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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 58546C3A5A2 for ; Tue, 3 Sep 2019 09:46:44 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2AAA3206BB for ; Tue, 3 Sep 2019 09:46:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="myVj7mW3" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2AAA3206BB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=kEw4qAbvbYF0aWmlggtg20b3Udv+SxtuZRkPn0Mwgk0=; b=myVj7mW3GkdPsTH5tKo2rvuS1V iVXGZXj9+/prnKPFJ2YI3eR/ES8JP/v1iOfiCIt7op2kG88Fz3rd3x2S5J6jdBPOq4mFwmKW8y0eV kgfUdQCAXbXk1u9GgWSM0nHnfbAG44MA2jFqWYYmjIFov8KEXLDeIJj7owvhE07fdi+zN5EmSuRG0 A6ai3h1Ym3J3fQ6M8NJaPx015sVeQSSec8UpRSBXbO6sUYVxu5bmeA+H1rJ33Om6rXyswL0YpYJaF sQrOQKK9ILEhXcf/HPR00+RqAhTv/WXh+xs7cR6PQgBKnXu+7epgd69oKbLcSIiqGUjppWqvqwvCc Pbt39g4g==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1i55OU-0007Uy-0a; Tue, 03 Sep 2019 09:46:34 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1i55O5-0007BW-3d for linux-arm-kernel@lists.infradead.org; Tue, 03 Sep 2019 09:46:10 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 931B91570; Tue, 3 Sep 2019 02:46:08 -0700 (PDT) Received: from p8cg001049571a15.blr.arm.com (p8cg001049571a15.blr.arm.com [10.162.42.170]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id B19A73F59C; Tue, 3 Sep 2019 02:46:01 -0700 (PDT) From: Anshuman Khandual To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, akpm@linux-foundation.org, catalin.marinas@arm.com, will@kernel.org Subject: [PATCH V7 1/3] mm/hotplug: Reorder memblock_[free|remove]() calls in try_remove_memory() Date: Tue, 3 Sep 2019 15:15:56 +0530 Message-Id: <1567503958-25831-2-git-send-email-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1567503958-25831-1-git-send-email-anshuman.khandual@arm.com> References: <1567503958-25831-1-git-send-email-anshuman.khandual@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190903_024609_519861_8B5D1523 X-CRM114-Status: GOOD ( 12.40 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, mhocko@suse.com, david@redhat.com, ira.weiny@intel.com, steve.capper@arm.com, mgorman@techsingularity.net, steven.price@arm.com, broonie@kernel.org, cai@lca.pw, ard.biesheuvel@arm.com, cpandya@codeaurora.org, arunks@codeaurora.org, dan.j.williams@intel.com, Robin.Murphy@arm.com, logang@deltatee.com, valentin.schneider@arm.com, suzuki.poulose@arm.com, osalvador@suse.de MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Memory hot remove uses get_nid_for_pfn() while tearing down linked sysfs entries between memory block and node. It first checks pfn validity with pfn_valid_within() before fetching nid. With CONFIG_HOLES_IN_ZONE config (arm64 has this enabled) pfn_valid_within() calls pfn_valid(). pfn_valid() is an arch implementation on arm64 (CONFIG_HAVE_ARCH_PFN_VALID) which scans all mapped memblock regions with memblock_is_map_memory(). This creates a problem in memory hot remove path which has already removed given memory range from memory block with memblock_[remove|free] before arriving at unregister_mem_sect_under_nodes(). Hence get_nid_for_pfn() returns -1 skipping subsequent sysfs_remove_link() calls leaving node <-> memory block sysfs entries as is. Subsequent memory add operation hits BUG_ON() because of existing sysfs entries. [ 62.007176] NUMA: Unknown node for memory at 0x680000000, assuming node 0 [ 62.052517] ------------[ cut here ]------------ [ 62.053211] kernel BUG at mm/memory_hotplug.c:1143! [ 62.053868] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP [ 62.054589] Modules linked in: [ 62.054999] CPU: 19 PID: 3275 Comm: bash Not tainted 5.1.0-rc2-00004-g28cea40b2683 #41 [ 62.056274] Hardware name: linux,dummy-virt (DT) [ 62.057166] pstate: 40400005 (nZcv daif +PAN -UAO) [ 62.058083] pc : add_memory_resource+0x1cc/0x1d8 [ 62.058961] lr : add_memory_resource+0x10c/0x1d8 [ 62.059842] sp : ffff0000168b3ce0 [ 62.060477] x29: ffff0000168b3ce0 x28: ffff8005db546c00 [ 62.061501] x27: 0000000000000000 x26: 0000000000000000 [ 62.062509] x25: ffff0000111ef000 x24: ffff0000111ef5d0 [ 62.063520] x23: 0000000000000000 x22: 00000006bfffffff [ 62.064540] x21: 00000000ffffffef x20: 00000000006c0000 [ 62.065558] x19: 0000000000680000 x18: 0000000000000024 [ 62.066566] x17: 0000000000000000 x16: 0000000000000000 [ 62.067579] x15: ffffffffffffffff x14: ffff8005e412e890 [ 62.068588] x13: ffff8005d6b105d8 x12: 0000000000000000 [ 62.069610] x11: ffff8005d6b10490 x10: 0000000000000040 [ 62.070615] x9 : ffff8005e412e898 x8 : ffff8005e412e890 [ 62.071631] x7 : ffff8005d6b105d8 x6 : ffff8005db546c00 [ 62.072640] x5 : 0000000000000001 x4 : 0000000000000002 [ 62.073654] x3 : ffff8005d7049480 x2 : 0000000000000002 [ 62.074666] x1 : 0000000000000003 x0 : 00000000ffffffef [ 62.075685] Process bash (pid: 3275, stack limit = 0x00000000d754280f) [ 62.076930] Call trace: [ 62.077411] add_memory_resource+0x1cc/0x1d8 [ 62.078227] __add_memory+0x70/0xa8 [ 62.078901] probe_store+0xa4/0xc8 [ 62.079561] dev_attr_store+0x18/0x28 [ 62.080270] sysfs_kf_write+0x40/0x58 [ 62.080992] kernfs_fop_write+0xcc/0x1d8 [ 62.081744] __vfs_write+0x18/0x40 [ 62.082400] vfs_write+0xa4/0x1b0 [ 62.083037] ksys_write+0x5c/0xc0 [ 62.083681] __arm64_sys_write+0x18/0x20 [ 62.084432] el0_svc_handler+0x88/0x100 [ 62.085177] el0_svc+0x8/0xc Re-ordering memblock_[free|remove]() with arch_remove_memory() solves the problem on arm64 as pfn_valid() behaves correctly and returns positive as memblock for the address range still exists. arch_remove_memory() removes applicable memory sections from zone with __remove_pages() and tears down kernel linear mapping. Removing memblock regions afterwards is safe because there is no other memblock (bootmem) allocator user that late. So nobody is going to allocate from the removed range just to blow up later. Also nobody should be using the bootmem allocated range else we wouldn't allow to remove it. So reordering is indeed safe. Reviewed-by: David Hildenbrand Reviewed-by: Oscar Salvador Acked-by: Mark Rutland Acked-by: Michal Hocko Signed-off-by: Anshuman Khandual --- mm/memory_hotplug.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index c73f09913165..355c466e0621 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1770,13 +1770,13 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size) /* remove memmap entry */ firmware_map_remove(start, start + size, "System RAM"); - memblock_free(start, size); - memblock_remove(start, size); /* remove memory block devices before removing memory */ remove_memory_block_devices(start, size); arch_remove_memory(nid, start, size, NULL); + memblock_free(start, size); + memblock_remove(start, size); __release_memory_resource(start, size); try_offline_node(nid); -- 2.20.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel