From 987717e5e016a0dd3011d3bb16546672713f94e2 Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli Date: Tue, 14 May 2019 15:40:50 -0700 Subject: mm: change mm_update_next_owner() to update mm->owner with WRITE_ONCE The RCU reader uses rcu_dereference() inside rcu_read_lock critical sections, so the writer shall use WRITE_ONCE. Just a cleanup, we still rely on gcc to emit atomic writes in other places. Link: http://lkml.kernel.org/r/20190325225636.11635-3-aarcange@redhat.com Signed-off-by: Andrea Arcangeli Reviewed-by: Andrew Morton Cc: Hugh Dickins Cc: Jann Horn Cc: Jason Gunthorpe Cc: "Kirill A . Shutemov" Cc: Michal Hocko Cc: Mike Kravetz Cc: Mike Rapoport Cc: Oleg Nesterov Cc: Peter Xu Cc: zhong jiang Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/exit.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'kernel/exit.c') diff --git a/kernel/exit.c b/kernel/exit.c index 2166c2d92ddc..8361a560cd1d 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -422,7 +422,7 @@ retry: * freed task structure. */ if (atomic_read(&mm->mm_users) <= 1) { - mm->owner = NULL; + WRITE_ONCE(mm->owner, NULL); return; } @@ -462,7 +462,7 @@ retry: * most likely racing with swapoff (try_to_unuse()) or /proc or * ptrace or page migration (get_task_mm()). Mark owner as NULL. */ - mm->owner = NULL; + WRITE_ONCE(mm->owner, NULL); return; assign_new_owner: @@ -483,7 +483,7 @@ assign_new_owner: put_task_struct(c); goto retry; } - mm->owner = c; + WRITE_ONCE(mm->owner, c); task_unlock(c); put_task_struct(c); } -- cgit v1.2.3-59-g8ed1b