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c >>>> index ceb2a25..769c77a 100644 >>>> --- a/arch/arm64/mm/init.c >>>> +++ b/arch/arm64/mm/init.c >>>> @@ -64,6 +64,8 @@ EXPORT_SYMBOL(memstart_addr); >>>> phys_addr_t arm64_dma_phys_limit __ro_after_init; >>>> >>>> #ifdef CONFIG_KEXEC_CORE >>>> +# define CRASH_MAX_USABLE_RANGES 2 >>>> + >>>> static int __init reserve_crashkernel_low(void) >>>> { >>>> unsigned long long base, low_base = 0, low_size = 0; >>>> @@ -346,8 +348,8 @@ static int __init early_init_dt_scan_usablemem(unsigned long node, >>>> const char *uname, int depth, void *data) >>>> { >>>> struct memblock_region *usablemem = data; >>>> - const __be32 *reg; >>>> - int len; >>>> + const __be32 *reg, *endp; >>>> + int len, nr = 0; >>>> >>>> if (depth != 1 || strcmp(uname, "chosen") != 0) >>>> return 0; >>>> @@ -356,22 +358,33 @@ static int __init early_init_dt_scan_usablemem(unsigned long node, >>>> if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells))) >>>> return 1; >>>> >>>> - usablemem->base = dt_mem_next_cell(dt_root_addr_cells, ®); >>>> - usablemem->size = dt_mem_next_cell(dt_root_size_cells, ®); >>>> + endp = reg + (len / sizeof(__be32)); >>>> + while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) { >>>> + usablemem[nr].base = dt_mem_next_cell(dt_root_addr_cells, ®); >>>> + usablemem[nr].size = dt_mem_next_cell(dt_root_size_cells, ®); >>>> + >>>> + if (++nr >= CRASH_MAX_USABLE_RANGES) >>>> + break; >>>> + } >>>> >>>> return 1; >>>> } >>>> >>>> static void __init fdt_enforce_memory_region(void) >>>> { >>>> - struct memblock_region reg = { >>>> - .size = 0, >>>> - }; >>>> - >>>> - of_scan_flat_dt(early_init_dt_scan_usablemem, ®); >>>> - >>>> - if (reg.size) >>>> - memblock_cap_memory_range(reg.base, reg.size); >>>> + int i, cnt = 0; >>>> + struct memblock_region regs[CRASH_MAX_USABLE_RANGES]; >>>> + >>>> + memset(regs, 0, sizeof(regs)); >>>> + of_scan_flat_dt(early_init_dt_scan_usablemem, regs); >>>> + >>>> + for (i = 0; i < CRASH_MAX_USABLE_RANGES; i++) >>>> + if (regs[i].size) >>>> + cnt++; >>>> + else >>>> + break; >>>> + if (cnt) >>>> + memblock_cap_memory_ranges(regs, cnt); >>> >>> Why not simply call memblock_cap_memory_range() for each region? >> >> Function memblock_cap_memory_range() removes all memory type ranges except specified range. >> So if we call memblock_cap_memory_range() for each region simply, there will be no usable-memory >> on kdump capture kernel. > > Thanks for the clarification. > I still think that memblock_cap_memory_ranges() is overly complex. > > How about doing something like this: > > Cap the memory range for [min(regs[*].start, max(regs[*].end)] and then > removing the range in the middle? Yes, that would be ok. But that would do one more memblock_cap_memory_range operation. That is, if there are n regions, we need to do (n + 1) operations, which doesn't seem to matter. I agree with you, your idea is better. Thanks, Chen Zhou > >> Thanks, >> Chen Zhou >> >>> >>>> } >>>> >>>> void __init arm64_memblock_init(void) >>>> diff --git a/include/linux/memblock.h b/include/linux/memblock.h >>>> index 47e3c06..aeade34 100644 >>>> --- a/include/linux/memblock.h >>>> +++ b/include/linux/memblock.h >>>> @@ -446,6 +446,7 @@ phys_addr_t memblock_start_of_DRAM(void); >>>> phys_addr_t memblock_end_of_DRAM(void); >>>> void memblock_enforce_memory_limit(phys_addr_t memory_limit); >>>> void memblock_cap_memory_range(phys_addr_t base, phys_addr_t size); >>>> +void memblock_cap_memory_ranges(struct memblock_region *regs, int cnt); >>>> void memblock_mem_limit_remove_map(phys_addr_t limit); >>>> bool memblock_is_memory(phys_addr_t addr); >>>> bool memblock_is_map_memory(phys_addr_t addr); >>>> diff --git a/mm/memblock.c b/mm/memblock.c >>>> index 28fa8926..1a7f4ee7c 100644 >>>> --- a/mm/memblock.c >>>> +++ b/mm/memblock.c >>>> @@ -1697,6 +1697,46 @@ void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size) >>>> base + size, PHYS_ADDR_MAX); >>>> } >>>> >>>> +void __init memblock_cap_memory_ranges(struct memblock_region *regs, int cnt) >>>> +{ >>>> + int start_rgn[INIT_MEMBLOCK_REGIONS], end_rgn[INIT_MEMBLOCK_REGIONS]; >>>> + int i, j, ret, nr = 0; >>>> + >>>> + for (i = 0; i < cnt; i++) { >>>> + ret = memblock_isolate_range(&memblock.memory, regs[i].base, >>>> + regs[i].size, &start_rgn[i], &end_rgn[i]); >>>> + if (ret) >>>> + break; >>>> + nr++; >>>> + } >>>> + if (!nr) >>>> + return; >>>> + >>>> + /* remove all the MAP regions */ >>>> + for (i = memblock.memory.cnt - 1; i >= end_rgn[nr - 1]; i--) >>>> + if (!memblock_is_nomap(&memblock.memory.regions[i])) >>>> + memblock_remove_region(&memblock.memory, i); >>>> + >>>> + for (i = nr - 1; i > 0; i--) >>>> + for (j = start_rgn[i] - 1; j >= end_rgn[i - 1]; j--) >>>> + if (!memblock_is_nomap(&memblock.memory.regions[j])) >>>> + memblock_remove_region(&memblock.memory, j); >>>> + >>>> + for (i = start_rgn[0] - 1; i >= 0; i--) >>>> + if (!memblock_is_nomap(&memblock.memory.regions[i])) >>>> + memblock_remove_region(&memblock.memory, i); >>>> + >>>> + /* truncate the reserved regions */ >>>> + memblock_remove_range(&memblock.reserved, 0, regs[0].base); >>>> + >>>> + for (i = nr - 1; i > 0; i--) >>>> + memblock_remove_range(&memblock.reserved, >>>> + regs[i].base, regs[i - 1].base + regs[i - 1].size); >>>> + >>>> + memblock_remove_range(&memblock.reserved, >>>> + regs[nr - 1].base + regs[nr - 1].size, PHYS_ADDR_MAX); >>>> +} >>>> + >>>> void __init memblock_mem_limit_remove_map(phys_addr_t limit) >>>> { >>>> phys_addr_t max_addr; >>>> -- >>>> 2.7.4 >>>> >>> >> >