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[209.132.183.28]) by mx.google.com with ESMTPS id i22si11977130qvh.223.2019.07.15.08.25.17 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 15 Jul 2019 08:25:17 -0700 (PDT) Received-SPF: pass (google.com: domain of oleg@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of oleg@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=oleg@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C825C8666A; Mon, 15 Jul 2019 15:25:16 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.43.17.136]) by smtp.corp.redhat.com (Postfix) with SMTP id 0060E1992C; Mon, 15 Jul 2019 15:25:14 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 15 Jul 2019 17:25:16 +0200 (CEST) Date: Mon, 15 Jul 2019 17:25:14 +0200 From: Oleg Nesterov To: Song Liu Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, matthew.wilcox@oracle.com, kirill.shutemov@linux.intel.com, peterz@infradead.org, rostedt@goodmis.org, kernel-team@fb.com, william.kucharski@oracle.com Subject: Re: [PATCH v7 2/4] uprobe: use original page when all uprobes are removed Message-ID: <20190715152513.GD1222@redhat.com> References: <20190625235325.2096441-1-songliubraving@fb.com> <20190625235325.2096441-3-songliubraving@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190625235325.2096441-3-songliubraving@fb.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Mon, 15 Jul 2019 15:25:16 +0000 (UTC) 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 06/25, Song Liu wrote: > > This patch allows uprobe to use original page when possible (all uprobes > on the page are already removed). I can't review. I do not understand vm enough. > + if (!is_register) { > + struct page *orig_page; > + pgoff_t index; > + > + index = vaddr_to_offset(vma, vaddr & PAGE_MASK) >> PAGE_SHIFT; > + orig_page = find_get_page(vma->vm_file->f_inode->i_mapping, > + index); > + > + if (orig_page) { > + if (pages_identical(new_page, orig_page)) { Shouldn't we at least check PageUptodate? and I am a bit surprised there is no simple way to unmap the old page in this case... Oleg.