Re: [RFC PATCH 13/15] mm: convert MAX_ORDER sized static arrays to dynamic ones.

["Christian König" <christian.koenig@amd.com>]

Am 05.08.21 um 21:02 schrieb Zi Yan:
> From: Zi Yan <ziy@nvidia.com>
>
> This prepares for the upcoming changes to make MAX_ORDER a boot time
> parameter instead of compilation time constant. All static arrays with
> MAX_ORDER size are converted to pointers and their memory is allocated
> at runtime.

Well in general I strongly suggest to not use the patter 
kmalloc(sizeof(some struct) * MAX_ORDER,...) instead use kmalloc_array, 
kcalloc etc..

Then when a array is embedded at the end of a structure you can use a 
trailing array and the struct_size() macro to determine the allocation size.

Additional to that separating the patch into changes for TTM to make the 
maximum allocation order independent from MAX_ORDER would be rather good 
to have I think.

Regards,
Christian.

>
> free_area array in struct zone is allocated using memblock_alloc_node()
> at boot time and using kzalloc() when memory is hot-added.
>
> MAX_ORDER in arm64 nVHE code is independent of kernel buddy allocator,
> so use CONFIG_FORCE_MAX_ZONEORDER instead.
>
> Signed-off-by: Zi Yan <ziy@nvidia.com>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: Christian Koenig <christian.koenig@amd.com>
> Cc: David Airlie <airlied@linux.ie>
> Cc: kexec@lists.infradead.org
> Cc: linux-doc@vger.kernel.org
> Cc: dri-devel@lists.freedesktop.org
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org
> ---
>   .../admin-guide/kdump/vmcoreinfo.rst          |  2 +-
>   drivers/gpu/drm/ttm/ttm_device.c              |  7 ++-
>   drivers/gpu/drm/ttm/ttm_pool.c                | 58 +++++++++++++++++--
>   include/drm/ttm/ttm_pool.h                    |  4 +-
>   include/linux/memory_hotplug.h                |  1 +
>   include/linux/mmzone.h                        |  2 +-
>   mm/memory_hotplug.c                           |  1 +
>   mm/page_alloc.c                               | 48 ++++++++++++---
>   8 files changed, 104 insertions(+), 19 deletions(-)
>
> diff --git a/Documentation/admin-guide/kdump/vmcoreinfo.rst b/Documentation/admin-guide/kdump/vmcoreinfo.rst
> index 3861a25faae1..1c9449b9458f 100644
> --- a/Documentation/admin-guide/kdump/vmcoreinfo.rst
> +++ b/Documentation/admin-guide/kdump/vmcoreinfo.rst
> @@ -172,7 +172,7 @@ variables.
>   Offset of the free_list's member. This value is used to compute the number
>   of free pages.
>   
> -Each zone has a free_area structure array called free_area[MAX_ORDER].
> +Each zone has a free_area structure array called free_area with length of MAX_ORDER.
>   The free_list represents a linked list of free page blocks.
>   
>   (list_head, next|prev)
> diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c
> index 74e3b460132b..7d994c03fbd0 100644
> --- a/drivers/gpu/drm/ttm/ttm_device.c
> +++ b/drivers/gpu/drm/ttm/ttm_device.c
> @@ -94,7 +94,9 @@ static int ttm_global_init(void)
>   		>> PAGE_SHIFT;
>   	num_dma32 = min(num_dma32, 2UL << (30 - PAGE_SHIFT));
>   
> -	ttm_pool_mgr_init(num_pages);
> +	ret = ttm_pool_mgr_init(num_pages);
> +	if (ret)
> +		goto out;
>   	ttm_tt_mgr_init(num_pages, num_dma32);
>   
>   	glob->dummy_read_page = alloc_page(__GFP_ZERO | GFP_DMA32);
> @@ -216,7 +218,8 @@ int ttm_device_init(struct ttm_device *bdev, struct ttm_device_funcs *funcs,
>   	bdev->funcs = funcs;
>   
>   	ttm_sys_man_init(bdev);
> -	ttm_pool_init(&bdev->pool, dev, use_dma_alloc, use_dma32);
> +	if (ttm_pool_init(&bdev->pool, dev, use_dma_alloc, use_dma32))
> +		return -ENOMEM;
>   
>   	bdev->vma_manager = vma_manager;
>   	INIT_DELAYED_WORK(&bdev->wq, ttm_device_delayed_workqueue);
> diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c
> index cb38b1a17b09..ae20c80f14a4 100644
> --- a/drivers/gpu/drm/ttm/ttm_pool.c
> +++ b/drivers/gpu/drm/ttm/ttm_pool.c
> @@ -64,11 +64,11 @@ module_param(page_pool_size, ulong, 0644);
>   
>   static atomic_long_t allocated_pages;
>   
> -static struct ttm_pool_type global_write_combined[MAX_ORDER];
> -static struct ttm_pool_type global_uncached[MAX_ORDER];
