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Sun, 13 Nov 2016 21:46:40 -0800 (PST) Received: from linaro.org ([121.95.100.191]) by smtp.googlemail.com with ESMTPSA id q27sm6226739pfd.49.2016.11.13.21.46.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 13 Nov 2016 21:46:39 -0800 (PST) Date: Mon, 14 Nov 2016 14:55:16 +0900 From: AKASHI Takahiro To: Dennis Chen , Will Deacon Subject: Re: [PATCH v27 1/9] memblock: add memblock_cap_memory_range() Message-ID: <20161114055515.GH381@linaro.org> Mail-Followup-To: AKASHI Takahiro , Dennis Chen , 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, nd@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> <20161111031903.GB15997@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20161111031903.GB15997@arm.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20161113_214701_850239_9051544B X-CRM114-Status: GOOD ( 33.93 ) X-Spam-Score: -2.7 (--) X-Spam-Report: SpamAssassin version 3.4.0 on bombadil.infradead.org summary: Content analysis details: (-2.7 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [2607:f8b0:400e:c00:0:0:0:22c listed in] [list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, geoff@infradead.org, catalin.marinas@arm.com, kexec@lists.infradead.org, linux-mm@kvack.org, james.morse@arm.com, bauerman@linux.vnet.ibm.com, akpm@linux-foundation.org, nd@arm.com, dyoung@redhat.com, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patch=linaro.org@lists.infradead.org On Fri, Nov 11, 2016 at 11:19:04AM +0800, Dennis Chen wrote: > 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 OK, but I found that the two functions have a bit different semantics in clipping memory range, in particular, when the range [base,base+size) goes across several regions with a gap. (This does not happen in my arm64 kdump, though.) That is, 'limit' in memblock_mem_limit_remove_map() means total size of available memory, while 'size' in memblock_cap_memory_range() indicates the size of _continuous_ memory range. So I added an extra argument, exact, to a common function to specify distinct behaviors. Confusing? Please see the patch below. If nobody objects to this merge, I will submit a whole patchset of kdump again. Thanks, -Takahiro AKASHI -- 2.10.0 ===>8=== > > > > Thanks, > > -Takahiro AKASHI > > > > > Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ===8<=== include/linux/memblock.h | 1 + mm/memblock.c | 91 +++++++++++++++++++++++++++++++++++------------- 2 files changed, 68 insertions(+), 24 deletions(-) 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..5f849a9 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -1473,9 +1473,10 @@ phys_addr_t __init_memblock memblock_end_of_DRAM(void) return (memblock.memory.regions[idx].base + memblock.memory.regions[idx].size); } -static phys_addr_t __init_memblock __find_max_addr(phys_addr_t limit) +static phys_addr_t __init_memblock __find_max_addr(phys_addr_t min, + phys_addr_t limit) { - phys_addr_t max_addr = (phys_addr_t)ULLONG_MAX; + phys_addr_t max_addr = (phys_addr_t)ULLONG_MAX, base, size; struct memblock_region *r; /* @@ -1484,11 +1485,22 @@ static phys_addr_t __init_memblock __find_max_addr(phys_addr_t limit) * of those regions, max_addr will keep original value ULLONG_MAX */ for_each_memblock(memory, r) { - if (limit <= r->size) { - max_addr = r->base + limit; + if (min >= r->base + r->size) + continue; + + if (r->base <= min) { + base = min; + size = r->base + r->size - min; + } else { + base = r->base; + size = r->size; + } + + if (limit <= size) { + max_addr = base + limit; break; } - limit -= r->size; + limit -= size; } return max_addr; @@ -1501,7 +1513,7 @@ void __init memblock_enforce_memory_limit(phys_addr_t limit) if (!limit) return; - max_addr = __find_max_addr(limit); + max_addr = __find_max_addr(0, limit); /* @limit exceeds the total size of the memory, do nothing */ if (max_addr == (phys_addr_t)ULLONG_MAX) @@ -1514,34 +1526,65 @@ void __init memblock_enforce_memory_limit(phys_addr_t limit) (phys_addr_t)ULLONG_MAX); } -void __init memblock_mem_limit_remove_map(phys_addr_t limit) +/* + * __memblock_cap_memory_range - cap memblock regions + * @base: lowest address to clip + * @size: size of memory range + * @exact: true or false + * + * If @exact is true, the exact range [@base, @base+@size) of memory with + * kernel direct mapping is clipped from memblock.memory. Otherwise, total + * of @size of memory is clipped starting from @base. + */ +static void __init __memblock_cap_memory_range(phys_addr_t base, + phys_addr_t size, bool exact) { - struct memblock_type *type = &memblock.memory; - phys_addr_t max_addr; - int i, ret, start_rgn, end_rgn; + int start_rgn, end_rgn; + int i, ret; - if (!limit) + if (!size) return; - max_addr = __find_max_addr(limit); + if (!exact) { + phys_addr_t max_addr; - /* @limit exceeds the total size of the memory, do nothing */ - if (max_addr == (phys_addr_t)ULLONG_MAX) - return; + max_addr = __find_max_addr(base, size); + /* @size exceeds the total size of the memory, do nothing */ + if (max_addr == (phys_addr_t)ULLONG_MAX) + return; + + /* recalc the size to clip the exact range [@base, max_addr) */ + size = max_addr - base; + } - ret = memblock_isolate_range(type, max_addr, (phys_addr_t)ULLONG_MAX, - &start_rgn, &end_rgn); + ret = memblock_isolate_range(&memblock.memory, base, size, + &start_rgn, &end_rgn); if (ret) return; - /* remove all the MAP regions above the limit */ - for (i = end_rgn - 1; i >= start_rgn; i--) { - if (!memblock_is_nomap(&type->regions[i])) - memblock_remove_region(type, i); - } + /* remove all the other 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, max_addr, - (phys_addr_t)ULLONG_MAX); + memblock_remove_range(&memblock.reserved, 0, base); + memblock_remove_range(&memblock.reserved, + base + size, (phys_addr_t)ULLONG_MAX); +} + +void __init memblock_mem_limit_remove_map(phys_addr_t limit) +{ + __memblock_cap_memory_range(0, limit, false); +} + +void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size) +{ + __memblock_cap_memory_range(base, size, true); } static int __init_memblock memblock_search(struct memblock_type *type, phys_addr_t addr)