linux.git, branch v5.4.70 Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git Linux 5.4.70 2020-10-07T06:01:31+00:00 Greg Kroah-Hartman gregkh@linuxfoundation.org 2020-10-07T06:01:31+00:00 d22f99d235e13356521b374410a6ee24f50b65e6 Tested-by: Jon Hunter <jonathanh@nvidia.com> Tested-by: Shuah Khan <skhan@linuxfoundation.org> Tested-by: Linux Kernel Functional Testing <lkft@linaro.org> Tested-by: Guenter Roeck <linux@roeck-us.net> Link: https://lore.kernel.org/r/20201005142109.796046410@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Shuah Khan <skhan@linuxfoundation.org>
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20201005142109.796046410@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
netfilter: ctnetlink: add a range check for l3/l4 protonum 2020-10-07T06:01:31+00:00 Will McVicker willmcvicker@google.com 2020-08-24T19:38:32+00:00 253052b636e98083b1ecc3e9b0cf6f151e1cb8c6 commit 1cc5ef91d2ff94d2bf2de3b3585423e8a1051cb6 upstream. The indexes to the nf_nat_l[34]protos arrays come from userspace. So check the tuple's family, e.g. l3num, when creating the conntrack in order to prevent an OOB memory access during setup. Here is an example kernel panic on 4.14.180 when userspace passes in an index greater than NFPROTO_NUMPROTO. Internal error: Oops - BUG: 0 [#1] PREEMPT SMP Modules linked in:... Process poc (pid: 5614, stack limit = 0x00000000a3933121) CPU: 4 PID: 5614 Comm: poc Tainted: G S W O 4.14.180-g051355490483 Hardware name: Qualcomm Technologies, Inc. SM8150 V2 PM8150 Google Inc. MSM task: 000000002a3dfffe task.stack: 00000000a3933121 pc : __cfi_check_fail+0x1c/0x24 lr : __cfi_check_fail+0x1c/0x24 ... Call trace: __cfi_check_fail+0x1c/0x24 name_to_dev_t+0x0/0x468 nfnetlink_parse_nat_setup+0x234/0x258 ctnetlink_parse_nat_setup+0x4c/0x228 ctnetlink_new_conntrack+0x590/0xc40 nfnetlink_rcv_msg+0x31c/0x4d4 netlink_rcv_skb+0x100/0x184 nfnetlink_rcv+0xf4/0x180 netlink_unicast+0x360/0x770 netlink_sendmsg+0x5a0/0x6a4 ___sys_sendmsg+0x314/0x46c SyS_sendmsg+0xb4/0x108 el0_svc_naked+0x34/0x38 This crash is not happening since 5.4+, however, ctnetlink still allows for creating entries with unsupported layer 3 protocol number. Fixes: c1d10adb4a521 ("[NETFILTER]: Add ctnetlink port for nf_conntrack") Signed-off-by: Will McVicker <willmcvicker@google.com> [pablo@netfilter.org: rebased original patch on top of nf.git] Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 1cc5ef91d2ff94d2bf2de3b3585423e8a1051cb6 upstream.

The indexes to the nf_nat_l[34]protos arrays come from userspace. So
check the tuple's family, e.g. l3num, when creating the conntrack in
order to prevent an OOB memory access during setup.  Here is an example
kernel panic on 4.14.180 when userspace passes in an index greater than
NFPROTO_NUMPROTO.

Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
Modules linked in:...
Process poc (pid: 5614, stack limit = 0x00000000a3933121)
CPU: 4 PID: 5614 Comm: poc Tainted: G S      W  O    4.14.180-g051355490483
Hardware name: Qualcomm Technologies, Inc. SM8150 V2 PM8150 Google Inc. MSM
task: 000000002a3dfffe task.stack: 00000000a3933121
pc : __cfi_check_fail+0x1c/0x24
lr : __cfi_check_fail+0x1c/0x24
...
Call trace:
__cfi_check_fail+0x1c/0x24
name_to_dev_t+0x0/0x468
nfnetlink_parse_nat_setup+0x234/0x258
ctnetlink_parse_nat_setup+0x4c/0x228
ctnetlink_new_conntrack+0x590/0xc40
nfnetlink_rcv_msg+0x31c/0x4d4
netlink_rcv_skb+0x100/0x184
nfnetlink_rcv+0xf4/0x180
netlink_unicast+0x360/0x770
netlink_sendmsg+0x5a0/0x6a4
___sys_sendmsg+0x314/0x46c
SyS_sendmsg+0xb4/0x108
el0_svc_naked+0x34/0x38

This crash is not happening since 5.4+, however, ctnetlink still
allows for creating entries with unsupported layer 3 protocol number.

Fixes: c1d10adb4a521 ("[NETFILTER]: Add ctnetlink port for nf_conntrack")
Signed-off-by: Will McVicker <willmcvicker@google.com>
[pablo@netfilter.org: rebased original patch on top of nf.git]
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ep_create_wakeup_source(): dentry name can change under you... 2020-10-07T06:01:31+00:00 Al Viro viro@zeniv.linux.org.uk 2020-09-24T23:41:58+00:00 27423bb05e251020660e092c2f6b78ad2e4cb9a3 commit 3701cb59d892b88d569427586f01491552f377b1 upstream. or get freed, for that matter, if it's a long (separately stored) name. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 3701cb59d892b88d569427586f01491552f377b1 upstream.

or get freed, for that matter, if it's a long (separately stored)
name.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
epoll: EPOLL_CTL_ADD: close the race in decision to take fast path 2020-10-07T06:01:30+00:00 Al Viro viro@zeniv.linux.org.uk 2020-09-10T12:33:27+00:00 8e58bad666bb11432201d0c6020cffc73780bdd0 commit fe0a916c1eae8e17e86c3753d13919177d63ed7e upstream. Checking for the lack of epitems refering to the epoll we want to insert into is not enough; we might have an insertion of that epoll into another one that has already collected the set of files to recheck for excessive reverse paths, but hasn't gotten to creating/inserting the epitem for it. However, any such insertion in progress can be detected - it will update the generation count in our epoll when it's done looking through it for files to check. That gets done under ->mtx of our epoll and that allows us to detect that safely. We are *not* holding epmutex here, so the generation count is not stable. However, since both the update of ep->gen by loop check and (later) insertion into ->f_ep_link are done with ep->mtx held, we are fine - the sequence is grab epmutex bump loop_check_gen ... grab tep->mtx // 1 tep->gen = loop_check_gen ... drop tep->mtx // 2 ... grab tep->mtx // 3 ... insert into ->f_ep_link ... drop tep->mtx // 4 bump loop_check_gen drop epmutex and if the fastpath check in another thread happens for that eventpoll, it can come * before (1) - in that case fastpath is just fine * after (4) - we'll see non-empty ->f_ep_link, slow path taken * between (2) and (3) - loop_check_gen is stable, with ->mtx providing barriers and we end up taking slow path. Note that ->f_ep_link emptiness check is slightly racy - we are protected against insertions into that list, but removals can happen right under us. Not a problem - in the worst case we'll end up taking a slow path for no good reason. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit fe0a916c1eae8e17e86c3753d13919177d63ed7e upstream.

Checking for the lack of epitems refering to the epoll we want to insert into
is not enough; we might have an insertion of that epoll into another one that
has already collected the set of files to recheck for excessive reverse paths,
but hasn't gotten to creating/inserting the epitem for it.

However, any such insertion in progress can be detected - it will update the
generation count in our epoll when it's done looking through it for files
to check.  That gets done under ->mtx of our epoll and that allows us to
detect that safely.

