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=-9.7 required=3.0 tests=BAYES_00, 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 21A62C433E2 for ; Wed, 9 Sep 2020 07:40:16 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8333B20732 for ; Wed, 9 Sep 2020 07:40:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8333B20732 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 022FE6B0075; Wed, 9 Sep 2020 03:40:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EEF126B007B; Wed, 9 Sep 2020 03:40:14 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DB6BF6B007D; Wed, 9 Sep 2020 03:40:14 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0244.hostedemail.com [216.40.44.244]) by kanga.kvack.org (Postfix) with ESMTP id C27E76B0075 for ; Wed, 9 Sep 2020 03:40:14 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 81848181AEF0B for ; Wed, 9 Sep 2020 07:40:14 +0000 (UTC) X-FDA: 77242724748.02.noise23_6210d9d270db Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin02.hostedemail.com (Postfix) with ESMTP id 6058310096C5A for ; Wed, 9 Sep 2020 07:40:14 +0000 (UTC) X-HE-Tag: noise23_6210d9d270db X-Filterd-Recvd-Size: 10131 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf35.hostedemail.com (Postfix) with ESMTP for ; Wed, 9 Sep 2020 07:40:13 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 4CE83B681; Wed, 9 Sep 2020 07:40:13 +0000 (UTC) Date: Wed, 9 Sep 2020 09:40:11 +0200 From: Michal Hocko To: Laurent Dufour Cc: akpm@linux-foundation.org, David Hildenbrand , Oscar Salvador , rafael@kernel.org, nathanl@linux.ibm.com, cheloha@linux.ibm.com, stable@vger.kernel.org, Greg Kroah-Hartman , linux-mm@kvack.org, LKML Subject: Re: [PATCH] mm: don't rely on system state to detect hot-plug operations Message-ID: <20200909074011.GD7348@dhcp22.suse.cz> References: <5cbd92e1-c00a-4253-0119-c872bfa0f2bc@redhat.com> <20200908170835.85440-1-ldufour@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200908170835.85440-1-ldufour@linux.ibm.com> X-Rspamd-Queue-Id: 6058310096C5A X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 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: [reposting because the malformed cc list confused my email client] On Tue 08-09-20 19:08:35, Laurent Dufour wrote: > In register_mem_sect_under_node() the system_state=E2=80=99s value is c= hecked to > detect whether the operation the call is made during boot time or durin= g an > hot-plug operation. Unfortunately, that check is wrong on some > architecture, and may lead to sections being registered under multiple > nodes if node's memory ranges are interleaved. Why is this check arch specific? > This can be seen on PowerPC LPAR after multiple memory hot-plug and > hot-unplug operations are done. At the next reboot the node's memory ra= nges > can be interleaved What is the exact memory layout? > and since the call to link_mem_sections() is made in > topology_init() while the system is in the SYSTEM_SCHEDULING state, the > node's id is not checked, and the sections registered multiple times. So a single memory section/memblock belongs to two numa nodes? > In > that case, the system is able to boot but later hot-plug operation may = lead > to this panic because the node's links are correctly broken: Correctly broken? Could you provide more details on the inconsistency please? Which physical memory range you are trying to add here and what is the node affinity? > ------------[ cut here ]------------ > kernel BUG at /Users/laurent/src/linux-ppc/mm/memory_hotplug.c:1084! > Oops: Exception in