After a LPM, the device tree node ibm,dynamic-reconfiguration-memory may be
updated by the hypervisor in the case the NUMA topology of the LPAR's
memory is updated.
This is handled by the kernel, but the memory's node is not updated because
there is no way to move a memory block between nodes from the Linux kernel
point of view.
If later a memory block is added or removed, drmem_update_dt() is called
and it is overwriting the DT node ibm,dynamic-reconfiguration-memory to
match the added or removed LMB. But the LMB's associativity node has not
been updated after the DT node update and thus the node is overwritten by
the Linux's topology instead of the hypervisor one.
Introduce a hook called when the ibm,dynamic-reconfiguration-memory node is
updated to force an update of the LMB's associativity. However, ignore the
call to that hook when the update has been triggered by drmem_update_dt().
Because, in that case, the LMB tree has been used to set the DT property
and thus it doesn't need to be updated back. Since drmem_update_dt() is
called under the protection of the device_hotplug_lock and the hook is
called in the same context, use a simple boolean variable to detect that
call.
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Reviewed-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210517090606.56930-1-ldufour@linux.ibm.com
At memory hot-remove time we can retrieve an LMB's nid from its
corresponding memory_block. There is no need to store the nid
in multiple locations.
Note that lmb_to_memblock() uses find_memory_block() to get the
corresponding memory_block. As find_memory_block() runs in sub-linear
time this approach is negligibly slower than what we do at present.
In exchange for this lookup at hot-remove time we no longer need to
call memory_add_physaddr_to_nid() during drmem_init() for each LMB.
On powerpc, memory_add_physaddr_to_nid() is a linear search, so this
spares us an O(n^2) initialization during boot.
On systems with many LMBs that initialization overhead is palpable and
disruptive. For example, on a box with 249854 LMBs we're seeing
drmem_init() take upwards of 30 seconds to complete:
[ 53.721639] drmem: initializing drmem v2
[ 80.604346] watchdog: BUG: soft lockup - CPU#65 stuck for 23s! [swapper/0:1]
[ 80.604377] Modules linked in:
[ 80.604389] CPU: 65 PID: 1 Comm: swapper/0 Not tainted 5.6.0-rc2+ #4
[ 80.604397] NIP: c0000000000a4980 LR: c0000000000a4940 CTR: 0000000000000000
[ 80.604407] REGS: c0002dbff8493830 TRAP: 0901 Not tainted (5.6.0-rc2+)
[ 80.604412] MSR: 8000000002009033 <SF,VEC,EE,ME,IR,DR,RI,LE> CR: 44000248 XER: 0000000d
[ 80.604431] CFAR: c0000000000a4a38 IRQMASK: 0
[ 80.604431] GPR00: c0000000000a4940 c0002dbff8493ac0 c000000001904400 c0003cfffffede30
[ 80.604431] GPR04: 0000000000000000 c000000000f4095a 000000000000002f 0000000010000000
[ 80.604431] GPR08: c0000bf7ecdb7fb8 c0000bf7ecc2d3c8 0000000000000008 c00c0002fdfb2001
[ 80.604431] GPR12: 0000000000000000 c00000001e8ec200
[ 80.604477] NIP [c0000000000a4980] hot_add_scn_to_nid+0xa0/0x3e0
[ 80.604486] LR [c0000000000a4940] hot_add_scn_to_nid+0x60/0x3e0
[ 80.604492] Call Trace:
[ 80.604498] [c0002dbff8493ac0] [c0000000000a4940] hot_add_scn_to_nid+0x60/0x3e0 (unreliable)
[ 80.604509] [c0002dbff8493b20] [c000000000087c10] memory_add_physaddr_to_nid+0x20/0x60
[ 80.604521] [c0002dbff8493b40] [c0000000010d4880] drmem_init+0x25c/0x2f0
[ 80.604530] [c0002dbff8493c10] [c000000000010154] do_one_initcall+0x64/0x2c0
[ 80.604540] [c0002dbff8493ce0] [c0000000010c4aa0] kernel_init_freeable+0x2d8/0x3a0
[ 80.604550] [c0002dbff8493db0] [c000000000010824] kernel_init+0x2c/0x148
[ 80.604560] [c0002dbff8493e20] [c00000000000b648] ret_from_kernel_thread+0x5c/0x74
[ 80.604567] Instruction dump:
[ 80.604574] 392918e8 e9490000 e90a000a e92a0000 80ea000c 1d080018 3908ffe8 7d094214
[ 80.604586] 7fa94040 419d00dc e9490010 714a0088 <2faa0008> 409e00ac e9490000 7fbe5040
[ 89.047390] drmem: 249854 LMB(s)
With a patched kernel on the same machine we're no longer seeing the
soft lockup. drmem_init() now completes in negligible time, even when
the LMB count is large.
Fixes: b2d3b5ee66 ("powerpc/pseries: Track LMB nid instead of using device tree")
Signed-off-by: Scott Cheloha <cheloha@linux.ibm.com>
Reviewed-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200811015115.63677-1-cheloha@linux.ibm.com
Currently, numa & prom are the only users of drmem LMB walk code.
