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a="208697276" X-IronPort-AV: E=Sophos;i="5.81,244,1610438400"; d="scan'208";a="208697276" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Mar 2021 08:29:39 -0800 IronPort-SDR: xfqavqvf/Q0gVTpWY4GxfHOXj9kaFU8+WFvbVgS8pgLZG1ix1w4s9a3BS98RLT7M+ItzKo7tSo qEGAsaM36rYA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.81,244,1610438400"; d="scan'208";a="387388874" Received: from fmsmsx601.amr.corp.intel.com ([10.18.126.81]) by orsmga002.jf.intel.com with ESMTP; 12 Mar 2021 08:29:39 -0800 Received: from fmsmsx611.amr.corp.intel.com (10.18.126.91) by fmsmsx601.amr.corp.intel.com (10.18.126.81) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Fri, 12 Mar 2021 08:29:38 -0800 Received: from fmsmsx610.amr.corp.intel.com (10.18.126.90) by fmsmsx611.amr.corp.intel.com (10.18.126.91) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Fri, 12 Mar 2021 08:29:38 -0800 Received: from fmsmsx610.amr.corp.intel.com ([10.18.126.90]) by fmsmsx610.amr.corp.intel.com ([10.18.126.90]) with mapi id 15.01.2106.013; Fri, 12 Mar 2021 08:29:38 -0800 From: "Luck, Tony" To: Aili Yao CC: =?iso-2022-jp?B?SE9SSUdVQ0hJIE5BT1lBKBskQktZOH0hIUQ+TGkbKEIp?= , Oscar Salvador , "david@redhat.com" , "akpm@linux-foundation.org" , "bp@alien8.de" , "tglx@linutronix.de" , "mingo@redhat.com" , "hpa@zytor.com" , "x86@kernel.org" , "linux-edac@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "yangfeng1@kingsoft.com" , "sunhao2@kingsoft.com" Subject: RE: [PATCH] mm,hwpoison: return -EBUSY when page already poisoned Thread-Topic: [PATCH] mm,hwpoison: return -EBUSY when page already poisoned Thread-Index: AQHXCnz5ja9ELypBUEatGW66U99st6pnoa2AgAEgN4CAAIHfAIAAAyEAgAAQXwD//9g7gIABDSmAgAALNoCAB2DqAIAAiu0AgABOzQD//+3L0IABObiAgAAiT4CAACi3AIAAmjmAgACgEACAAGnOwIAHwDQAgAHAYACAAADA4IABX0yAgAAnh8A= Date: Fri, 12 Mar 2021 16:29:37 +0000 Message-ID: <3900f518d1324c388be52cf81f5220e4@intel.com> References: <20210303115710.2e9f8e23@alex-virtual-machine> <20210303163912.3d508e0f@alex-virtual-machine> <1a78e9abdc134e35a5efcbf6b2fd2263@intel.com> <20210304101653.546a9da1@alex-virtual-machine> <20210304121941.667047c3@alex-virtual-machine> <20210304144524.795872d7@alex-virtual-machine> <20210304235720.GA215567@agluck-desk2.amr.corp.intel.com> <20210305093016.40c87375@alex-virtual-machine> <20210310141042.4db9ea29@alex-virtual-machine> <20210311085529.GA22268@hori.linux.bs1.fc.nec.co.jp> <20210312135531.72e33b35@alex-virtual-machine> In-Reply-To: <20210312135531.72e33b35@alex-virtual-machine> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: dlp-product: dlpe-windows dlp-reaction: no-action dlp-version: 11.5.1.3 x-originating-ip: [10.1.200.100] Content-Type: text/plain; charset="iso-2022-jp" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 44136E005F08 X-Stat-Signature: mteqmc9ra48n13mrkkjf7rxqqk3pn48x Received-SPF: none (intel.com>: No applicable sender policy available) receiver=imf05; identity=mailfrom; envelope-from=""; helo=mga01.intel.com; client-ip=192.55.52.88 X-HE-DKIM-Result: none/none X-HE-Tag: 1615566581-606301 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > Sorry to interrupt as I am really confused here: > If it's a copyin case, has the page been mapped for the current process? Yes. The kernel has the current process mapped to the low address range and code like get_user(), put_user() "simply" reaches down to those address= es (maybe not so simply, as the access needs to be within a STAC/CLAC section of code on modern CPUs, and the access instruction needs an entry in EXTABL= E so that the page fault handler can fix it if there isn't a page mapped at t= he user address). > will memory_failure() find it and unmap it? if succeed, then the current = will be > signaled with correct vaddr and shift? That's a very good question. I didn't see a SIGBUS when I first wrote this= code, hence all the p->mce_vaddr. But now I'm a) not sure why there wasn't a signal b) if we are to fix the problems noted by AndyL, need to make sure that the= re isn't a SIGBUS > Maybe the mce_vaddr is set correctly, but we may lost the correct page sh= ift? Yes. There is a hard-coded PAGE_SHIFT for this case - which may not match t= he actual page size. > And for copyin case, we don't need to call set_mce_nospec()? Yes. We should. Thanks for your good questions. -Tony