diff options
| author |   Andrea Arcangeli <aarcange@redhat.com> | 2019-05-14 15:40:50 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2019-05-14 19:52:47 -0700 |
| commit | 987717e5e016a0dd3011d3bb16546672713f94e2 (patch) | |
| tree | fa83028052001ed851507f8a42b241ba45212b20 /kernel/exit.c | |
| parent | userfaultfd: use RCU to free the task struct when fork fails (diff) | |
| download | linux-dev-987717e5e016a0dd3011d3bb16546672713f94e2.tar.xz linux-dev-987717e5e016a0dd3011d3bb16546672713f94e2.zip | |
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 <aarcange@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: zhong jiang <zhongjiang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/exit.c')
| -rw-r--r-- | kernel/exit.c | 6 |
1 files changed, 3 insertions, 3 deletions
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); } |