Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934564AbbHLJNs (ORCPT ); Wed, 12 Aug 2015 05:13:48 -0400 Received: from blu004-omc1s35.hotmail.com ([65.55.116.46]:51474 "EHLO BLU004-OMC1S35.hotmail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932119AbbHLJNq (ORCPT ); Wed, 12 Aug 2015 05:13:46 -0400 X-TMN: [4eAYufqQi7A8RDPY/Sklg5UUvjDpuXiG] X-Originating-Email: [wanpeng.li@hotmail.com] Message-ID: Subject: Re: [PATCH v2 5/5] mm/hwpoison: replace most of put_page in memory error handling by put_hwpoison_page To: Naoya Horiguchi References: <1439206103-86829-1-git-send-email-wanpeng.li@hotmail.com> <20150812085525.GD32192@hori1.linux.bs1.fc.nec.co.jp> CC: Andrew Morton , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" From: Wanpeng Li Date: Wed, 12 Aug 2015 17:13:39 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:38.0) Gecko/20100101 Thunderbird/38.0.1 MIME-Version: 1.0 In-Reply-To: <20150812085525.GD32192@hori1.linux.bs1.fc.nec.co.jp> Content-Type: text/plain; charset="iso-2022-jp" Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 12 Aug 2015 09:13:44.0173 (UTC) FILETIME=[2FFE39D0:01D0D4DF] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2024 Lines: 57 On 8/12/15 4:55 PM, Naoya Horiguchi wrote: > On Mon, Aug 10, 2015 at 07:28:23PM +0800, Wanpeng Li wrote: >> Replace most of put_page in memory error handling by put_hwpoison_page, >> except the ones at the front of soft_offline_page since the page maybe >> THP page and the get refcount in madvise_hwpoison is against the single >> 4KB page instead of the logic in get_hwpoison_page. >> >> Signed-off-by: Wanpeng Li > # Sorry for my late response. > > If I read correctly, get_user_pages_fast() (called by madvise_hwpoison) > for a THP tail page takes a refcount from each of head and tail page. > gup_huge_pmd() does this in the fast path, and get_page_foll() does this > in the slow path (maybe via the following code path) > > get_user_pages_unlocked > __get_user_pages_unlocked > __get_user_pages_locked > __get_user_pages > follow_page_mask > follow_trans_huge_pmd (with FOLL_GET set) > get_page_foll > > So this should be equivalent to what get_hwpoison_page() does for thp pages > with regard to refcounting. > > And I'm expecting that a refcount taken by get_hwpoison_page() is released > by put_hwpoison_page() even if the page's status is changed during error > handling (the typical (or only?) case is successful thp split.) Indeed. :-) > > So I think you can apply put_hwpoison_page() for 3 more callsites in > mm/memory-failure.c. > - MF_MSG_POISONED_HUGE case I have already done this in my patch. > - "soft offline: %#lx page already poisoned" case (you mentioned above) > - "soft offline: %#lx: failed to split THP" case (you mentioned above) You are right, I will send a patch rebased on this one since they are merged. Regards, Wanpeng Li > > Thanks, > Naoya Horiguchi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/