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Message-Id: <20190626122724.13313-13-hch@lst.de>
Date: Wed, 26 Jun 2019 14:27:11 +0200
From: Christoph Hellwig <hch@....de>
To: Dan Williams <dan.j.williams@...el.com>,
Jérôme Glisse <jglisse@...hat.com>,
Jason Gunthorpe <jgg@...lanox.com>,
Ben Skeggs <bskeggs@...hat.com>
Cc: linux-mm@...ck.org, nouveau@...ts.freedesktop.org,
dri-devel@...ts.freedesktop.org, linux-nvdimm@...ts.01.org,
linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
Ralph Campbell <rcampbell@...dia.com>
Subject: [PATCH 12/25] memremap: add a migrate_to_ram method to struct dev_pagemap_ops
This replaces the hacky ->fault callback, which is currently directly
called from common code through a hmm specific data structure as an
exercise in layering violations.
Signed-off-by: Christoph Hellwig <hch@....de>
Reviewed-by: Ralph Campbell <rcampbell@...dia.com>
---
include/linux/hmm.h | 6 ------
include/linux/memremap.h | 6 ++++++
include/linux/swapops.h | 15 ---------------
kernel/memremap.c | 35 ++++-------------------------------
mm/hmm.c | 13 +++++--------
mm/memory.c | 9 ++-------
6 files changed, 17 insertions(+), 67 deletions(-)
diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index 44a5ac738bb5..ba19c19e24ed 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -692,11 +692,6 @@ struct hmm_devmem_ops {
* chunk, as an optimization. It must, however, prioritize the faulting address
* over all the others.
*/
-typedef vm_fault_t (*dev_page_fault_t)(struct vm_area_struct *vma,
- unsigned long addr,
- const struct page *page,
- unsigned int flags,
- pmd_t *pmdp);
struct hmm_devmem {
struct completion completion;
@@ -707,7 +702,6 @@ struct hmm_devmem {
struct dev_pagemap pagemap;
const struct hmm_devmem_ops *ops;
struct percpu_ref ref;
- dev_page_fault_t page_fault;
};
/*
diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index b8666a0d8665..ac985bd03a7f 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -80,6 +80,12 @@ struct dev_pagemap_ops {
* Wait for refcount in struct dev_pagemap to be idle and reap it.
*/
void (*cleanup)(struct dev_pagemap *pgmap);
+
+ /*
+ * Used for private (un-addressable) device memory only. Must migrate
+ * the page back to a CPU accessible page.
+ */
+ vm_fault_t (*migrate_to_ram)(struct vm_fault *vmf);
};
/**
diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 4d961668e5fc..15bdb6fe71e5 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -129,12 +129,6 @@ static inline struct page *device_private_entry_to_page(swp_entry_t entry)
{
return pfn_to_page(swp_offset(entry));
}
-
-vm_fault_t device_private_entry_fault(struct vm_area_struct *vma,
- unsigned long addr,
- swp_entry_t entry,
- unsigned int flags,
- pmd_t *pmdp);
#else /* CONFIG_DEVICE_PRIVATE */
static inline swp_entry_t make_device_private_entry(struct page *page, bool write)
{
@@ -164,15 +158,6 @@ static inline struct page *device_private_entry_to_page(swp_entry_t entry)
{
return NULL;
}
-
-static inline vm_fault_t device_private_entry_fault(struct vm_area_struct *vma,
- unsigned long addr,
- swp_entry_t entry,
- unsigned int flags,
- pmd_t *pmdp)
-{
- return VM_FAULT_SIGBUS;
-}
#endif /* CONFIG_DEVICE_PRIVATE */
#ifdef CONFIG_MIGRATION
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 3219a4c91d07..c06a5487dda7 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -11,7 +11,6 @@
#include <linux/types.h>
#include <linux/wait_bit.h>
#include <linux/xarray.h>
-#include <linux/hmm.h>
static DEFINE_XARRAY(pgmap_array);
#define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1)
@@ -46,36 +45,6 @@ static int devmap_managed_enable_get(struct device *dev, struct dev_pagemap *pgm
}
#endif /* CONFIG_DEV_PAGEMAP_OPS */
-#if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
-vm_fault_t device_private_entry_fault(struct vm_area_struct *vma,
- unsigned long addr,
- swp_entry_t entry,
- unsigned int flags,
- pmd_t *pmdp)
-{
- struct page *page = device_private_entry_to_page(entry);
- struct hmm_devmem *devmem;
-
- devmem = container_of(page->pgmap, typeof(*devmem), pagemap);
-
- /*
- * The page_fault() callback must migrate page back to system memory
- * so that CPU can access it. This might fail for various reasons
- * (device issue, device was unsafely unplugged, ...). When such
- * error conditions happen, the callback must return VM_FAULT_SIGBUS.
