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[91.12.105.78]) by smtp.gmail.com with ESMTPSA id r9sm1554409wrn.95.2021.10.14.00.08.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 14 Oct 2021 00:08:51 -0700 (PDT) Message-ID: <11ca4abc-efb7-6304-df36-98951915b2e3@redhat.com> Date: Thu, 14 Oct 2021 09:08:50 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.0 Subject: Re: [PATCH] mm/migrate: rework hotplug_memory_notifier() stub Content-Language: en-US To: Arnd Bergmann , Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Dave Hansen , Stephen Rothwell Cc: Arnd Bergmann , Michal Hocko , Oscar Salvador , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20211013144029.2154629-1-arnd@kernel.org> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20211013144029.2154629-1-arnd@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 13.10.21 16:39, 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") > Signed-off-by: Arnd Bergmann > --- > 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 > Acked-by: David Hildenbrand -- Thanks, David / dhildenb