Fix clear_refs_write() use of struct mm_walk

Don't use a static entry, so as to prevent races during concurrent use
of this function.

Reported-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index ab8ccc9d14ff..05053d701ac5 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -476,10 +476,10 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
                 return -ESRCH;
         mm = get_task_mm(task);
         if (mm) {
-                static struct mm_walk clear_refs_walk;
-                memset(&clear_refs_walk, 0, sizeof(clear_refs_walk));
-                clear_refs_walk.pmd_entry = clear_refs_pte_range;
-                clear_refs_walk.mm = mm;
+                struct mm_walk clear_refs_walk = {
+                        .pmd_entry = clear_refs_pte_range,
+                        .mm = mm,
+                };
                 down_read(&mm->mmap_sem);
                 for (vma = mm->mmap; vma; vma = vma->vm_next) {
                         clear_refs_walk.private = vma;