We are *not* holding epmutex here, so the generation count is not stable.
However, since both the update of ep->gen by loop check and (later)
insertion into ->f_ep_link are done with ep->mtx held, we are fine -
the sequence is
	grab epmutex
	bump loop_check_gen
	...
	grab tep->mtx		// 1
	tep->gen = loop_check_gen
	...
	drop tep->mtx		// 2
	...
	grab tep->mtx		// 3
	...
	insert into ->f_ep_link
	...
	drop tep->mtx		// 4
	bump loop_check_gen
	drop epmutex
and if the fastpath check in another thread happens for that
eventpoll, it can come
	* before (1) - in that case fastpath is just fine
	* after (4) - we'll see non-empty ->f_ep_link, slow path
taken
	* between (2) and (3) - loop_check_gen is stable,
with ->mtx providing barriers and we end up taking slow path.

Note that ->f_ep_link emptiness check is slightly racy - we are protected
against insertions into that list, but removals can happen right under us.
Not a problem - in the worst case we'll end up taking a slow path for
no good reason.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
epoll: replace ->visited/visited_list with generation count 2020-10-07T06:01:30+00:00 Al Viro viro@zeniv.linux.org.uk 2020-09-10T12:30:05+00:00 099b7a1bc7910baefdb7d2341a9199c9c92aaecb commit 18306c404abe18a0972587a6266830583c60c928 upstream. removes the need to clear it, along with the races. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 18306c404abe18a0972587a6266830583c60c928 upstream.

removes the need to clear it, along with the races.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
epoll: do not insert into poll queues until all sanity checks are done 2020-10-07T06:01:30+00:00 Al Viro viro@zeniv.linux.org.uk 2020-09-10T02:25:06+00:00 8993da3d4d3a7ae721e9dafa140ba64c0e632a50 commit f8d4f44df056c5b504b0d49683fb7279218fd207 upstream. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit f8d4f44df056c5b504b0d49683fb7279218fd207 upstream.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
nvme: consolidate chunk_sectors settings 2020-10-07T06:01:30+00:00 Keith Busch kbusch@kernel.org 2020-04-09T16:09:06+00:00 8db44b30d392b03df5e0dfab02dbafc591ec1320 commit 38adf94e166e3cb4eb89683458ca578051e8218d upstream. Move the quirked chunk_sectors setting to the same location as noiob so one place registers this setting. And since the noiob value is only used locally, remove the member from struct nvme_ns. Signed-off-by: Keith Busch <kbusch@kernel.org> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Revanth Rajashekar <revanth.rajashekar@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 38adf94e166e3cb4eb89683458ca578051e8218d upstream.

Move the quirked chunk_sectors setting to the same location as noiob so
one place registers this setting. And since the noiob value is only used
locally, remove the member from struct nvme_ns.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Revanth Rajashekar <revanth.rajashekar@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
nvme: Introduce nvme_lba_to_sect() 2020-10-07T06:01:30+00:00 Damien Le Moal damien.lemoal@wdc.com 2019-10-21T03:40:04+00:00 03f4f85bbd7dc2bb9ebb5e96937bbf778d89b586 commit e08f2ae850929d40e66268ee47e443e7ea56eeb7 upstream. Introduce the new helper function nvme_lba_to_sect() to convert a device logical block number to a 512B sector number. Use this new helper in obvious places, cleaning up the code. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Keith Busch <kbusch@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Revanth Rajashekar <revanth.rajashekar@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit e08f2ae850929d40e66268ee47e443e7ea56eeb7 upstream.

Introduce the new helper function nvme_lba_to_sect() to convert a device
logical block number to a 512B sector number. Use this new helper in
obvious places, cleaning up the code.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Revanth Rajashekar <revanth.rajashekar@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
nvme: Cleanup and rename nvme_block_nr() 2020-10-07T06:01:30+00:00 Damien Le Moal damien.lemoal@wdc.com 2019-10-21T03:40:03+00:00 34b939695f2852ff39ecb1c6b6abbcc7c13c3a12 commit 314d48dd224897e35ddcaf5a1d7d133b5adddeb7 upstream. Rename nvme_block_nr() to nvme_sect_to_lba() and use SECTOR_SHIFT instead of its hard coded value 9. Also add a comment to decribe this helper. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Keith Busch <kbusch@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Revanth Rajashekar <revanth.rajashekar@intel.com>1 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 314d48dd224897e35ddcaf5a1d7d133b5adddeb7 upstream.

Rename nvme_block_nr() to nvme_sect_to_lba() and use SECTOR_SHIFT
instead of its hard coded value 9. Also add a comment to decribe this
helper.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Revanth Rajashekar <revanth.rajashekar@intel.com>1
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mm: don't rely on system state to detect hot-plug operations 2020-10-07T06:01:30+00:00 Laurent Dufour ldufour@linux.ibm.com 2020-09-26T04:19:31+00:00 9626c1a63703c08e6c17adceb0d4cd468fc7ce14 commit f85086f95fa36194eb0db5cd5c12e56801b98523 upstream. In register_mem_sect_under_node() the system_state's value is checked to detect whether the call is made during boot time or during 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 state by the ACPI [1]. So checking against the system state is not enough. The consequence is that on system with interleaved node's ranges like this: 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] 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 ranges 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: $ 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 In that case, the system is able to boot but if later one of theses memory blocks is hot-unplugged and then hot-plugged, the sysfs inconsistency is detected and this is triggering a BUG_ON(): kernel BUG at /Users/laurent/src/linux-ppc/mm/memory_hotplug.c:1084! Oops: Exception in kernel mode, sig: 5 [#1] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries Modules linked in: rpadlpar_io rpaphp pseries_rng rng_core vmx_crypto gf128mul binfmt_misc ip_tables x_tables xfs libcrc32c crc32c_vpmsum autofs4 CPU: 8 PID: 10256 Comm: drmgr Not tainted 5.9.0-rc1+ #25 Call Trace: add_memory_resource+0x23c/0x340 (unreliable) __add_memory+0x5c/0xf0 dlpar_add_lmb+0x1b4/0x500 dlpar_memory+0x1f8/0xb80 handle_dlpar_errorlog+0xc0/0x190 dlpar_store+0x198/0x4a0 kobj_attr_store+0x30/0x50 sysfs_kf_write+0x64/0x90 kernfs_fop_write+0x1b0/0x290 vfs_write+0xe8/0x290 ksys_write+0xdc/0x130 system_call_exception+0x160/0x270 system_call_common+0xf0/0x27c 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 extra parameter is added to link_mem_sections() detailing whether the operation is due to a hot-plug operation. [1] According to Oscar Salvador, using this qemu command line, ACPI memory hotplug operations are raised at SYSTEM_SCHEDULING state: $QEMU -enable-kvm -machine pc -smp 4,sockets=4,cores=1,threads=1 -cpu host -monitor pty \ -m size=$MEM,slots=255,maxmem=4294967296k \ -numa node,nodeid=0,cpus=0-3,mem=512 -numa node,nodeid=1,mem=512 \ -object memory-backend-ram,id=memdimm0,size=134217728 -device pc-dimm,node=0,memdev=memdimm0,id=dimm0,slot=0 \ -object memory-backend-ram,id=memdimm1,size=134217728 -device pc-dimm,node=0,memdev=memdimm1,id=dimm1,slot=1 \ -object memory-backend-ram,id=memdimm2,size=134217728 -device pc-dimm,node=0,memdev=memdimm2,id=dimm2,slot=2 \ -object memory-backend-ram,id=memdimm3,size=134217728 -device pc-dimm,node=0,memdev=memdimm3,id=dimm3,slot=3 \ -object memory-backend-ram,id=memdimm4,size=134217728 -device pc-dimm,node=1,memdev=memdimm4,id=dimm4,slot=4 \ -object memory-backend-ram,id=memdimm5,size=134217728 -device pc-dimm,node=1,memdev=memdimm5,id=dimm5,slot=5 \ -object memory-backend-ram,id=memdimm6,size=134217728 -device pc-dimm,node=1,memdev=memdimm6,id=dimm6,slot=6 \ Fixes: 4fbce633910e ("mm/memory_hotplug.c: make register_mem_sect_under_node() a callback of walk_memory_range()") Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Nathan Lynch <nathanl@linux.ibm.com> Cc: Scott Cheloha <cheloha@linux.ibm.com> Cc: Tony Luck <tony.luck@intel.com> Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/20200915094143.79181-3-ldufour@linux.ibm.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit f85086f95fa36194eb0db5cd5c12e56801b98523 upstream.

