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Peter Anvin" Subject: [PATCH v6 2/4] mm: remove x86-only restriction of movable_node Date: Mon, 7 Nov 2016 17:44:34 -0600 X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1478562276-25539-1-git-send-email-arbab@linux.vnet.ibm.com> References: <1478562276-25539-1-git-send-email-arbab@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16110723-0016-0000-0000-00000519F9C5 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006040; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000189; SDB=6.00777909; UDB=6.00374582; IPR=6.00555226; BA=6.00004861; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00013245; XFM=3.00000011; UTC=2016-11-07 23:44:41 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16110723-0017-0000-0000-0000346F519C Message-Id: <1478562276-25539-3-git-send-email-arbab@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2016-11-07_08:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1609300000 definitions=main-1611070434 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Stewart Smith , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Alistair Popple , "Aneesh Kumar K.V" , Bharata B Rao , Nathan Fontenot , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" In commit c5320926e370 ("mem-hotplug: introduce movable_node boot option"), the memblock allocation direction is changed to bottom-up and then back to top-down like this: 1. memblock_set_bottom_up(true), called by cmdline_parse_movable_node(). 2. memblock_set_bottom_up(false), called by x86's numa_init(). Even though (1) occurs in generic mm code, it is wrapped by #ifdef CONFIG_MOVABLE_NODE, which depends on X86_64. This means that when we extend CONFIG_MOVABLE_NODE to non-x86 arches, things will be unbalanced. (1) will happen for them, but (2) will not. This toggle was added in the first place because x86 has a delay between adding memblocks and marking them as hotpluggable. Since other arches do this marking either immediately or not at all, they do not require the bottom-up toggle. So, resolve things by moving (1) from cmdline_parse_movable_node() to x86's setup_arch(), immediately after the movable_node parameter has been parsed. Signed-off-by: Reza Arbab --- Documentation/kernel-parameters.txt | 2 +- arch/x86/kernel/setup.c | 24 ++++++++++++++++++++++++ mm/memory_hotplug.c | 20 -------------------- 3 files changed, 25 insertions(+), 21 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 37babf9..adcccd5 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2401,7 +2401,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. that the amount of memory usable for all allocations is not too small. - movable_node [KNL,X86] Boot-time switch to enable the effects + movable_node [KNL] Boot-time switch to enable the effects of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details. MTD_Partition= [MTD] diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 9c337b0..4cfba94 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -985,6 +985,30 @@ void __init setup_arch(char **cmdline_p) parse_early_param(); +#ifdef CONFIG_MEMORY_HOTPLUG + /* + * Memory used by the kernel cannot be hot-removed because Linux + * cannot migrate the kernel pages. When memory hotplug is + * enabled, we should prevent memblock from allocating memory + * for the kernel. + * + * ACPI SRAT records all hotpluggable memory ranges. But before + * SRAT is parsed, we don't know about it. + * + * The kernel image is loaded into memory at very early time. We + * cannot prevent this anyway. So on NUMA system, we set any + * node the kernel resides in as un-hotpluggable. + * + * Since on modern servers, one node could have double-digit + * gigabytes memory, we can assume the memory around the kernel + * image is also un-hotpluggable. So before SRAT is parsed, just + * allocate memory near the kernel image to try the best to keep + * the kernel away from hotpluggable memory. + */ + if (movable_node_is_enabled()) + memblock_set_bottom_up(true); +#endif + x86_report_nx(); /* after early param, so could get panic from serial */ diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index cad4b91..e43142c1 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1727,26 +1727,6 @@ static bool can_offline_normal(struct zone *zone, unsigned long nr_pages) static int __init cmdline_parse_movable_node(char *p) { #ifdef CONFIG_MOVABLE_NODE - /* - * Memory used by the kernel cannot be hot-removed because Linux - * cannot migrate the kernel pages. When memory hotplug is - * enabled, we should prevent memblock from allocating memory - * for the kernel. - * - * ACPI SRAT records all hotpluggable memory ranges. But before - * SRAT is parsed, we don't know about it. - * - * The kernel image is loaded into memory at very early time. We - * cannot prevent this anyway. So on NUMA system, we set any - * node the kernel resides in as un-hotpluggable. - * - * Since on modern servers, one node could have double-digit - * gigabytes memory, we can assume the memory around the kernel - * image is also un-hotpluggable. So before SRAT is parsed, just - * allocate memory near the kernel image to try the best to keep - * the kernel away from hotpluggable memory. - */ - memblock_set_bottom_up(true); movable_node_enabled = true; #else pr_warn("movable_node option not supported\n");