Alibaba Cloud Linux 2.1903 Hotfix Security Advisory: HOTFIX-BA-2021:0013

Issued: 2021-07-21
Updated: 2021-07-21

kernel-hotfix bugfix update

We notice that hung task happens in a conner but practical scenario when
CONFIG_PREEMPT_NONE is enabled,

Where migration_entry_wait(tail) is occurred in kernel space, e.g.,
copy_to_user, which will immediately fault again without rescheduling,
and thus occupy the cpu fully.

When there are too many processes performing migration_entry_wait on
tail page, remap_page will never be done after cond_resched.

This relaxes migration_entry_wait on tail page, thus gives remap_page
a chance to complete