In register_mem_sect_under_node() the system_state's value is checked to
detect whether the call is made during boot time or during 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
state by the ACPI [1].  So checking against the system state is not
enough.

The consequence is that on system with interleaved node's ranges like this:

 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]

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
ranges 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:

  $ 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

In that case, the system is able to boot but if later one of theses
memory blocks is hot-unplugged and then hot-plugged, the sysfs
inconsistency is detected and this is triggering a BUG_ON():

  kernel BUG at /Users/laurent/src/linux-ppc/mm/memory_hotplug.c:1084!
  Oops: Exception in kernel mode, sig: 5 [#1]
  LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
  Modules linked in: rpadlpar_io rpaphp pseries_rng rng_core vmx_crypto gf128mul binfmt_misc ip_tables x_tables xfs libcrc32c crc32c_vpmsum autofs4
  CPU: 8 PID: 10256 Comm: drmgr Not tainted 5.9.0-rc1+ #25
  Call Trace:
    add_memory_resource+0x23c/0x340 (unreliable)
    __add_memory+0x5c/0xf0
    dlpar_add_lmb+0x1b4/0x500
    dlpar_memory+0x1f8/0xb80
    handle_dlpar_errorlog+0xc0/0x190
    dlpar_store+0x198/0x4a0
    kobj_attr_store+0x30/0x50
    sysfs_kf_write+0x64/0x90
    kernfs_fop_write+0x1b0/0x290
    vfs_write+0xe8/0x290
    ksys_write+0xdc/0x130
    system_call_exception+0x160/0x270
    system_call_common+0xf0/0x27c

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
extra parameter is added to link_mem_sections() detailing whether the
operation is due to a hot-plug operation.

[1] According to Oscar Salvador, using this qemu command line, ACPI
memory hotplug operations are raised at SYSTEM_SCHEDULING state:

  $QEMU -enable-kvm -machine pc -smp 4,sockets=4,cores=1,threads=1 -cpu host -monitor pty \
        -m size=$MEM,slots=255,maxmem=4294967296k  \
        -numa node,nodeid=0,cpus=0-3,mem=512 -numa node,nodeid=1,mem=512 \
        -object memory-backend-ram,id=memdimm0,size=134217728 -device pc-dimm,node=0,memdev=memdimm0,id=dimm0,slot=0 \
        -object memory-backend-ram,id=memdimm1,size=134217728 -device pc-dimm,node=0,memdev=memdimm1,id=dimm1,slot=1 \
        -object memory-backend-ram,id=memdimm2,size=134217728 -device pc-dimm,node=0,memdev=memdimm2,id=dimm2,slot=2 \
        -object memory-backend-ram,id=memdimm3,size=134217728 -device pc-dimm,node=0,memdev=memdimm3,id=dimm3,slot=3 \
        -object memory-backend-ram,id=memdimm4,size=134217728 -device pc-dimm,node=1,memdev=memdimm4,id=dimm4,slot=4 \
        -object memory-backend-ram,id=memdimm5,size=134217728 -device pc-dimm,node=1,memdev=memdimm5,id=dimm5,slot=5 \
        -object memory-backend-ram,id=memdimm6,size=134217728 -device pc-dimm,node=1,memdev=memdimm6,id=dimm6,slot=6 \

Fixes: 4fbce633910e ("mm/memory_hotplug.c: make register_mem_sect_under_node() a callback of walk_memory_range()")
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200915094143.79181-3-ldufour@linux.ibm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>