kernel mode, sig: 5 [#1] > LE PAGE_SIZE=3D64K MMU=3DHash SMP NR_CPUS=3D2048 NUMA pSeries > Modules linked in: rpadlpar_io rpaphp pseries_rng rng_core vmx_crypto g= f128mul binfmt_misc ip_tables x_tables xfs libcrc32c crc32c_vpmsum autofs= 4 > CPU: 8 PID: 10256 Comm: drmgr Not tainted 5.9.0-rc1+ #25 > NIP: c000000000403f34 LR: c000000000403f2c CTR: 0000000000000000 > REGS: c0000004876e3660 TRAP: 0700 Not tainted (5.9.0-rc1+) > MSR: 800000000282b033 CR: 24000448 = XER: 20040000 > CFAR: c000000000846d20 IRQMASK: 0 > GPR00: c000000000403f2c c0000004876e38f0 c0000000012f6f00 fffffffffffff= fef > GPR04: 0000000000000227 c0000004805ae680 0000000000000000 00000004886f0= 000 > GPR08: 0000000000000226 0000000000000003 0000000000000002 fffffffffffff= ffd > GPR12: 0000000088000484 c00000001ec96280 0000000000000000 0000000000000= 000 > GPR16: 0000000000000000 0000000000000000 0000000000000004 0000000000000= 003 > GPR20: c00000047814ffe0 c0000007ffff7c08 0000000000000010 c000000001333= 2c8 > GPR24: 0000000000000000 c0000000011f6cc0 0000000000000000 0000000000000= 000 > GPR28: ffffffffffffffef 0000000000000001 0000000150000000 0000000010000= 000 > NIP [c000000000403f34] add_memory_resource+0x244/0x340 > LR [c000000000403f2c] add_memory_resource+0x23c/0x340 > Call Trace: > [c0000004876e38f0] [c000000000403f2c] add_memory_resource+0x23c/0x340 (= unreliable) > [c0000004876e39c0] [c00000000040408c] __add_memory+0x5c/0xf0 > [c0000004876e39f0] [c0000000000e2b94] dlpar_add_lmb+0x1b4/0x500 > [c0000004876e3ad0] [c0000000000e3888] dlpar_memory+0x1f8/0xb80 > [c0000004876e3b60] [c0000000000dc0d0] handle_dlpar_errorlog+0xc0/0x190 > [c0000004876e3bd0] [c0000000000dc398] dlpar_store+0x198/0x4a0 > [c0000004876e3c90] [c00000000072e630] kobj_attr_store+0x30/0x50 > [c0000004876e3cb0] [c00000000051f954] sysfs_kf_write+0x64/0x90 > [c0000004876e3cd0] [c00000000051ee40] kernfs_fop_write+0x1b0/0x290 > [c0000004876e3d20] [c000000000438dd8] vfs_write+0xe8/0x290 > [c0000004876e3d70] [c0000000004391ac] ksys_write+0xdc/0x130 > [c0000004876e3dc0] [c000000000034e40] system_call_exception+0x160/0x270 > [c0000004876e3e20] [c00000000000d740] system_call_common+0xf0/0x27c > Instruction dump: > 48442e35 60000000 0b030000 3cbe0001 7fa3eb78 7bc48402 38a5fffe 7ca5fa14 > 78a58402 48442db1 60000000 7c7c1b78 <0b030000> 7f23cb78 4bda371d 600000= 00 > ---[ end trace 562fd6c109cd0fb2 ]--- The BUG_ON on failure is absolutely horrendous. There must be a better way to handle a failure like that. The failure means that sysfs_create_link_nowarn has failed. Please describe why that is the case. > This patch addresses the root cause by not relying on the system_state > value to detect whether the call is due to a hot-plug operation or not.= An > additional parameter is added to link_mem_sections() to tell the contex= t of > the call and this parameter is propagated to register_mem_sect_under_no= de() > throuugh the walk_memory_blocks()'s call. This looks like a hack to me and it deserves a better explanation. The existing code is a hack on its own and it is inconsistent with other boot time detection. We are using (system_state < SYSTEM_RUNNING) at othe= r places IIRC. Would it help to use the same here as well? Maybe we want to wrap that inside a helper (early_memory_init()) and use it at all places. > Fixes: 4fbce633910e ("mm/memory_hotplug.c: make register_mem_sect_under= _node() a callback of walk_memory_range()") > Signed-off-by: Laurent Dufour > Cc: stable@vger.kernel.org > Cc: Greg Kroah-Hartman > Cc: "Rafael J. Wysocki" > Cc: Andrew