- *
- * Note that because memory cgroup charges are accounted to the device
- * memory, this should never fail because of memory restrictions (but
- * allocation of regular system page might still fail because we are
- * out of memory).
- *
- * There is a more in-depth description of what that callback can and
- * cannot do, in include/linux/memremap.h
- */
- return devmem->page_fault(vma, addr, page, flags, pmdp);
-}
-#endif /* CONFIG_DEVICE_PRIVATE */
-
static void pgmap_array_delete(struct resource *res)
{
xa_store_range(&pgmap_array, PHYS_PFN(res->start), PHYS_PFN(res->end),
@@ -193,6 +162,10 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
WARN(1, "Device private memory not supported\n");
return ERR_PTR(-EINVAL);
}
+ if (!pgmap->ops || !pgmap->ops->migrate_to_ram) {
+ WARN(1, "Missing migrate_to_ram method\n");
+ return ERR_PTR(-EINVAL);
+ }
break;
case MEMORY_DEVICE_FS_DAX:
if (!IS_ENABLED(CONFIG_ZONE_DEVICE) ||
diff --git a/mm/hmm.c b/mm/hmm.c
index 5b0bd5f6a74f..96633ee066d8 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -1366,15 +1366,12 @@ static void hmm_devmem_ref_kill(struct dev_pagemap *pgmap)
percpu_ref_kill(pgmap->ref);
}
-static vm_fault_t hmm_devmem_fault(struct vm_area_struct *vma,
- unsigned long addr,
- const struct page *page,
- unsigned int flags,
- pmd_t *pmdp)
+static vm_fault_t hmm_devmem_migrate_to_ram(struct vm_fault *vmf)
{
- struct hmm_devmem *devmem = page->pgmap->data;
+ struct hmm_devmem *devmem = vmf->page->pgmap->data;
- return devmem->ops->fault(devmem, vma, addr, page, flags, pmdp);
+ return devmem->ops->fault(devmem, vmf->vma, vmf->address, vmf->page,
+ vmf->flags, vmf->pmd);
}
static void hmm_devmem_free(struct page *page, void *data)
@@ -1388,6 +1385,7 @@ static const struct dev_pagemap_ops hmm_pagemap_ops = {
.page_free = hmm_devmem_free,
.kill = hmm_devmem_ref_kill,
.cleanup = hmm_devmem_ref_exit,
+ .migrate_to_ram = hmm_devmem_migrate_to_ram,
};
/*
@@ -1438,7 +1436,6 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT;
devmem->pfn_last = devmem->pfn_first +
(resource_size(devmem->resource) >> PAGE_SHIFT);
- devmem->page_fault = hmm_devmem_fault;
devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
devmem->pagemap.res = *devmem->resource;
diff --git a/mm/memory.c b/mm/memory.c
index bd21e7063bf0..293d2936fd6c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2748,13 +2748,8 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
migration_entry_wait(vma->vm_mm, vmf->pmd,
vmf->address);
} else if (is_device_private_entry(entry)) {
- /*
- * For un-addressable device memory we call the pgmap
- * fault handler callback. The callback must migrate
- * the page back to some CPU accessible page.
- */
- ret = device_private_entry_fault(vma, vmf->address, entry,
- vmf->flags, vmf->pmd);
+ vmf->page = device_private_entry_to_page(entry);
+ ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
} else if (is_hwpoison_entry(entry)) {
ret = VM_FAULT_HWPOISON;
} else {
--
2.20.1
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