From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5E6CBC2BB55 for ; Tue, 7 Apr 2020 13:54:40 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 209A92078A for ; Tue, 7 Apr 2020 13:54:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ZIEzj8Kp" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 209A92078A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 0F8DC8E002B; Tue, 7 Apr 2020 09:54:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 089D38E002A; Tue, 7 Apr 2020 09:54:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E621E8E002D; Tue, 7 Apr 2020 09:54:34 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0086.hostedemail.com [216.40.44.86]) by kanga.kvack.org (Postfix) with ESMTP id BEAEA8E002B for ; Tue, 7 Apr 2020 09:54:34 -0400 (EDT) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 7DB17121A for ; Tue, 7 Apr 2020 13:54:34 +0000 (UTC) X-FDA: 76681204068.21.stick53_621a471604608 X-HE-Tag: stick53_621a471604608 X-Filterd-Recvd-Size: 5915 Received: from us-smtp-delivery-1.mimecast.com (us-smtp-1.mimecast.com [205.139.110.61]) by imf35.hostedemail.com (Postfix) with ESMTP for ; Tue, 7 Apr 2020 13:54:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586267673; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+hECXe/ScdXiWieGl51KSz97pYlZ6hab45z2McF4NSw=; b=ZIEzj8KpFxNXIu11+YKcoBOUmGYfqYGIx6TpvAiZbL3TbESAJMRyp0IhunSkaBDXf3fR5Y bIklxxGJEnbDUIuAIcpFhaalyD9j1OuUBoF/zaczBPvuRvUDT5Ck5KkZcrZWFAXgibrcwB OG+bI2K3KPbGhFnmqYXrm6+k+PzzoMg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-420-2W7s--LtNgSfmWht8rBhpw-1; Tue, 07 Apr 2020 09:54:30 -0400 X-MC-Unique: 2W7s--LtNgSfmWht8rBhpw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8BFE21088384; Tue, 7 Apr 2020 13:54:26 +0000 (UTC) Received: from t480s.redhat.com (ovpn-114-167.ams2.redhat.com [10.36.114.167]) by smtp.corp.redhat.com (Postfix) with ESMTP id 03C8A96FB1; Tue, 7 Apr 2020 13:54:23 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, David Hildenbrand , Nathan Fontenot , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Michal Hocko , Andrew Morton , Oscar Salvador , Baoquan He , Wei Yang Subject: [PATCH v1 1/2] powerpc/pseries/hotplug-memory: stop checking is_mem_section_removable() Date: Tue, 7 Apr 2020 15:54:15 +0200 Message-Id: <20200407135416.24093-2-david@redhat.com> In-Reply-To: <20200407135416.24093-1-david@redhat.com> References: <20200407135416.24093-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Content-Transfer-Encoding: quoted-printable 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: In commit 53cdc1cb29e8 ("drivers/base/memory.c: indicate all memory blocks as removable"), the user space interface to compute whether a memo= ry block can be offlined (exposed via /sys/devices/system/memory/memoryX/removable) has effectively been deprecated. We want to remove the leftovers of the kernel implementation. When offlining a memory block (mm/memory_hotplug.c:__offline_pages()), we'll start by: 1. Testing if it contains any holes, and reject if so 2. Testing if pages belong to different zones, and reject if so 3. Isolating the page range, checking if it contains any unmovable pages Using is_mem_section_removable() before trying to offline is not only rac= y, it can easily result in false positives/negatives. Let's stop manually checking is_mem_section_removable(), and let device_offline() handle it completely instead. We can remove the racy is_mem_section_removable() implementation next. We now take more locks (e.g., memory hotplug lock when offlining and the zone lock when isolating), but maybe we should optimize that implementation instead if this ever becomes a real problem (after all, memory unplug is already an expensive operation). We started using is_mem_section_removable() in commit 51925fb3c5c9 ("powerpc/pseries: Implement memory hotplug remove in the kernel"), with the initial hotremove support of lmbs. Cc: Nathan Fontenot Cc: Michael Ellerman Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michal Hocko Cc: Andrew Morton Cc: Oscar Salvador Cc: Baoquan He Cc: Wei Yang Signed-off-by: David Hildenbrand --- .../platforms/pseries/hotplug-memory.c | 26 +++---------------- 1 file changed, 3 insertions(+), 23 deletions(-) diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/power= pc/platforms/pseries/hotplug-memory.c index b2cde1732301..5ace2f9a277e 100644 --- a/arch/powerpc/platforms/pseries/hotplug-memory.c +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c @@ -337,39 +337,19 @@ static int pseries_remove_mem_node(struct device_no= de *np) =20 static bool lmb_is_removable(struct drmem_lmb *lmb) { - int i, scns_per_block; - bool rc =3D true; - unsigned long pfn, block_sz; - u64 phys_addr; - if (!(lmb->flags & DRCONF_MEM_ASSIGNED)) return false; =20 - block_sz =3D memory_block_size_bytes(); - scns_per_block =3D block_sz / MIN_MEMORY_BLOCK_SIZE; - phys_addr =3D lmb->base_addr; - #ifdef CONFIG_FA_DUMP /* * Don't hot-remove memory that falls in fadump boot memory area * and memory that is reserved for capturing old kernel memory. */ - if (is_fadump_memory_area(phys_addr, block_sz)) + if (is_fadump_memory_area(lmb->base_addr, memory_block_size_bytes())) return false; #endif - - for (i =3D 0; i < scns_per_block; i++) { - pfn =3D PFN_DOWN(phys_addr); - if (!pfn_in_present_section(pfn)) { - phys_addr +=3D MIN_MEMORY_BLOCK_SIZE; - continue; - } - - rc =3D rc && is_mem_section_removable(pfn, PAGES_PER_SECTION); - phys_addr +=3D MIN_MEMORY_BLOCK_SIZE; - } - - return rc; + /* device_offline() will determine if we can actually remove this lmb *= / + return true; } =20 static int dlpar_add_lmb(struct drmem_lmb *); --=20 2.25.1