[PATCH mm-unstable v1 1/4] mm/gup_test: fix PIN_LONGTERM_TEST_READ with highmem

David Hildenbrand
2022-12-05T19:41:34Z

... we have to kmap()/kunmap(), otherwise this won't work as expected
with highmem.

Fixes: c77369b437f9 ("mm/gup_test: start/stop/read functionality for PIN LONGTERM test")
Signed-off-by: David Hildenbrand <david@redhat.com>
---
mm/gup_test.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/mm/gup_test.c b/mm/gup_test.c
index 0d76d9b4bb5a..33f431e0da60 100644
--- a/mm/gup_test.c
+++ b/mm/gup_test.c
@@ -4,6 +4,7 @@
#include <linux/uaccess.h>
#include <linux/ktime.h>
#include <linux/debugfs.h>
+#include <linux/highmem.h>
#include "gup_test.h"

static void put_back_pages(unsigned int cmd, struct page **pages,
@@ -297,10 +298,13 @@ static inline int pin_longterm_test_read(unsigned long arg)
return -EFAULT;

for (i = 0; i < pin_longterm_test_nr_pages; i++) {
- void *addr = page_to_virt(pin_longterm_test_pages[i]);
+ void *addr = kmap_local_page(pin_longterm_test_pages[i]);
+ unsigned long ret;

- if (copy_to_user((void __user *)(unsigned long)user_addr, addr,
- PAGE_SIZE))
+ ret = copy_to_user((void __user *)(unsigned long)user_addr, addr,
+ PAGE_SIZE);
+ kunmap_local(addr);
+ if (ret)
return -EFAULT;
user_addr += PAGE_SIZE;
}
--
2.38.1