From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id 6F6CF280284 for ; Thu, 10 Nov 2016 22:19:17 -0500 (EST) Received: by mail-pf0-f200.google.com with SMTP id i88so3489834pfk.3 for ; Thu, 10 Nov 2016 19:19:17 -0800 (PST) Received: from EUR01-VE1-obe.outbound.protection.outlook.com (mail-ve1eur01on0048.outbound.protection.outlook.com. [104.47.1.48]) by mx.google.com with ESMTPS id v1si7876992pge.21.2016.11.10.19.19.16 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 10 Nov 2016 19:19:16 -0800 (PST) Date: Fri, 11 Nov 2016 11:19:04 +0800 From: Dennis Chen Subject: Re: [PATCH v27 1/9] memblock: add memblock_cap_memory_range() Message-ID: <20161111031903.GB15997@arm.com> References: <20161102044959.11954-1-takahiro.akashi@linaro.org> <20161102045153.12008-1-takahiro.akashi@linaro.org> <20161110172720.GB17134@arm.com> <20161111025049.GG381@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20161111025049.GG381@linaro.org> Sender: owner-linux-mm@kvack.org List-ID: To: AKASHI Takahiro , Will Deacon , catalin.marinas@arm.com, akpm@linux-foundation.org, james.morse@arm.com, geoff@infradead.org, bauerman@linux.vnet.ibm.com, dyoung@redhat.com, mark.rutland@arm.com, kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org On Fri, Nov 11, 2016 at 11:50:50AM +0900, AKASHI Takahiro wrote: > Will, > (+ Cc: Dennis) > > On Thu, Nov 10, 2016 at 05:27:20PM +0000, Will Deacon wrote: > > On Wed, Nov 02, 2016 at 01:51:53PM +0900, AKASHI Takahiro wrote: > > > Add memblock_cap_memory_range() which will remove all the memblock regions > > > except the range specified in the arguments. > > > > > > This function, like memblock_mem_limit_remove_map(), will not remove > > > memblocks with MEMMAP_NOMAP attribute as they may be mapped and accessed > > > later as "device memory." > > > See the commit a571d4eb55d8 ("mm/memblock.c: add new infrastructure to > > > address the mem limit issue"). > > > > > > This function is used, in a succeeding patch in the series of arm64 kdump > > > suuport, to limit the range of usable memory, System RAM, on crash dump > > > kernel. > > > (Please note that "mem=" parameter is of little use for this purpose.) > > > > > > Signed-off-by: AKASHI Takahiro > > > Cc: linux-mm@kvack.org > > > Cc: Andrew Morton > > > --- > > > include/linux/memblock.h | 1 + > > > mm/memblock.c | 28 ++++++++++++++++++++++++++++ > > > 2 files changed, 29 insertions(+) > > > > > > diff --git a/include/linux/memblock.h b/include/linux/memblock.h > > > index 5b759c9..0e770af 100644 > > > --- a/include/linux/memblock.h > > > +++ b/include/linux/memblock.h > > > @@ -334,6 +334,7 @@ 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_mem_limit_remove_map(phys_addr_t limit); > > > +void memblock_cap_memory_range(phys_addr_t base, phys_addr_t size); > > > bool memblock_is_memory(phys_addr_t addr); > > > int memblock_is_map_memory(phys_addr_t addr); > > > int memblock_is_region_memory(phys_addr_t base, phys_addr_t size); > > > diff --git a/mm/memblock.c b/mm/memblock.c > > > index 7608bc3..eb53876 100644 > > > --- a/mm/memblock.c > > > +++ b/mm/memblock.c > > > @@ -1544,6 +1544,34 @@ void __init memblock_mem_limit_remove_map(phys_addr_t limit) > > > (phys_addr_t)ULLONG_MAX); > > > } > > > > > > +void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size) > > > +{ > > > + int start_rgn, end_rgn; > > > + int i, ret; > > > + > > > + if (!size) > > > + return; > > > + > > > + ret = memblock_isolate_range(&memblock.memory, base, size, > > > + &start_rgn, &end_rgn); > > > + if (ret) > > > + return; > > > + > > > + /* remove all the MAP regions */ > > > + for (i = memblock.memory.cnt - 1; i >= end_rgn; i--) > > > + if (!memblock_is_nomap(&memblock.memory.regions[i])) > > > + memblock_remove_region(&memblock.memory, i); > > > + > > > + for (i = start_rgn - 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, base); > > > + memblock_remove_range(&memblock.reserved, > > > + base + size, (phys_addr_t)ULLONG_MAX); > > > +} > > > > This duplicates a bunch of the logic in memblock_mem_limit_remove_map. Can > > you not implement that in terms of your new, more general, function? e.g. > > by passing base == 0, and size == limit? > > Obviously it's possible. > I actually talked to Dennis before about merging them, > but he was against my idea. > Oops! I thought we have reached agreement in the thread:http://lists.infradead.org/pipermail/linux-arm-kernel/2016-July/442817.html So feel free to do that as Will'll do > > Thanks, > -Takahiro AKASHI > > > Will -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org