> +static struct ttm_pool_type *global_write_combined;
> +static struct ttm_pool_type *global_uncached;
>   
> -static struct ttm_pool_type global_dma32_write_combined[MAX_ORDER];
> -static struct ttm_pool_type global_dma32_uncached[MAX_ORDER];
> +static struct ttm_pool_type *global_dma32_write_combined;
> +static struct ttm_pool_type *global_dma32_uncached;
>   
>   static struct mutex shrinker_lock;
>   static struct list_head shrinker_list;
> @@ -493,8 +493,10 @@ EXPORT_SYMBOL(ttm_pool_free);
>    * @use_dma32: true if GFP_DMA32 should be used
>    *
>    * Initialize the pool and its pool types.
> + *
> + * Returns: 0 on successe, negative error code otherwise
>    */
> -void ttm_pool_init(struct ttm_pool *pool, struct device *dev,
> +int ttm_pool_init(struct ttm_pool *pool, struct device *dev,
>   		   bool use_dma_alloc, bool use_dma32)
>   {
>   	unsigned int i, j;
> @@ -506,11 +508,30 @@ void ttm_pool_init(struct ttm_pool *pool, struct device *dev,
>   	pool->use_dma32 = use_dma32;
>   
>   	if (use_dma_alloc) {
> -		for (i = 0; i < TTM_NUM_CACHING_TYPES; ++i)
> +		for (i = 0; i < TTM_NUM_CACHING_TYPES; ++i) {
> +			pool->caching[i].orders =
> +				kzalloc(sizeof(struct ttm_pool_type) * MAX_ORDER,
> +					GFP_KERNEL);
> +			if (!pool->caching[i].orders) {
> +				i--;
> +				goto failed;
> +			}
>   			for (j = 0; j < MAX_ORDER; ++j)
>   				ttm_pool_type_init(&pool->caching[i].orders[j],
>   						   pool, i, j);
> +
> +		}
> +		return 0;
> +
> +failed:
> +		for (; i >= 0; i--) {
> +			for (j = 0; j < MAX_ORDER; ++j)
> +				ttm_pool_type_fini(&pool->caching[i].orders[j]);
> +			kfree(pool->caching[i].orders);
> +		}
> +		return -ENOMEM;
>   	}
> +	return 0;
>   }
>   
>   /**
> @@ -696,6 +717,31 @@ int ttm_pool_mgr_init(unsigned long num_pages)
>   	mutex_init(&shrinker_lock);
>   	INIT_LIST_HEAD(&shrinker_list);
>   
> +	if (!global_write_combined) {
> +		global_write_combined = kzalloc(sizeof(struct ttm_pool_type) * MAX_ORDER,
> +						GFP_KERNEL);
> +		if (!global_write_combined)
> +			return -ENOMEM;
> +	}
> +	if (!global_uncached) {
> +		global_uncached = kzalloc(sizeof(struct ttm_pool_type) * MAX_ORDER,
> +					  GFP_KERNEL);
> +		if (!global_uncached)
> +			return -ENOMEM;
> +	}
> +	if (!global_dma32_write_combined) {
> +		global_dma32_write_combined = kzalloc(sizeof(struct ttm_pool_type) * MAX_ORDER,
> +						      GFP_KERNEL);
> +		if (!global_dma32_write_combined)
> +			return -ENOMEM;
> +	}
> +	if (!global_dma32_uncached) {
> +		global_dma32_uncached = kzalloc(sizeof(struct ttm_pool_type) * MAX_ORDER,
> +						GFP_KERNEL);
> +		if (!global_dma32_uncached)
> +			return -ENOMEM;
> +	}
> +
>   	for (i = 0; i < MAX_ORDER; ++i) {
>   		ttm_pool_type_init(&global_write_combined[i], NULL,
>   				   ttm_write_combined, i);
> diff --git a/include/drm/ttm/ttm_pool.h b/include/drm/ttm/ttm_pool.h
> index 4321728bdd11..5c09e3cf63ce 100644
> --- a/include/drm/ttm/ttm_pool.h
> +++ b/include/drm/ttm/ttm_pool.h
> @@ -71,7 +71,7 @@ struct ttm_pool {
>   	bool use_dma32;
>   
>   	struct {
> -		struct ttm_pool_type orders[MAX_ORDER];
> +		struct ttm_pool_type *orders;
>   	} caching[TTM_NUM_CACHING_TYPES];
>   };
>   
> @@ -79,7 +79,7 @@ int ttm_pool_alloc(struct ttm_pool *pool, struct ttm_tt *tt,
>   		   struct ttm_operation_ctx *ctx);
>   void ttm_pool_free(struct ttm_pool *pool, struct ttm_tt *tt);
>   
> -void ttm_pool_init(struct ttm_pool *pool, struct device *dev,
> +int ttm_pool_init(struct ttm_pool *pool, struct device *dev,
>   		   bool use_dma_alloc, bool use_dma32);
>   void ttm_pool_fini(struct ttm_pool *pool);
>   
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index 97f874a60607..c16aa66db61e 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -326,6 +326,7 @@ extern void clear_zone_contiguous(struct zone *zone);
>   
>   #ifdef CONFIG_MEMORY_HOTPLUG
>   extern void __ref free_area_init_core_hotplug(int nid);
> +extern void __ref free_area_deinit_core_hotplug(int nid);
>   extern int __add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags);
