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=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 870ABC433E2 for ; Mon, 14 Sep 2020 08:55:48 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 14FE02076C for ; Mon, 14 Sep 2020 08:55:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 14FE02076C 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 4E12D6B0003; Mon, 14 Sep 2020 04:55:47 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 46BCC6B0037; Mon, 14 Sep 2020 04:55:47 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 30C846B0055; Mon, 14 Sep 2020 04:55:47 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0142.hostedemail.com [216.40.44.142]) by kanga.kvack.org (Postfix) with ESMTP id 148156B0003 for ; Mon, 14 Sep 2020 04:55:47 -0400 (EDT) Received: from smtpin12.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id B254D5DE5 for ; Mon, 14 Sep 2020 08:55:46 +0000 (UTC) X-FDA: 77261059092.12.join11_221525a27107 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin12.hostedemail.com (Postfix) with ESMTP id 7F37B1800707D for ; Mon, 14 Sep 2020 08:55:46 +0000 (UTC) X-HE-Tag: join11_221525a27107 X-Filterd-Recvd-Size: 10800 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf18.hostedemail.com (Postfix) with ESMTP for ; Mon, 14 Sep 2020 08:55:45 +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 3FE06AFE1; Mon, 14 Sep 2020 08:56:00 +0000 (UTC) Date: Mon, 14 Sep 2020 10:55:44 +0200 From: Michal Hocko To: Laurent Dufour Cc: akpm@linux-foundation.org, David Hildenbrand , Oscar Salvador , Greg Kroah-Hartman , linux-mm@kvack.org, "Rafael J . Wysocki" , nathanl@linux.ibm.com, cheloha@linux.ibm.com, Tony Luck , Fenghua Yu , linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 2/3] mm: don't rely on system state to detect hot-plug operations Message-ID: <20200914085544.GB16999@dhcp22.suse.cz> References: <20200911134831.53258-1-ldufour@linux.ibm.com> <20200911134831.53258-3-ldufour@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200911134831.53258-3-ldufour@linux.ibm.com> X-Rspamd-Queue-Id: 7F37B1800707D X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 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: On Fri 11-09-20 15:48:30, 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 against SYSTEM_BOOTING is > wrong because regular memory is registered at SYSTEM_SCHEDULING state. = In > addition memory hot-plug operation can be triggered at this system stat= e > too by the ACPI. Please add (an example would be Qemu to replay hot added memory after reboot). > So checking against the system state is not enough. >=20 > The consequence is that on system with interleaved node's ranges like t= his: > Early memory node ranges > node 1: [mem 0x0000000000000000-0x000000011fffffff] > node 2: [mem 0x0000000120000000-0x000000014fffffff] > node 1: [mem 0x0000000150000000-0x00000001ffffffff] > node 0: [mem 0x0000000200000000-0x000000048fffffff] > node 2: [mem 0x0000000490000000-0x00000007ffffffff] >=20 > 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 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 to multiple nodes= : >=20 > $ ls -l /sys/devices/system/memory/memory21/node* > total 0 > lrwxrwxrwx 1 root root 0 Aug 24 05:27 node1 -> ../../node/node1 > lrwxrwxrwx 1 root root 0 Aug 24 05:27 node2 -> ../../node/node2 >=20 > In that case, the system is able to boot but if later one of theses mem= ory > block is hot-unplugged and then hot-plugged, the sysfs inconsistency is > detected and triggered a BUG_ON(): >=20 > ------------[ 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 ]--- >=20 > 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. An ext= ra > parameter is needed in register_mem_sect_under_node() detailing whether= the > operation is due to a hot-plug operation. Thanks this description is much more clear! > 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 > Cc: Michal Hocko > Cc: David Hildenbrand Wrt to the specific implementation I cannot say I would care much. Duplicating the code will make the two callers simpler but there will be a code duplication. We have that weird intermix for hotplug vs. early init at other places. So I would be very lightly prefering this patch and do a larger cleanup on top of that. It is at least clear what the patch does this way. So Acked-by: Michal Hocko > --- > drivers/base/node.c | 21 ++++++++++++++++----- > include/linux/node.h | 9 ++++++--- > mm/memory_hotplug.c | 3 ++- > 3 files changed, 24 insertions(+), 9 deletions(-) >=20 > diff --git a/drivers/base/node.c b/drivers/base/node.c > index 508b80f6329b..862516c5a5ae 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; > + enum memplug_context context; > +}; > 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; > + enum memplug_context context =3D ((struct rmsun_args *)args)->context= ; > =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 (context =3D=3D MEMPLUG_EARLY) { > page_nid =3D get_nid_for_pfn(pfn); > if (page_nid < 0) > continue; > @@ -832,10 +837,16 @@ 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, > + enum memplug_context context) > { > + struct rmsun_args args =3D { > + .nid =3D nid, > + .context =3D context, > + }; > + > 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..8ff08520488c 100644 > --- a/include/linux/node.h > +++ b/include/linux/node.h > @@ -100,10 +100,12 @@ 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, > + enum memplug_context context); > #else > static inline int link_mem_sections(int nid, unsigned long start_pfn, > - unsigned long end_pfn) > + unsigned long end_pfn, > + enum memplug_context context) > { > return 0; > } > @@ -128,7 +130,8 @@ 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, > + MEMPLUG_EARLY); > } > =20 > return error; > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index fc21625e42de..912d355ca446 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), > + MEMPLUG_HOTPLUG); > BUG_ON(ret); > =20 > /* create new memmap entry */ > --=20 > 2.28.0 --=20 Michal Hocko SUSE Labs