tree ba45b820c900f3bd2f93a37d78bb77be3f93a106
parent 47da29763ec9a153b9b685bff9db659e4e09e494
author Johannes Berg <johannes.berg@intel.com> 1610572083 +0100
committer Richard Weinberger <richard@nod.at> 1613161924 +0100

um: defer killing userspace on page table update failures

In some cases we can get to fix_range_common() with mmap_sem held,
and in others we get there without it being held. For example, we
get there with it held from sys_mprotect(), and without it held
from fork_handler().

Avoid any issues in this and simply defer killing the task until
it runs the next time. Do it on the mm so that another task that
shares the same mm can't continue running afterwards.

Cc: stable@vger.kernel.org
Fixes: 468f65976a8d ("um: Fix hung task in fix_range_common()")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>