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Subject[PATCH v4 6/8] mm, hmm: Replace hmm_devmem_pages_create() with devm_memremap_pages()
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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@lst.de>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
mm/hmm.c | 197 ++++++++------------------------------------------------------
1 file changed, 26 insertions(+), 171 deletions(-)

diff --git a/mm/hmm.c b/mm/hmm.c
index d65a9419dbc2..c5a6e61ee302 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -933,17 +933,16 @@ 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,
@@ -964,155 +963,6 @@ 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, align_start, align_size;
-
- align_start = resource->start & ~(PA_SECTION_SIZE - 1);
- align_size = ALIGN(resource_size(resource), PA_SECTION_SIZE);
-
- 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
*
@@ -1136,6 +986,7 @@ 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();
@@ -1190,14 +1041,18 @@ 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);
@@ -1207,6 +1062,7 @@ 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)
@@ -1239,19 +1095,18 @@ 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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