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-rw-r--r--kernel/memremap.c34
1 files changed, 34 insertions, 0 deletions
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 066e73c2fcc9..f1d1e0dfe8b4 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -18,6 +18,8 @@
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/memory_hotplug.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
#ifndef ioremap_cache
/* temporary while we convert existing ioremap_cache users to memremap */
@@ -219,6 +221,34 @@ static unsigned long order_at(struct resource *res, unsigned long pgoff)
for (pgoff = 0, order = order_at((res), pgoff); order < ULONG_MAX; \
pgoff += 1UL << order, order = order_at((res), pgoff))
+#if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
+int 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);
+
+ /*
+ * 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 page->pgmap->page_fault(vma, addr, page, flags, pmdp);
+}
+EXPORT_SYMBOL(device_private_entry_fault);
+#endif /* CONFIG_DEVICE_PRIVATE */
+
static void pgmap_radix_release(struct resource *res)
{
unsigned long pgoff, order;
@@ -356,6 +386,10 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
}
pgmap->ref = ref;
pgmap->res = &page_map->res;
+ pgmap->type = MEMORY_DEVICE_HOST;
+ pgmap->page_fault = NULL;
+ pgmap->page_free = NULL;
+ pgmap->data = NULL;
mutex_lock(&pgmap_lock);
error = 0;