ascend inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4EUVI
CVE: NA

-------------------------------------------------

We encounter a call trace as follows:

[  243.545984] Call trace:
[  243.545984]  find_vma+0x90/0xa0
[  243.545985]  find_extend_vma+0x2c/0xd0
[  243.545985]  __get_user_pages+0x94/0x378
[  243.545985]  get_dump_page+0x50/0x80
[  243.545986]  elf_core_dump+0x560/0x8d8
[  243.545986]  do_coredump+0x508/0xe40
[  243.545986]  get_signal+0x130/0x788
[  243.545987]  do_signal+0x1d4/0x290
[  243.545987]  do_notify_resume+0x150/0x1c0
[  243.545988]  work_pending+0x8/0x10

elf_core_dump() doesn't hold mmap_sem because the other threads in the
same thread group are killed and blocked in exit_mm(), waiting for
calling coredump_finish().

However, share pool operations can modify the mm of any process in the
same share group and lead to concurrent problems when coredump happens.

Solution: in share pool operations, check whether coredump happened with
mm->core_state.
Signed-off-by: NTang Yizhou <tangyizhou@huawei.com>
Reviewed-by: NKefeng  Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>