Morton > --- > drivers/base/node.c | 20 +++++++++++++++----- > include/linux/node.h | 6 +++--- > mm/memory_hotplug.c | 3 ++- > 3 files changed, 20 insertions(+), 9 deletions(-) >=20 > diff --git a/drivers/base/node.c b/drivers/base/node.c > index 508b80f6329b..27f828eeb531 100644 > --- a/drivers/base/node.c > +++ b/drivers/base/node.c > @@ -762,14 +762,19 @@ static int __ref get_nid_for_pfn(unsigned long pf= n) > } > =20 > /* register memory section under specified node if it spans that node = */ > +struct rmsun_args { > + int nid; > + bool hotadd; > +}; > static int register_mem_sect_under_node(struct memory_block *mem_blk, > - void *arg) > + void *args) > { > unsigned long memory_block_pfns =3D memory_block_size_bytes() / PAGE_= SIZE; > unsigned long start_pfn =3D section_nr_to_pfn(mem_blk->start_section_= nr); > unsigned long end_pfn =3D start_pfn + memory_block_pfns - 1; > - int ret, nid =3D *(int *)arg; > + int ret, nid =3D ((struct rmsun_args *)args)->nid; > unsigned long pfn; > + bool hotadd =3D ((struct rmsun_args *)args)->hotadd; > =20 > for (pfn =3D start_pfn; pfn <=3D end_pfn; pfn++) { > int page_nid; > @@ -789,7 +794,7 @@ static int register_mem_sect_under_node(struct memo= ry_block *mem_blk, > * case, during hotplug we know that all pages in the memory > * block belong to the same node. > */ > - if (system_state =3D=3D SYSTEM_BOOTING) { > + if (!hotadd) { > page_nid =3D get_nid_for_pfn(pfn); > if (page_nid < 0) > continue; > @@ -832,10 +837,15 @@ void unregister_memory_block_under_nodes(struct m= emory_block *mem_blk) > kobject_name(&node_devices[mem_blk->nid]->dev.kobj)); > } > =20 > -int link_mem_sections(int nid, unsigned long start_pfn, unsigned long = end_pfn) > +int link_mem_sections(int nid, unsigned long start_pfn, unsigned long = end_pfn, > + bool hotadd) > { > + struct rmsun_args args; > + > + args.nid =3D nid; > + args.hotadd =3D hotadd; > return walk_memory_blocks(PFN_PHYS(start_pfn), > - PFN_PHYS(end_pfn - start_pfn), (void *)&nid, > + PFN_PHYS(end_pfn - start_pfn), (void *)&args, > register_mem_sect_under_node); > } > =20 > diff --git a/include/linux/node.h b/include/linux/node.h > index 4866f32a02d8..6df9a4548650 100644 > --- a/include/linux/node.h > +++ b/include/linux/node.h > @@ -100,10 +100,10 @@ typedef void (*node_registration_func_t)(struct = node *); > =20 > #if defined(CONFIG_MEMORY_HOTPLUG_SPARSE) && defined(CONFIG_NUMA) > extern int link_mem_sections(int nid, unsigned long start_pfn, > - unsigned long end_pfn); > + unsigned long end_pfn, bool hotadd); > #else > static inline int link_mem_sections(int nid, unsigned long start_pfn, > - unsigned long end_pfn) > + unsigned long end_pfn, bool hotadd) > { > return 0; > } > @@ -128,7 +128,7 @@ static inline int register_one_node(int nid) > if (error) > return error; > /* link memory sections under this node */ > - error =3D link_mem_sections(nid, start_pfn, end_pfn); > + error =3D link_mem_sections(nid, start_pfn, end_pfn, false); > } > =20 > return error; > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index e9d5ab5d3ca0..28028db8364a 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1080,7 +1080,8 @@ int __ref add_memory_resource(int nid, struct res= ource *res) > } > =20 > /* link memory sections under this node.*/ > - ret =3D link_mem_sections(nid, PFN_DOWN(start), PFN_UP(start + size -= 1)); > + ret =3D link_mem_sections(nid, PFN_DOWN(start), PFN_UP(start + size -= 1), > + true); > BUG_ON(ret); > =20 > /* create new memmap entry */ > --=20 > 2.28.0 --=20 Michal Hocko SUSE Labs