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Date: Tue, 18 Sep 2018 16:35:37 -0400
From: Jerome Glisse <jglisse@...hat.com>
To: Dan Williams <dan.j.williams@...el.com>
Cc: akpm@...ux-foundation.org, Christoph Hellwig <hch@....de>,
Logan Gunthorpe <logang@...tatee.com>,
alexander.h.duyck@...el.com, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 6/7] mm, hmm: Replace hmm_devmem_pages_create() with
devm_memremap_pages()
On Wed, Sep 12, 2018 at 07:22:33PM -0700, Dan Williams wrote:
> Commit e8d513483300 "memremap: change devm_memremap_pages interface to
> use struct dev_pagemap" refactored devm_memremap_pages() to allow a
> dev_pagemap instance to be supplied. Passing in a dev_pagemap interface
> simplifies the design of pgmap type drivers in that they can rely on
> container_of() to lookup any private data associated with the given
> dev_pagemap instance.
>
> In addition to the cleanups this also gives hmm users multi-order-radix
> improvements that arrived with commit ab1b597ee0e4 "mm,
> devm_memremap_pages: use multi-order radix for ZONE_DEVICE lookups"
>
> As part of the conversion to the devm_memremap_pages() method of
> handling the percpu_ref relative to when pages are put, the percpu_ref
> completion needs to move to hmm_devmem_ref_exit(). See commit
> 71389703839e ("mm, zone_device: Replace {get, put}_zone_device_page...")
> for details.
>
> Reviewed-by: Christoph Hellwig <hch@....de>
Reviewed-by: Jérôme Glisse <jglisse@...hat.com>
> Cc: Logan Gunthorpe <logang@...tatee.com>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> ---
> mm/hmm.c | 194 ++++++++------------------------------------------------------
> 1 file changed, 26 insertions(+), 168 deletions(-)
>
> diff --git a/mm/hmm.c b/mm/hmm.c
> index ec1d9eccf176..c6cab5205b99 100644
> --- a/mm/hmm.c
> +++ b/mm/hmm.c
> @@ -938,17 +938,16 @@ static void hmm_devmem_ref_exit(void *data)
> struct hmm_devmem *devmem;
>
> devmem = container_of(ref, struct hmm_devmem, ref);
> + wait_for_completion(&devmem->completion);
> percpu_ref_exit(ref);
> }
>
> -static void hmm_devmem_ref_kill(void *data)
> +static void hmm_devmem_ref_kill(struct percpu_ref *ref)
> {
> - struct percpu_ref *ref = data;
> struct hmm_devmem *devmem;
>
> devmem = container_of(ref, struct hmm_devmem, ref);
> percpu_ref_kill(ref);
> - wait_for_completion(&devmem->completion);
> }
>
> static int hmm_devmem_fault(struct vm_area_struct *vma,
> @@ -971,152 +970,6 @@ static void hmm_devmem_free(struct page *page, void *data)
> devmem->ops->free(devmem, page);
> }
>
> -static DEFINE_MUTEX(hmm_devmem_lock);
> -static RADIX_TREE(hmm_devmem_radix, GFP_KERNEL);
> -
> -static void hmm_devmem_radix_release(struct resource *resource)
> -{
> - resource_size_t key;
> -
> - mutex_lock(&hmm_devmem_lock);
> - for (key = resource->start;
> - key <= resource->end;
> - key += PA_SECTION_SIZE)
> - radix_tree_delete(&hmm_devmem_radix, key >> PA_SECTION_SHIFT);
> - mutex_unlock(&hmm_devmem_lock);
> -}
> -
> -static void hmm_devmem_release(void *data)
> -{
> - struct hmm_devmem *devmem = data;
> - struct resource *resource = devmem->resource;
