Re: [PATCH 1/9] migrate: add migrate_entry_wait_huge()

From: Simon Jeons
Date: Wed Mar 20 2013 - 19:37:07 EST

Hi Naoya,
On 03/21/2013 05:53 AM, Naoya Horiguchi wrote:
> On Wed, Mar 20, 2013 at 07:57:32AM +0800, Simon Jeons wrote:
>> Hi Naoya,
>> On 02/22/2013 03:41 AM, Naoya Horiguchi wrote:
>>> When we have a page fault for the address which is backed by a hugepage
>>> under migration, the kernel can't wait correctly until the migration
>>> finishes. This is because pte_offset_map_lock() can't get a correct
>> It seems that current hugetlb_fault still wait hugetlb page under
>> migration, how can it work without lock 2MB memory?
> Hugetlb_fault() does call migration_entry_wait(), but returns immediately.

Could you point out to me which code in function migration_entry_wait()
lead to return immediately?

> So page fault happens over and over again until the migration completes.
> IOW, migration_entry_wait() is now broken for hugepage and doesn't work
> as expected.
> Thanks,
> Naoya

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