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From:   "Wang, Haiyue" <haiyue.wang@intel.com>
To:     "Huang, Ying" <ying.huang@intel.com>
CC:     "linux-mm@kvack.org" <linux-mm@kvack.org>,
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Subject: RE: [PATCH v3 1/2] mm: migration: fix the FOLL_GET failure on
 following huge page
Thread-Topic: [PATCH v3 1/2] mm: migration: fix the FOLL_GET failure on
 following huge page
Thread-Index: AQHYsELdwe4rYEhX3kmQ25LUIwgSE62vNNY6gAAAhrA=
Date:   Mon, 15 Aug 2022 02:10:59 +0000
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> -----Original Message-----
> From: Huang, Ying <ying.huang@intel.com>
> Sent: Monday, August 15, 2022 09:59
> To: Wang, Haiyue <haiyue.wang@intel.com>
> Cc: linux-mm@kvack.org; linux-kernel@vger.kernel.org; akpm@linux-foundati=
on.org; david@redhat.com;
> linmiaohe@huawei.com; songmuchun@bytedance.com; naoya.horiguchi@linux.dev=
; alex.sierra@amd.com
> Subject: Re: [PATCH v3 1/2] mm: migration: fix the FOLL_GET failure on fo=
llowing huge page
>=20
> Haiyue Wang <haiyue.wang@intel.com> writes:
>=20
> > Not all huge page APIs support FOLL_GET option, so the __NR_move_pages
>=20
> move_pages() is a syscall, so you can just call it move_pages(), or
> move_pages() syscall.

The application meets the issue, use the bellow function:
syscall (__NR_move_pages, 0, n_pages, ptr, 0, status, 0)

So I used it directly in the commit. "move_pages() syscall" is better.
Will update latter.

>=20
> > will fail to get the page node information for huge page.
>                                                  ~~~~~~~~~
> some huge pages?

OK.

>=20
> > This is an temporary solution to mitigate the racing fix.
>=20
> Why is it "racing fix"?  This isn't a race condition fix.

The 'Fixes' commit is about race condition fix.

How about " his is an temporary solution to mitigate the side effect
Of the race condition fix"

>=20
> Best Regards,
> Huang, Ying
>=20
> > After supporting follow huge page by FOLL_GET is done, this fix can be
> > reverted safely.
> >
> > Fixes: 4cd614841c06 ("mm: migration: fix possible do_pages_stat_array r=
acing with memory offline")
> > Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
>=20
> [snip]