> - unsigned long start_pfn, npages;
> - struct zone *zone;
> - struct page *page;
> -
> - /* pages are dead and unused, undo the arch mapping */
> - start_pfn = (resource->start & ~(PA_SECTION_SIZE - 1)) >> PAGE_SHIFT;
> - npages = ALIGN(resource_size(resource), PA_SECTION_SIZE) >> PAGE_SHIFT;
> -
> - page = pfn_to_page(start_pfn);
> - zone = page_zone(page);
> -
> - mem_hotplug_begin();
> - if (resource->desc == IORES_DESC_DEVICE_PRIVATE_MEMORY)
> - __remove_pages(zone, start_pfn, npages, NULL);
> - else
> - arch_remove_memory(start_pfn << PAGE_SHIFT,
> - npages << PAGE_SHIFT, NULL);
> - mem_hotplug_done();
> -
> - hmm_devmem_radix_release(resource);
> -}
> -
> -static int hmm_devmem_pages_create(struct hmm_devmem *devmem)
> -{
> - resource_size_t key, align_start, align_size, align_end;
> - struct device *device = devmem->device;
> - int ret, nid, is_ram;
> - unsigned long pfn;
> -
> - align_start = devmem->resource->start & ~(PA_SECTION_SIZE - 1);
> - align_size = ALIGN(devmem->resource->start +
> - resource_size(devmem->resource),
> - PA_SECTION_SIZE) - align_start;
> -
> - is_ram = region_intersects(align_start, align_size,
> - IORESOURCE_SYSTEM_RAM,
> - IORES_DESC_NONE);
> - if (is_ram == REGION_MIXED) {
> - WARN_ONCE(1, "%s attempted on mixed region %pr\n",
> - __func__, devmem->resource);
> - return -ENXIO;
> - }
> - if (is_ram == REGION_INTERSECTS)
> - return -ENXIO;
> -
> - if (devmem->resource->desc == IORES_DESC_DEVICE_PUBLIC_MEMORY)
> - devmem->pagemap.type = MEMORY_DEVICE_PUBLIC;
> - else
> - devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
> -
> - devmem->pagemap.res = *devmem->resource;
> - devmem->pagemap.page_fault = hmm_devmem_fault;
> - devmem->pagemap.page_free = hmm_devmem_free;
> - devmem->pagemap.dev = devmem->device;
> - devmem->pagemap.ref = &devmem->ref;
> - devmem->pagemap.data = devmem;
> -
> - mutex_lock(&hmm_devmem_lock);
> - align_end = align_start + align_size - 1;
> - for (key = align_start; key <= align_end; key += PA_SECTION_SIZE) {
> - struct hmm_devmem *dup;
> -
> - dup = radix_tree_lookup(&hmm_devmem_radix,
> - key >> PA_SECTION_SHIFT);
> - if (dup) {
> - dev_err(device, "%s: collides with mapping for %s\n",
> - __func__, dev_name(dup->device));
> - mutex_unlock(&hmm_devmem_lock);
> - ret = -EBUSY;
> - goto error;
> - }
> - ret = radix_tree_insert(&hmm_devmem_radix,
> - key >> PA_SECTION_SHIFT,
> - devmem);
> - if (ret) {
> - dev_err(device, "%s: failed: %d\n", __func__, ret);
> - mutex_unlock(&hmm_devmem_lock);
> - goto error_radix;
> - }
> - }
> - mutex_unlock(&hmm_devmem_lock);
> -
> - nid = dev_to_node(device);
> - if (nid < 0)
> - nid = numa_mem_id();
> -
> - mem_hotplug_begin();
> - /*
> - * For device private memory we call add_pages() as we only need to
> - * allocate and initialize struct page for the device memory. More-
> - * over the device memory is un-accessible thus we do not want to
> - * create a linear mapping for the memory like arch_add_memory()
> - * would do.
> - *
> - * For device public memory, which is accesible by the CPU, we do
> - * want the linear mapping and thus use arch_add_memory().
