From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1522656762; cv=none; d=google.com; s=arc-20160816; b=fiISMkgS3Uhfn8+Gb8wH2MuDPea7UvSMH6Ktnd2qVyd7kMxbfMacsf2vA66PuiJa7f 4gi1xfpfL4YbW4OMg/vmSMqdVmeUtXu4Hfj9JT0YOvr2/geAzWLCgu1lGE6uDp5Dln9X HAHHuMBEmyY78w+PRM+/O7bA2hMu8BGnF6zuRR4ZjnXsQ+JByRu/fhe197Rg0UBmnsBI UerSHMzmN4KKlVLmnNCSD+F1Pg8BwCiTpdZYPap6yk+lVjpcMx8VxF6YLsoweNBZcjfs ICBUC4p4KdIio2uHgu+Jz5a1LQtl0DsTTZlLa+sFek+y6u6l9uzbZi39cD73iKaIctM4 XqTQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :reply-to:message-id:subject:cc:to:from:date:dkim-signature :arc-authentication-results; bh=Tkizeu4ES2/0iv8vbUMdzBAfLkWTrhXB9M0mpsSJKvI=; b=cu7svbxew+Vak6MZaVvSNjL1tzD+HRrbWkzLh8ax3Jjeb45dERONNxU7sQWI6qxAI8 HP+EMno4owvLVPK0S916b8LJtWgqeZFUu4DNkLd8koVeg46Fi1M3f9DJlgmmQtN9ocPV 36/a+Moe4EUACi+fIaDgyjKt/LhNIQ81Yt5SEDmtdi+ZmtL0zHr9mebDW0gRPnOmDaWj QUElvE1du58Ap6pxpzlYaf7a0+HPc14JQloQ9QbN3VZt8qEapDKFX5cRjnCnQfX/lkcX BcXzCWOxdZamvo8LxgDDTPsb7EBfmR252+x49Yo96yJxSlpaA09HDvHDNxs2y/H3i8CH 7AgQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=WYzTv8QH; spf=pass (google.com: domain of richard.weiyang@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=richard.weiyang@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=WYzTv8QH; spf=pass (google.com: domain of richard.weiyang@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=richard.weiyang@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com X-Google-Smtp-Source: AIpwx48UwexeDBQgWIOOv/y4tITt2FXmRWTRV/eeMts290qnAk2QiSd0xogKSma9E3Wkosj5xNmWlw== Date: Mon, 2 Apr 2018 16:12:33 +0800 From: Wei Yang To: Jia He Cc: Wei Yang , Andrew Morton , Michal Hocko , Catalin Marinas , Mel Gorman , Will Deacon , Mark Rutland , Ard Biesheuvel , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Pavel Tatashin , Daniel Jordan , AKASHI Takahiro , Gioh Kim , Steven Sistare , Daniel Vacek , Eugeniu Rosca , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-mm@kvack.org, James Morse , Steve Capper , x86@kernel.org, Greg Kroah-Hartman , Kate Stewart , Philippe Ombredanne , Johannes Weiner , Kemi Wang , Petr Tesarik , YASUAKI ISHIMATSU , Andrey Ryabinin , Nikolay Borisov , Jia He Subject: Re: [PATCH v3 1/5] mm: page_alloc: remain memblock_next_valid_pfn() when CONFIG_HAVE_ARCH_PFN_VALID is enable Message-ID: <20180402081233.GA38180@WeideMacBook-Pro.local> Reply-To: Wei Yang References: <1522033340-6575-1-git-send-email-hejianet@gmail.com> <1522033340-6575-2-git-send-email-hejianet@gmail.com> <20180328091800.GB97260@WeideMacBook-Pro.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.1 (2017-09-22) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1595967673442117233?= X-GMAIL-MSGID: =?utf-8?q?1596621337622357107?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Wed, Mar 28, 2018 at 05:49:23PM +0800, Jia He wrote: > > >On 3/28/2018 5:18 PM, Wei Yang Wrote: >> Oops, I should reply this thread. Forget about the reply on another thread. >> >> On Sun, Mar 25, 2018 at 08:02:15PM -0700, Jia He wrote: >> > Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns >> > where possible") optimized the loop in memmap_init_zone(). But it causes >> > possible panic bug. So Daniel Vacek reverted it later. >> > >> Why this has a bug? Do you have some link about it? >> >> If the audience could know the potential risk, it would be helpful to review >> the code and decide whether to take it back. >Hi Wei >Paul firstly submit a commit b92df1de5 to improve the loop in >memmap_init_zone. >And Daniel tried to fix a bug_on panic issue on X86 in commit 864b75f9d6b >because >there is evidence that this bug_on was caused by b92df1de5 [1]. > >But things didn't get better, 864b75f9d6b caused booting hang issue on >arm{64} [2] >So maintainer decided to reverted both b92df1de5 and 864b75f9d6b > >[1] https://patchwork.kernel.org/patch/10251145/ >[2] https://lkml.org/lkml/2018/3/14/469 I took some time to look into the discussion, while the root cause seems not clear now? -- Wei Yang Help you, Help me