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Fri, 4 Sep 2020 02:02:05 +0000 From: =?iso-2022-jp?B?SE9SSUdVQ0hJIE5BT1lBKBskQktZOH0hIUQ+TGkbKEIp?= To: Oscar Salvador CC: "akpm@linux-foundation.org" , "mhocko@kernel.org" , "tony.luck@intel.com" , "cai@lca.pw" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" Subject: Re: [PATCH 1/4] mm,hwpoison: Take free pages off the buddy freelists Thread-Topic: [PATCH 1/4] mm,hwpoison: Take free pages off the buddy freelists Thread-Index: AQHWgQ3LrQfep9tTU0aEmz9PX/b1n6lXvKqA Date: Fri, 4 Sep 2020 02:02:05 +0000 Message-ID: <20200904020205.GA32236@hori.linux.bs1.fc.nec.co.jp> References: <20200902094510.10727-1-osalvador@suse.de> <20200902094510.10727-2-osalvador@suse.de> In-Reply-To: <20200902094510.10727-2-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: 744105e8-f5b9-4267-327e-08d85076861b x-ms-traffictypediagnostic: TYAPR01MB4416: x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:8273; 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> int res; > unsigned long page_flags; > + bool retry =3D true; > =20 > if (!sysctl_memory_failure_recovery) > panic("Memory failure on page %lx", pfn); > @@ -1364,10 +1365,20 @@ int memory_failure(unsigned long pfn, int flags) > * In fact it's dangerous to directly bump up page count from 0, > * that may make page_ref_freeze()/page_ref_unfreeze() mismatch. > */ > +try_again: > if (!(flags & MF_COUNT_INCREASED) && !get_hwpoison_page(p)) { > if (is_free_buddy_page(p)) { > - action_result(pfn, MF_MSG_BUDDY, MF_DELAYED); > - return 0; > + if (take_page_off_buddy(p)) { > + action_result(pfn, MF_MSG_BUDDY, MF_DELAYED); > + return 0; > + } else { > + /* We lost the race, try again */ > + if (retry) { > + retry =3D false; > + goto try_again; > + } You might need add calling action_result() here. > + return -EBUSY; > + } > } else { > action_result(pfn, MF_MSG_KERNEL_HIGH_ORDER, MF_IGNORED); > return -EBUSY; And the following block also handles buddy pages, so you could also call take_page_off_buddy() here? /* * We ignore non-LRU pages for good reasons. * - PG_locked is only well defined for LRU pages and a few others * - to avoid races with __SetPageLocked() * - to avoid races with __SetPageSlab*() (and more non-atomic ops) * The check (unnecessarily) ignores LRU pages being isolated and * walked by the page reclaim code, however that's not a big loss. */ shake_page(p, 0); /* shake_page could have turned it free. */ if (!PageLRU(p) && is_free_buddy_page(p)) { if (flags & MF_COUNT_INCREASED) action_result(pfn, MF_MSG_BUDDY, MF_DELAYED); else action_result(pfn, MF_MSG_BUDDY_2ND, MF_DELAYED); return 0; } Or if get_hwpoison_page() handles retry inside it as will be done in patch = 3/4, we don't need this block any more? Thanks, Naoya Horiguchi=