> - */
> - if (devmem->pagemap.type == MEMORY_DEVICE_PUBLIC)
> - ret = arch_add_memory(nid, align_start, align_size, NULL,
> - false);
> - else
> - ret = add_pages(nid, align_start >> PAGE_SHIFT,
> - align_size >> PAGE_SHIFT, NULL, false);
> - if (ret) {
> - mem_hotplug_done();
> - goto error_add_memory;
> - }
> - move_pfn_range_to_zone(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
> - align_start >> PAGE_SHIFT,
> - align_size >> PAGE_SHIFT, NULL);
> - mem_hotplug_done();
> -
> - for (pfn = devmem->pfn_first; pfn < devmem->pfn_last; pfn++) {
> - struct page *page = pfn_to_page(pfn);
> -
> - page->pgmap = &devmem->pagemap;
> - }
> - return 0;
> -
> -error_add_memory:
> - untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
> -error_radix:
> - hmm_devmem_radix_release(devmem->resource);
> -error:
> - return ret;
> -}
> -
> /*
> * hmm_devmem_add() - hotplug ZONE_DEVICE memory for device memory
> *
> @@ -1140,6 +993,7 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
> {
> struct hmm_devmem *devmem;
> resource_size_t addr;
> + void *result;
> int ret;
>
> dev_pagemap_get_ops();
> @@ -1194,14 +1048,18 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
> devmem->pfn_last = devmem->pfn_first +
> (resource_size(devmem->resource) >> PAGE_SHIFT);
>
> - ret = hmm_devmem_pages_create(devmem);
> - if (ret)
> - return ERR_PTR(ret);
> -
> - ret = devm_add_action_or_reset(device, hmm_devmem_release, devmem);
> - if (ret)
> - return ERR_PTR(ret);
> + devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
> + devmem->pagemap.res = *devmem->resource;
> + devmem->pagemap.page_fault = hmm_devmem_fault;
> + devmem->pagemap.page_free = hmm_devmem_free;
> + devmem->pagemap.altmap_valid = false;
> + devmem->pagemap.ref = &devmem->ref;
> + devmem->pagemap.data = devmem;
>
> + result = devm_memremap_pages(devmem->device, &devmem->pagemap,
> + hmm_devmem_ref_kill);
> + if (IS_ERR(result))
> + return result;
> return devmem;
> }
> EXPORT_SYMBOL(hmm_devmem_add);
> @@ -1211,6 +1069,7 @@ struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops,
> struct resource *res)
> {
> struct hmm_devmem *devmem;
> + void *result;
> int ret;
>
> if (res->desc != IORES_DESC_DEVICE_PUBLIC_MEMORY)
> @@ -1243,19 +1102,18 @@ struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops,
> devmem->pfn_last = devmem->pfn_first +
> (resource_size(devmem->resource) >> PAGE_SHIFT);
>
> - ret = hmm_devmem_pages_create(devmem);
> - if (ret)
> - return ERR_PTR(ret);
> -
> - ret = devm_add_action_or_reset(device, hmm_devmem_release, devmem);
> - if (ret)
> - return ERR_PTR(ret);
> -
> - ret = devm_add_action_or_reset(device, hmm_devmem_ref_kill,
> - &devmem->ref);
> - if (ret)
> - return ERR_PTR(ret);
> + devmem->pagemap.type = MEMORY_DEVICE_PUBLIC;
> + devmem->pagemap.res = *devmem->resource;
> + devmem->pagemap.page_fault = hmm_devmem_fault;
> + devmem->pagemap.page_free = hmm_devmem_free;
> + devmem->pagemap.altmap_valid = false;
> + devmem->pagemap.ref = &devmem->ref;
> + devmem->pagemap.data = devmem;
>
> + result = devm_memremap_pages(devmem->device, &devmem->pagemap,
> + hmm_devmem_ref_kill);
> + if (IS_ERR(result))
> + return result;
> return devmem;
> }
> EXPORT_SYMBOL(hmm_devmem_add_resource);
>
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