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authorBen Hutchings <ben@decadent.org.uk>2012-07-31 16:45:02 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-06-11 12:04:17 -0700
commit7e4d02fdb2bb0f47405a0961a7f3991a56b5981b (patch)
tree5daed7ed40bcc14e59a6ec0e19d88fcd087ffd19
parent984ca88a55ccf51d4eeef67ce2247c58694a2dc5 (diff)
downloadlinux-linaro-stable-7e4d02fdb2bb0f47405a0961a7f3991a56b5981b.tar.gz
mm: add kmap_to_page()
commit fcb8996728fb59eddf84678df7cb213b2c9a2e26 upstream. This is extracted from Mel Gorman's commit 5a178119b0fb ('mm: add support for direct_IO to highmem pages') upstream. Required to backport commit b9cdc88df8e6 ('virtio: 9p: correctly pass physical address to userspace for high pages'). Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Cc: Yijing Wang <wangyijing@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--include/linux/highmem.h7
-rw-r--r--mm/highmem.c12
2 files changed, 19 insertions, 0 deletions
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index d3999b4e26cc..e186e3c28ed8 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -39,10 +39,17 @@ extern unsigned long totalhigh_pages;
void kmap_flush_unused(void);
+struct page *kmap_to_page(void *addr);
+
#else /* CONFIG_HIGHMEM */
static inline unsigned int nr_free_highpages(void) { return 0; }
+static inline struct page *kmap_to_page(void *addr)
+{
+ return virt_to_page(addr);
+}
+
#define totalhigh_pages 0UL
#ifndef ARCH_HAS_KMAP
diff --git a/mm/highmem.c b/mm/highmem.c
index 57d82c6250c3..d517cd16a6eb 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -94,6 +94,18 @@ static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
do { spin_unlock(&kmap_lock); (void)(flags); } while (0)
#endif
+struct page *kmap_to_page(void *vaddr)
+{
+ unsigned long addr = (unsigned long)vaddr;
+
+ if (addr >= PKMAP_ADDR(0) && addr <= PKMAP_ADDR(LAST_PKMAP)) {
+ int i = (addr - PKMAP_ADDR(0)) >> PAGE_SHIFT;
+ return pte_page(pkmap_page_table[i]);
+ }
+
+ return virt_to_page(addr);
+}
+
static void flush_all_zero_pkmaps(void)
{
int i;