From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6B7F0C433F5 for ; Mon, 18 Oct 2021 04:42:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5196260F24 for ; Mon, 18 Oct 2021 04:42:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230146AbhJREoO (ORCPT ); Mon, 18 Oct 2021 00:44:14 -0400 Received: from foss.arm.com ([217.140.110.172]:60490 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229481AbhJREoN (ORCPT ); Mon, 18 Oct 2021 00:44:13 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id DD31811D4; Sun, 17 Oct 2021 21:42:02 -0700 (PDT) Received: from [10.163.74.6] (unknown [10.163.74.6]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B181E3F73D; Sun, 17 Oct 2021 21:41:58 -0700 (PDT) Subject: Re: [PATCH] mm/migrate: rework hotplug_memory_notifier() stub To: Michal Hocko , Arnd Bergmann Cc: Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Dave Hansen , Stephen Rothwell , Arnd Bergmann , David Hildenbrand , Oscar Salvador , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20211013144029.2154629-1-arnd@kernel.org> From: Anshuman Khandual Message-ID: Date: Mon, 18 Oct 2021 10:11:57 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/14/21 2:12 PM, Michal Hocko wrote: > On Wed 13-10-21 16:39:38, Arnd Bergmann wrote: >> From: Arnd Bergmann >> >> The previous change added a compile time warning for the >> CONFIG_MEMORY_HOTPLUG=n case: >> >> mm/migrate.c:3216:22: error: 'migrate_on_reclaim_callback' defined but not used [-Werror=unused-function] >> 3216 | static int __meminit migrate_on_reclaim_callback(struct notifier_block *self, >> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ >> mm/migrate.c:3197:13: error: 'set_migration_target_nodes' defined but not used [-Werror=unused-function] >> 3197 | static void set_migration_target_nodes(void) >> | ^~~~~~~~~~~~~~~~~~~~~~~~~~ >> >> Rework the hotplug_memory_notifier() stub implementation into >> an inline function so it always references its argument but >> ignores it, leading the compiler to silently drop the hotplug >> memory notifier function and further code referenced from it. >> >> To do this, the #ifdef around those functions need to be removed >> as well, but this tends to help with readability and build coverage. >> >> Fixes: dd3e24b84bc1 ("mm/migrate: add CPU hotplug to demotion #ifdef") > > This is not a sha1 in the Linus tree. I suspect this comes from > linux-next and akpm patch queue. Those sha1s are not stable so it is > better to not reference them. I did not find this SHA on latest linux-next (20211015) as well. > > Can we fold that into patch directly? +1 > >> Signed-off-by: Arnd Bergmann > > The fix looks good to me. > Acked-by: Michal Hocko > Thanks! > >> --- >> include/linux/memory.h | 5 ++++- >> mm/migrate.c | 6 +----- >> mm/page_ext.c | 4 +--- >> mm/slab.c | 4 ++-- >> 4 files changed, 8 insertions(+), 11 deletions(-) >> >> diff --git a/include/linux/memory.h b/include/linux/memory.h >> index a216829df280..95af54f585a1 100644 >> --- a/include/linux/memory.h >> +++ b/include/linux/memory.h >> @@ -125,7 +125,10 @@ static inline int memory_notify(unsigned long val, void *v) >> { >> return 0; >> } >> -#define hotplug_memory_notifier(fn, pri) ({ 0; }) >> +static inline int hotplug_memory_notifier(notifier_fn_t fn, int pri) >> +{ >> + return 0; >> +} >> /* These aren't inline functions due to a GCC bug. */ >> #define register_hotmemory_notifier(nb) ({ (void)(nb); 0; }) >> #define unregister_hotmemory_notifier(nb) ({ (void)(nb); }) >> diff --git a/mm/migrate.c b/mm/migrate.c >> index 7769abac8aad..32303d517e10 100644 >> --- a/mm/migrate.c >> +++ b/mm/migrate.c >> @@ -3059,7 +3059,7 @@ void migrate_vma_finalize(struct migrate_vma *migrate) >> EXPORT_SYMBOL(migrate_vma_finalize); >> #endif /* CONFIG_DEVICE_PRIVATE */ >> >> -#if defined(CONFIG_MEMORY_HOTPLUG) || defined(CONFIG_HOTPLUG_CPU) >> +#if defined(CONFIG_HOTPLUG_CPU) >> /* Disable reclaim-based migration. */ >> static void __disable_all_migrate_targets(void) >> { >> @@ -3201,7 +3201,6 @@ static void set_migration_target_nodes(void) >> put_online_mems(); >> } >> >> -#if defined(CONFIG_MEMORY_HOTPLUG) >> /* >> * This leaves migrate-on-reclaim transiently disabled between >> * the MEM_GOING_OFFLINE and MEM_OFFLINE events. This runs >> @@ -3258,9 +3257,7 @@ static int __meminit migrate_on_reclaim_callback(struct notifier_block *self, >> >> return notifier_from_errno(0); >> } >> -#endif /* CONFIG_MEMORY_HOTPLUG */ >> >> -#ifdef CONFIG_HOTPLUG_CPU >> /* >> * React to hotplug events that might affect the migration targets >> * like events that online or offline NUMA nodes. >> @@ -3302,4 +3299,3 @@ static int __init migrate_on_reclaim_init(void) >> } >> late_initcall(migrate_on_reclaim_init); >> #endif /* CONFIG_HOTPLUG_CPU */ >> -#endif /* CONFIG_MEMORY_HOTPLUG || CONFIG_HOTPLUG_CPU */ >> diff --git a/mm/page_ext.c b/mm/page_ext.c >> index 106079e67c2e..6242afb24d84 100644 >> --- a/mm/page_ext.c >> +++ b/mm/page_ext.c >> @@ -269,7 +269,7 @@ static int __meminit init_section_page_ext(unsigned long pfn, int nid) >> total_usage += table_size; >> return 0; >> } >> -#ifdef CONFIG_MEMORY_HOTPLUG >> + >> static void free_page_ext(void *addr) >> { >> if (is_vmalloc_addr(addr)) { >> @@ -374,8 +374,6 @@ static int __meminit page_ext_callback(struct notifier_block *self, >> return notifier_from_errno(ret); >> } >> >> -#endif >> - >> void __init page_ext_init(void) >> { >> unsigned long pfn; >> diff --git a/mm/slab.c b/mm/slab.c >> index 01775fe0e002..da132a9ae6f8 100644 >> --- a/mm/slab.c >> +++ b/mm/slab.c >> @@ -1095,7 +1095,7 @@ static int slab_offline_cpu(unsigned int cpu) >> return 0; >> } >> >> -#if defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG) >> +#if defined(CONFIG_NUMA) >> /* >> * Drains freelist for a node on each slab cache, used for memory hot-remove. >> * Returns -EBUSY if all objects cannot be drained so that the node is not >> @@ -1157,7 +1157,7 @@ static int __meminit slab_memory_callback(struct notifier_block *self, >> out: >> return notifier_from_errno(ret); >> } >> -#endif /* CONFIG_NUMA && CONFIG_MEMORY_HOTPLUG */ >> +#endif /* CONFIG_NUMA */ >> >> /* >> * swap the static kmem_cache_node with kmalloced memory >> -- >> 2.29.2 >