From patchwork Mon May 20 05:18:33 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anshuman Khandual X-Patchwork-Id: 10949877 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7128D912 for ; Mon, 20 May 2019 05:18:55 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 602CF28622 for ; Mon, 20 May 2019 05:18:55 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4B69E2861C; Mon, 20 May 2019 05:18:55 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id C57C728628 for ; Mon, 20 May 2019 05:18:54 +0000 (UTC) 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=syHT/G80Of1qKlP4e07W3dGSsOOr6lj/sCnWfiCq9XQ=; b=s7a/SkpR8ZGja/Q736k3PZBrDh ZesVUpgWqf69rsUtkKkpr2Y0Zd6znguymzHakvL6vSDrxggRDDm+iaGOpbxT0l2DLW16OS114X9Tf BIYZKF4C4/2l10A+sBGUKJWE786qfb32QHl7kUSkGFfMQpM6tj/Elh1wYNIl8GTqWp/f0AWwb2OUg mTZG87b0YlOztug86EkRvk9VhXUwI4igJH7Zd1Y5/sPbrBJA+MS1+5oZgd3cpMDZW4b5gpk0+8E9K PW6dQybT2KybEh8fWcnJYZwOWDHq4O4VOzhxMyCQZ4kuFSPOzDpA2lHhnpPR5P2Mj2gcmT8up7KTU GYUhdwpQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hSahF-0008CP-4F; Mon, 20 May 2019 05:18:49 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hSah3-00080R-Vq for linux-arm-kernel@lists.infradead.org; Mon, 20 May 2019 05:18:41 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id AD8FA80D; Sun, 19 May 2019 22:18:37 -0700 (PDT) Received: from p8cg001049571a15.blr.arm.com (p8cg001049571a15.blr.arm.com [10.162.41.132]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id E0D063F5AF; Sun, 19 May 2019 22:18:31 -0700 (PDT) From: Anshuman Khandual To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, akpm@linux-foundation.org, catalin.marinas@arm.com, will.deacon@arm.com Subject: [PATCH V4 1/4] mm/hotplug: Reorder arch_remove_memory() call in __remove_memory() Date: Mon, 20 May 2019 10:48:33 +0530 Message-Id: <1558329516-10445-2-git-send-email-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1558329516-10445-1-git-send-email-anshuman.khandual@arm.com> References: <1558329516-10445-1-git-send-email-anshuman.khandual@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190519_221838_389730_C6282C78 X-CRM114-Status: GOOD ( 13.38 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 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, mgorman@techsingularity.net, cai@lca.pw, ard.biesheuvel@arm.com, cpandya@codeaurora.org, james.morse@arm.com, dan.j.williams@intel.com, logang@deltatee.com, arunks@codeaurora.org, osalvador@suse.de MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP 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 arch_remove_memory() with memblock_[free|remove] 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. Acked-by: Michal Hocko Reviewed-by: David Hildenbrand Reviewed-by: Oscar Salvador Signed-off-by: Anshuman Khandual --- mm/memory_hotplug.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 328878b..1dbda48 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1850,10 +1850,10 @@ void __ref __remove_memory(int nid, u64 start, u64 size) /* remove memmap entry */ firmware_map_remove(start, start + size, "System RAM"); + arch_remove_memory(nid, start, size, NULL); memblock_free(start, size); memblock_remove(start, size); - arch_remove_memory(nid, start, size, NULL); __release_memory_resource(start, size); try_offline_node(nid);