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[209.85.220.65]) by mx.google.com with SMTPS id m200sor208822itb.0.2019.01.10.18.41.55 for (Google Transport Security); Thu, 10 Jan 2019 18:41:55 -0800 (PST) Received-SPF: pass (google.com: domain of kernelfans@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b="MRa/9bfd"; spf=pass (google.com: domain of kernelfans@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=kernelfans@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=RfMVf92gzaxzMAZMAu2AYRtnc2xIj45ckuZbtAg6QGU=; b=MRa/9bfdZyRjEJLIeG7zx4theoKEg2zKgAgFkxZWKncN6J87EabS6DUt0NbHO1ShdA 5VCjc19Bfd313iZS4han3kE2BUIsu4KP2d0mnR+bdlN0tCmi2tAsGryx7UV1q55ZEDkD U9C9Ev40HlWbWLjIy8nxTZjhag0WOz4FJPnAsl9n+i+Rmg21C41DXjdU3LkKWbQvGoZ5 3WdypC25V/3ydUa1q5Ec6VDvN2voHGx1GAzSo1X9dXUgjVf7YXcUqN1EqW/9Mfk/66IV GWlzmqJSRzdVqnTD23i7h+2jp0MH6UX79KJSD6/npLCUrRTqSlN1Be8lwtxlIH/MJl4D C6fg== X-Google-Smtp-Source: ALg8bN7Gjki6FZggg6PyH5Cia7SKfuhztuj+BXYJGNQKyxr4jO6MOJX9oHMpyEvghsT3ptD0NxppM2zcXF6UenjhjZc= X-Received: by 2002:a24:7a94:: with SMTP id a142mr83215itc.88.1547174515528; Thu, 10 Jan 2019 18:41:55 -0800 (PST) MIME-Version: 1.0 References: <1546848299-23628-1-git-send-email-kernelfans@gmail.com> <20190108080538.GB4396@rapoport-lnx> <20190108090138.GB18718@MiWiFi-R3L-srv> <20190108154852.GC14063@rapoport-lnx> <20190109142516.GA14211@MiWiFi-R3L-srv> In-Reply-To: <20190109142516.GA14211@MiWiFi-R3L-srv> From: Pingfan Liu Date: Fri, 11 Jan 2019 10:41:44 +0800 Message-ID: Subject: Re: [PATCHv5] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr To: Baoquan He Cc: Mike Rapoport , linux-mm@kvack.org, kexec@lists.infradead.org, "Rafael J. Wysocki" , Len Brown , Andrew Morton , Mike Rapoport , Michal Hocko , Jonathan Corbet , Yaowei Bai , Nicholas Piggin , Naoya Horiguchi , Daniel Vacek , Mathieu Malaterre , Stefan Agner , Dave Young , yinghai@kernel.org, vgoyal@redhat.com, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" 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: Message-ID: <20190111024144._dvjHAFz7JlBJkrnxgICwUJU_cXOK4cJ7yLKtrnXBL0@z> On Wed, Jan 9, 2019 at 10:25 PM Baoquan He wrote: > > On 01/08/19 at 05:48pm, Mike Rapoport wrote: > > On Tue, Jan 08, 2019 at 05:01:38PM +0800, Baoquan He wrote: > > > Hi Mike, > > > > > > On 01/08/19 at 10:05am, Mike Rapoport wrote: > > > > I'm not thrilled by duplicating this code (yet again). > > > > I liked the v3 of this patch [1] more, assuming we allow bottom-up mode to > > > > allocate [0, kernel_start) unconditionally. > > > > I'd just replace you first patch in v3 [2] with something like: > > > > > > In initmem_init(), we will restore the top-down allocation style anyway. > > > While reserve_crashkernel() is called after initmem_init(), it's not > > > appropriate to adjust memblock_find_in_range_node(), and we really want > > > to find region bottom up for crashkernel reservation, no matter where > > > kernel is loaded, better call __memblock_find_range_bottom_up(). > > > > > > Create a wrapper to do the necessary handling, then call > > > __memblock_find_range_bottom_up() directly, looks better. > > > > What bothers me is 'the necessary handling' which is already done in > > several places in memblock in a similar, but yet slightly different way. > > The page aligning for start and the mirror flag setting, I suppose. > > > > memblock_find_in_range() and memblock_phys_alloc_nid() retry with different > > MEMBLOCK_MIRROR, but memblock_phys_alloc_try_nid() does that only when > > allocating from the specified node and does not retry when it falls back to > > any node. And memblock_alloc_internal() has yet another set of fallbacks. > > Get what you mean, seems they are trying to allocate within mirrorred > memory region, if fail, try the non-mirrorred region. If kernel data > allocation failed, no need to care about if it's movable or not, it need > to live firstly. For the bottom-up allocation wrapper, maybe we need do > like this too? > > > > > So what should be the necessary handling in the wrapper for > > __memblock_find_range_bottom_up() ? > > > > BTW, even without any memblock modifications, retrying allocation in > > reserve_crashkerenel() for different ranges, like the proposal at [1] would > > also work, wouldn't it? > > Yes, it also looks good. This patch only calls once, seems a simpler > line adding. > > In fact, below one and this patch, both is fine to me, as long as it > fixes the problem customers are complaining about. > It seems that there is divergence on opinion. Maybe it is easier to fix this bug by dyoung's patch. I will repost his patch. Thanks and regards, Pingfan > > > > [1] http://lists.infradead.org/pipermail/kexec/2017-October/019571.html > > Thanks > Baoquan