>   extern int add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags);
>   extern int add_memory_resource(int nid, struct resource *resource,
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 322b995942e5..09aafc05aef4 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -609,7 +609,7 @@ struct zone {
>   	ZONE_PADDING(_pad1_)
>   
>   	/* free areas of different sizes */
> -	struct free_area	free_area[MAX_ORDER];
> +	struct free_area	*free_area;
>   
>   	/* zone flags, see below */
>   	unsigned long		flags;
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 91ca751ac20c..4ce20b6482aa 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1239,6 +1239,7 @@ static void rollback_node_hotadd(int nid)
>   
>   	arch_refresh_nodedata(nid, NULL);
>   	free_percpu(pgdat->per_cpu_nodestats);
> +	free_area_deinit_core_hotplug(nid);
>   	arch_free_nodedata(pgdat);
>   }
>   
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index e4657009fd4f..bfa6962f7615 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -6053,11 +6053,21 @@ void show_free_areas(unsigned int filter, nodemask_t *nodemask)
>   
>   	for_each_populated_zone(zone) {
>   		unsigned int order;
> -		unsigned long nr[MAX_ORDER], flags, total = 0;
> -		unsigned char types[MAX_ORDER];
> +		unsigned long *nr, flags, total = 0;
> +		unsigned char *types;
>   
>   		if (show_mem_node_skip(filter, zone_to_nid(zone), nodemask))
>   			continue;
> +
> +		nr = kmalloc(sizeof(unsigned long) * MAX_ORDER, GFP_KERNEL);
> +		if (!nr)
> +			goto skip_zone;
> +		types = kmalloc(sizeof(unsigned char) * MAX_ORDER, GFP_KERNEL);
> +		if (!types) {
> +			kfree(nr);
> +			goto skip_zone;
> +		}
> +
>   		show_node(zone);
>   		printk(KERN_CONT "%s: ", zone->name);
>   
> @@ -6083,8 +6093,11 @@ void show_free_areas(unsigned int filter, nodemask_t *nodemask)
>   				show_migration_types(types[order]);
>   		}
>   		printk(KERN_CONT "= %lukB\n", K(total));
> -	}
>   
> +		kfree(nr);
> +		kfree(types);
> +	}
> +skip_zone:
>   	hugetlb_show_meminfo();
>   
>   	printk("%ld total pagecache pages\n", global_node_page_state(NR_FILE_PAGES));
> @@ -7429,8 +7442,8 @@ static void __meminit pgdat_init_internals(struct pglist_data *pgdat)
>   	lruvec_init(&pgdat->__lruvec);
>   }
>   
> -static void __meminit zone_init_internals(struct zone *zone, enum zone_type idx, int nid,
> -							unsigned long remaining_pages)
> +static void __init zone_init_internals(struct zone *zone, enum zone_type idx, int nid,
> +							unsigned long remaining_pages, bool hotplug)
>   {
>   	atomic_long_set(&zone->managed_pages, remaining_pages);
>   	zone_set_nid(zone, nid);
> @@ -7439,6 +7452,16 @@ static void __meminit zone_init_internals(struct zone *zone, enum zone_type idx,
>   	spin_lock_init(&zone->lock);
>   	zone_seqlock_init(zone);
>   	zone_pcp_init(zone);
> +	if (hotplug)
> +		zone->free_area =
> +			kzalloc_node(sizeof(struct free_area) * MAX_ORDER,
> +				     GFP_KERNEL, nid);
> +	else
> +		zone->free_area =
> +			memblock_alloc_node(sizeof(struct free_area) * MAX_ORDER,
> +					    sizeof(struct free_area), nid);
> +	BUG_ON(!zone->free_area);
> +
>   }
>   
>   /*
> @@ -7456,7 +7479,18 @@ void __ref free_area_init_core_hotplug(int nid)
>   
>   	pgdat_init_internals(pgdat);
>   	for (z = 0; z < MAX_NR_ZONES; z++)
> -		zone_init_internals(&pgdat->node_zones[z], z, nid, 0);
> +		zone_init_internals(&pgdat->node_zones[z], z, nid, 0, true);
> +}
> +
> +void __ref free_area_deinit_core_hotplug(int nid)
> +{
> +	enum zone_type z;
> +	pg_data_t *pgdat = NODE_DATA(nid);
> +
> +	for (z = 0; z < MAX_NR_ZONES; z++) {
> +		kfree(pgdat->node_zones[z].free_area);
> +		pgdat->node_zones[z].free_area = NULL;
> +	}
>   }
>   #endif
>   
> @@ -7519,7 +7553,7 @@ static void __init free_area_init_core(struct pglist_data *pgdat)
>   		 * when the bootmem allocator frees pages into the buddy system.
>   		 * And all highmem pages will be managed by the buddy system.
>   		 */
> -		zone_init_internals(zone, j, nid, freesize);
> +		zone_init_internals(zone, j, nid, freesize, false);
>   
>   		if (!size)
>   			continue;