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[209.85.220.65]) by mx.google.com with SMTPS id m10sor6616279otl.112.2019.05.07.13.46.19 for (Google Transport Security); Tue, 07 May 2019 13:46:19 -0700 (PDT) Received-SPF: pass (google.com: domain of dan.j.williams@intel.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@intel-com.20150623.gappssmtp.com header.s=20150623 header.b=rqW6lucK; spf=pass (google.com: domain of dan.j.williams@intel.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=dan.j.williams@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Fw0JPQ4oQ07pMZfSEOmqFo0Ax/JNe6lqDNiuIeW+cfk=; b=rqW6lucK5GLSkk6D3VC83NNNr3p5l4cDVk4n80Uvm322BBV2qCuKSPr4z+P2ezcoyK z+YMgkO0V+5hEmcMr0MwF6O3QHG8xWVY2eTA1Py3k6awm18aqMlPP98eZujqBEdbRRXN aS93k1uMcPJFXIHF98HnDfB8WCQgSAWAn+PzoKcCdVTC+uJmNJ+7TTcrUEmBZNFgGikS JoN377FDE4nzpHgH/fCwVvnpugUJXF2ApAVZaCrgrLXf7ZjFcE/OLNwmWNUpvbW/wIQU Uwg4mKk8U4/mWeh5D1XY1VYZpFjHtv4IPmwLoWQVjBRPrwTp5axa3EA9O5FG/AT874cG VNvQ== X-Google-Smtp-Source: APXvYqwkL7vHIYJxD+HfiXZUkr4PGh3XR7bd+koUKuRLubXL7y6kGEyKk74Z2RGz0ad/moc44qYziRyn+VmkpRZHHO8= X-Received: by 2002:a9d:6f19:: with SMTP id n25mr2402081otq.367.1557261979262; Tue, 07 May 2019 13:46:19 -0700 (PDT) MIME-Version: 1.0 References: <20190507183804.5512-1-david@redhat.com> <20190507183804.5512-3-david@redhat.com> In-Reply-To: <20190507183804.5512-3-david@redhat.com> From: Dan Williams Date: Tue, 7 May 2019 13:46:08 -0700 Message-ID: Subject: Re: [PATCH v2 2/8] s390x/mm: Implement arch_remove_memory() To: David Hildenbrand Cc: Linux MM , Linux Kernel Mailing List , linux-ia64@vger.kernel.org, linuxppc-dev , linux-s390 , Linux-sh , Andrew Morton , Martin Schwidefsky , Heiko Carstens , Michal Hocko , Mike Rapoport , Vasily Gorbik , Oscar Salvador 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: On Tue, May 7, 2019 at 11:38 AM David Hildenbrand wrote: > > Will come in handy when wanting to handle errors after > arch_add_memory(). > > Cc: Martin Schwidefsky > Cc: Heiko Carstens > Cc: Andrew Morton > Cc: Michal Hocko > Cc: Mike Rapoport > Cc: David Hildenbrand > Cc: Vasily Gorbik > Cc: Oscar Salvador > Signed-off-by: David Hildenbrand > --- > arch/s390/mm/init.c | 13 +++++++------ > 1 file changed, 7 insertions(+), 6 deletions(-) > > diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c > index 31b1071315d7..1e0cbae69f12 100644 > --- a/arch/s390/mm/init.c > +++ b/arch/s390/mm/init.c > @@ -237,12 +237,13 @@ int arch_add_memory(int nid, u64 start, u64 size, > void arch_remove_memory(int nid, u64 start, u64 size, > struct vmem_altmap *altmap) > { > - /* > - * There is no hardware or firmware interface which could trigger a > - * hot memory remove on s390. So there is nothing that needs to be > - * implemented. > - */ > - BUG(); > + unsigned long start_pfn = start >> PAGE_SHIFT; > + unsigned long nr_pages = size >> PAGE_SHIFT; > + struct zone *zone; > + > + zone = page_zone(pfn_to_page(start_pfn)); Does s390 actually support passing in an altmap? If 'yes', I think it also needs the vmem_altmap_offset() fixup like x86-64: /* With altmap the first mapped page is offset from @start */ if (altmap) page += vmem_altmap_offset(altmap); ...but I suspect it does not support altmap since arch/s390/mm/vmem.c::vmemmap_populate() does not arrange for 'struct page' capacity to be allocated out of an altmap defined page pool. I think it would be enough to disallow any arch_add_memory() on s390 where @altmap is non-NULL. At least until s390 gains ZONE_DEVICE support and can enable the pmem use case.