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Wed, 23 Sep 2020 07:40:21 +0000 From: =?iso-2022-jp?B?SE9SSUdVQ0hJIE5BT1lBKBskQktZOH0hIUQ+TGkbKEIp?= To: Oscar Salvador CC: "akpm@linux-foundation.org" , "aris@ruivo.org" , "mhocko@kernel.org" , "tony.luck@intel.com" , "cai@lca.pw" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" Subject: Re: [PATCH v7 14/14] mm,hwpoison: Try to narrow window race for free pages Thread-Topic: [PATCH v7 14/14] mm,hwpoison: Try to narrow window race for free pages Thread-Index: AQHWkOhI+VqEs7V6tkit9AfJcUADzql118IA Date: Wed, 23 Sep 2020 07:40:21 +0000 Message-ID: <20200923074020.GE15221@hori.linux.bs1.fc.nec.co.jp> References: <20200922135650.1634-1-osalvador@suse.de> <20200922135650.1634-15-osalvador@suse.de> In-Reply-To: <20200922135650.1634-15-osalvador@suse.de> Accept-Language: ja-JP, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: suse.de; dkim=none (message not signed) header.d=none;suse.de; dmarc=none action=none header.from=nec.com; x-originating-ip: [165.225.110.205] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 0da4b89b-d1a5-4525-620b-08d85f93ed16 x-ms-traffictypediagnostic: TY1PR01MB1820: x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:8882; 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x-ms-exchange-antispam-messagedata: 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 Content-Type: text/plain; charset="iso-2022-jp" Content-ID: <6931F602FB5A69439A66B8F1D9A6335B@jpnprd01.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: nec.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: TY2PR01MB3210.jpnprd01.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 0da4b89b-d1a5-4525-620b-08d85f93ed16 X-MS-Exchange-CrossTenant-originalarrivaltime: 23 Sep 2020 07:40:21.3564 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: e67df547-9d0d-4f4d-9161-51c6ed1f7d11 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: lRLl8TCDDN+4U8RTS3AiJQgFkq9IRSiVoYA69H1Q75oh4aOwHnrHfS25TNImtDi5TNqRBfjAbJ6lZNokPgVm5g== X-MS-Exchange-Transport-CrossTenantHeadersStamped: TY1PR01MB1820 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 22, 2020 at 03:56:50PM +0200, Oscar Salvador wrote: > Aristeu Rozanski reported that a customer test case started > to report -EBUSY after the hwpoison rework patchset. >=20 > There is a race window between spotting a free page and taking it off > its buddy freelist, so it might be that by the time we try to take it off= , > the page has been already allocated. >=20 > This patch tries to handle such race window by trying to handle the new > type of page again if the page was allocated under us. >=20 > Signed-off-by: Oscar Salvador > Reported-by: Aristeu Rozanski > Tested-by: Aristeu Rozanski Acked-by: Naoya Horiguchi > --- > mm/memory-failure.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) >=20 > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index 46b1821d2817..8f23d3c7a0a2 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -1903,6 +1903,7 @@ int soft_offline_page(unsigned long pfn, int flags) > { > int ret; > struct page *page; > + bool try_again =3D true; > =20 > if (!pfn_valid(pfn)) > return -ENXIO; > @@ -1918,6 +1919,7 @@ int soft_offline_page(unsigned long pfn, int flags) > return 0; > } > =20 > +retry: > get_online_mems(); > ret =3D get_any_page(page, pfn, flags); > put_online_mems(); > @@ -1925,7 +1927,10 @@ int soft_offline_page(unsigned long pfn, int flags= ) > if (ret > 0) > ret =3D soft_offline_in_use_page(page); > else if (ret =3D=3D 0) > - ret =3D soft_offline_free_page(page); > + if (soft_offline_free_page(page) && try_again) { > + try_again =3D false; > + goto retry; > + } > =20 > return ret; > } > --=20 > 2.26.2 > =