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=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 9EFD6C2BB1D for ; Tue, 14 Apr 2020 23:24:46 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1FF8120768 for ; Tue, 14 Apr 2020 23:24:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=intel-com.20150623.gappssmtp.com header.i=@intel-com.20150623.gappssmtp.com header.b="jzOLfaRW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1FF8120768 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id AA9388E0003; Tue, 14 Apr 2020 19:24:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A5A2C8E0001; Tue, 14 Apr 2020 19:24:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 96FA18E0003; Tue, 14 Apr 2020 19:24:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0215.hostedemail.com [216.40.44.215]) by kanga.kvack.org (Postfix) with ESMTP id 7D4808E0001 for ; Tue, 14 Apr 2020 19:24:44 -0400 (EDT) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 4173F180AD802 for ; Tue, 14 Apr 2020 23:24:44 +0000 (UTC) X-FDA: 76708042488.29.cat11_63859dab2263e X-HE-Tag: cat11_63859dab2263e X-Filterd-Recvd-Size: 7514 Received: from mail-ed1-f65.google.com (mail-ed1-f65.google.com [209.85.208.65]) by imf21.hostedemail.com (Postfix) with ESMTP for ; Tue, 14 Apr 2020 23:24:43 +0000 (UTC) Received: by mail-ed1-f65.google.com with SMTP id i7so2012478edq.3 for ; Tue, 14 Apr 2020 16:24:43 -0700 (PDT) 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=X5OsVs88sB9xlVwRz9lsvoy0ZDu9Or4RqzhCODwES24=; b=jzOLfaRWwFpW42j/yqXoBVGCogkzhn9+bk/UKbl2xZfw7UkynvU/lIqI8CiTyjWWjm G8Y+wTI5B4acuj+SYU1KDts8MFrRK7PKxy5XCDe/fb8VBV1VXHkedLZFvadlp0yo1ZRO ss8cpKOse0J+nYcqJ1UXL3AA9ierLmBSa2+lNVKhGLsk0NCC2bBjsurjJx5tprntBccU IszgRJQBYcMo/DcppSiyH3Eg3qUAqN4JCGdkDvWvXROAJYJkIBHze09FiI9WcmZ0WFDv NlOLtoKeCCkkEHoogM/RJBUfw26xtGmNg2+1Z7efvee/3XDo1QomgxmsFtMuwuferKUU gNIw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=X5OsVs88sB9xlVwRz9lsvoy0ZDu9Or4RqzhCODwES24=; b=GuMS9TT68oWFvugv60ywC4u5Dib/7YG1dX7fSiI4DHGoAMMzYKuu8VwKR41GtpJK9I UGLf5CbA86CIYZ3TQdG4NKaYuI0BGYIXimHpzIkiM72XZVfS6tBR+taUA5BPAjnCJq5m w6gHGpy7UNGs0Jp2ufVEfogG801wUqRxFxD1T3STJLw01jgxivBzrvE3yobo2IE1f9vT 3rUjLkqmgjvBJcjjjLwLS6hMCMaHzlQnfj+wLYI/trquzBsRYOERN6D68fCPumLT4y1J tCZ7ZxDKUt7ZaWSTKg7zUTA0bNdyMbR+wPja5XP6oIipQ62SKzRx8m5WuwZIMTLtZ5/o eljQ== X-Gm-Message-State: AGi0PuZVZDB3bScc7f16z9FJzcXR8lofRpxGaacwI49lil5aSMUW+f7V 2nFUapkMpU6YqYfrynfo8mtMS35/XYF5Y1sH73NWwQ== X-Google-Smtp-Source: APiQypLM8bK4OO5YPBfMQuEL2SNiblaUsQYWa1PZtj9aDsYaSiN/q+av8+TDSmjhnRvwqlxcznlcb6pWVLkyY89jY9M= X-Received: by 2002:a50:d847:: with SMTP id v7mr22085369edj.154.1586906682440; Tue, 14 Apr 2020 16:24:42 -0700 (PDT) MIME-Version: 1.0 References: <20200414225029.709-1-vishal.l.verma@intel.com> In-Reply-To: <20200414225029.709-1-vishal.l.verma@intel.com> From: Dan Williams Date: Tue, 14 Apr 2020 16:24:31 -0700 Message-ID: Subject: Re: [PATCH v2] mm/memory_hotplug: refrain from adding memory into an impossible node To: Vishal Verma Cc: Linux MM , linux-nvdimm , David Hildenbrand , Dave Hansen 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, Apr 14, 2020 at 3:50 PM Vishal Verma wrote: > > A misbehaving qemu created a situation where the ACPI SRAT table > advertised one fewer proximity domains than intended. The NFIT table did > describe all the expected proximity domains. This caused the device dax > driver to assign an impossible target_node to the device, and when > hotplugged as system memory, this would fail with the following > signature: > > [ +0.001627] BUG: kernel NULL pointer dereference, address: 0000000000000088 > [ +0.001331] #PF: supervisor read access in kernel mode > [ +0.000975] #PF: error_code(0x0000) - not-present page > [ +0.000976] PGD 80000001767d4067 P4D 80000001767d4067 PUD 10e0c4067 PMD 0 > [ +0.001338] Oops: 0000 [#1] SMP PTI > [ +0.000676] CPU: 4 PID: 22737 Comm: kswapd3 Tainted: G O 5.6.0-rc5 #9 > [ +0.001457] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), > BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 > [ +0.001990] RIP: 0010:prepare_kswapd_sleep+0x7c/0xc0 > [ +0.000780] Code: 89 df e8 87 fd ff ff 89 c2 31 c0 84 d2 74 e6 0f 1f 44 > 00 00 48 8b 05 fb af 7a 01 48 63 93 88 1d 01 00 48 8b > 84 d0 20 0f 00 00 <48> 3b 98 88 00 00 00 75 28 f0 80 a0 > 80 00 00 00 fe f0 80 a3 38 20 > [ +0.002877] RSP: 0018:ffffc900017a3e78 EFLAGS: 00010202 > [ +0.000805] RAX: 0000000000000000 RBX: ffff8881209e0000 RCX: 0000000000000000 > [ +0.001115] RDX: 0000000000000003 RSI: 0000000000000000 RDI: ffff8881209e0e80 > [ +0.001098] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000008000 > [ +0.001092] R10: 0000000000000000 R11: 0000000000000003 R12: 0000000000000003 > [ +0.001092] R13: 0000000000000003 R14: 0000000000000000 R15: ffffc900017a3ec8 > [ +0.001091] FS: 0000000000000000(0000) GS:ffff888318c00000(0000) knlGS:0000000000000000 > [ +0.001275] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ +0.000882] CR2: 0000000000000088 CR3: 0000000120b50002 CR4: 00000000001606e0 > [ +0.001095] Call Trace: > [ +0.000388] kswapd+0x103/0x520 > [ +0.000494] ? finish_wait+0x80/0x80 > [ +0.000547] ? balance_pgdat+0x5a0/0x5a0 > [ +0.000607] kthread+0x120/0x140 > [ +0.000508] ? kthread_create_on_node+0x60/0x60 > [ +0.000706] ret_from_fork+0x3a/0x50 > > Add a check in the add_memory path to ensure that the node to which we > are adding memory is in the node_possible_map > > Cc: David Hildenbrand > Cc: Dan Williams > Cc: Dave Hansen > Signed-off-by: Vishal Verma > --- > mm/memory_hotplug.c | 26 ++++++++++++++++++++++++++ > 1 file changed, 26 insertions(+) > > v2: > - Centralize the check in the add_memory path (David) > - Instead of failing, add the memory to a nearby node, while warning > (and tainting) to call out attention to the firmware bug (Dan) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 0a54ffac8c68..022df38a5d8a 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -980,6 +980,28 @@ static int check_hotplug_memory_range(u64 start, u64 size) > return 0; > } > > +/* > + * Check that the node provided for adding memory was valid. > + * If not, find the nearest valid node and add the memory there while > + * tainting the kernel and displaying a warning to bring attention to the > + * underlying firmware problem. > + * Return nid if valid, or an adjusted node number that can be used instead > + * if the original nid was not valid > + */ > +static int check_hotplug_node(int nid) > +{ > + int alt_nid; > + > + if (node_possible(nid)) > + return nid; > + > + alt_nid = numa_map_to_online_node(nid); > + WARN_TAINT(1, TAINT_FIRMWARE_WORKAROUND, > + "node %d expected, but was absent from the node_possible_map, using %d instead\n", > + nid, alt_nid); > + return alt_nid; > +} > + > static int online_memory_block(struct memory_block *mem, void *arg) > { > return device_online(&mem->dev); > @@ -1005,6 +1027,10 @@ int __ref add_memory_resource(int nid, struct resource *res) > if (ret) > return ret; > > + nid = check_hotplug_node(nid); > + if (nid < 0) > + return -ENXIO; > + It seems CONFIG_MEMORY_HOTPLUG does not require numa support, so numa_map_to_online_node() might legitimately return NUMA_NO_NODE. So perhaps this error return should be skipped in the CONFIG_NUMA=n case and just use 0 which is the decision that memory_add_physaddr_to_nid() takes.