Loading kdump with kexec_file also needs to walk the drmem LMBs to
setup the usable memory ranges for kdump kernel. But there are couple
of issues in using the code as is. One, walk_drmem_lmb() code is built
into the .init section currently, while kexec_file needs it later.
Two, there is no scope to pass data to the callback function for
processing and/or erroring out on certain conditions.
Fix that by, moving drmem LMB walk code out of .init section, adding
scope to pass data to the callback function and bailing out when an
error is encountered in the callback function.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Tested-by: Pingfan Liu <piliu@redhat.com>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/159602282727.575379.3979857013827701828.stgit@hbathini
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 3029 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When removing memory we need to remove the memory from the node
it was added to instead of looking up the node it should be in
in the device tree.
During testing we have seen scenarios where the affinity for a
LMB changes due to a partition migration or PRRN event. In these
cases the node the LMB exists in may not match the node the device
tree indicates it belongs in. This can lead to a system crash
when trying to DLPAR remove the LMB after a migration or PRRN
event. The current code looks up the node in the device tree to
remove the LMB from, the crash occurs when we try to offline this
node and it does not have any data, i.e. node_data[nid] == NULL.
36:mon> e
cpu 0x36: Vector: 300 (Data Access) at [c0000001828b7810]
pc: c00000000036d08c: try_offline_node+0x2c/0x1b0
lr: c0000000003a14ec: remove_memory+0xbc/0x110
sp: c0000001828b7a90
msr: 800000000280b033
dar: 9a28
dsisr: 40000000
current = 0xc0000006329c4c80
paca = 0xc000000007a55200 softe: 0 irq_happened: 0x01
pid = 76926, comm = kworker/u320:3
36:mon> t
[link register ] c0000000003a14ec remove_memory+0xbc/0x110
[c0000001828b7a90] c00000000006a1cc arch_remove_memory+0x9c/0xd0 (unreliable)
[c0000001828b7ad0] c0000000003a14e0 remove_memory+0xb0/0x110
[c0000001828b7b20] c0000000000c7db4 dlpar_remove_lmb+0x94/0x160
[c0000001828b7b60] c0000000000c8ef8 dlpar_memory+0x7e8/0xd10
[c0000001828b7bf0] c0000000000bf828 handle_dlpar_errorlog+0xf8/0x160
[c0000001828b7c60] c0000000000bf8cc pseries_hp_work_fn+0x3c/0xa0
[c0000001828b7c90] c000000000128cd8 process_one_work+0x298/0x5a0
[c0000001828b7d20] c000000000129068 worker_thread+0x88/0x620
[c0000001828b7dc0] c00000000013223c kthread+0x1ac/0x1c0
[c0000001828b7e30] c00000000000b45c ret_from_kernel_thread+0x5c/0x80
To resolve this we need to track the node a LMB belongs to when
it is added to the system so we can remove it from that node instead
of the node that the device tree indicates it should belong to.
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Memory addtion and removal by count and indexed-count methods
temporarily mark the LMBs that are being added/removed by a special
flag value DRMEM_LMB_RESERVED. Accessing flags value directly at a few
places without proper accessor method is causing two unexpected
side-effects:
- DRMEM_LMB_RESERVED bit is becoming part of the flags word of
drconf_cell_v2 entries in ibm,dynamic-memory-v2 DT property.
- This results in extra drconf_cell entries in ibm,dynamic-memory-v2.
For example if 1G memory is added, it leads to one entry for 3 LMBs
and 1 separate entry for the last LMB. All the 4 LMBs should be
defined by one entry here.
Fix this by always accessing the flags by its accessor method
drmem_lmb_flags().
Fixes: 2b31e3aec1 ("powerpc/drmem: Add support for ibm, dynamic-memory-v2 property")
Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Reviewed-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Some versions of QEMU will produce an ibm,dynamic-reconfiguration-memory
node with a ibm,dynamic-memory property that is zero-filled. This
causes the drmem code to oops trying to parse this property.
The fix for this is to validate that the property does contain LMB
entries before trying to parse it and bail if the count is zero.
Oops: Kernel access of bad area, sig: 11 [#1]
DAR: 0000000000000010
NIP read_drconf_v1_cell+0x54/0x9c
LR read_drconf_v1_cell+0x48/0x9c
Call Trace:
__param_initcall_debug+0x0/0x28 (unreliable)
drmem_init+0x144/0x2f8
do_one_initcall+0x64/0x1d0
kernel_init_freeable+0x298/0x38c
kernel_init+0x24/0x160
ret_from_kernel_thread+0x5c/0xb4
The ibm,dynamic-reconfiguration-memory device tree property generated
that causes this:
ibm,dynamic-reconfiguration-memory {
ibm,lmb-size = <0x0 0x10000000>;
ibm,memory-flags-mask = <0xff>;
ibm,dynamic-memory = <0x0 0x0 0x0 0x0 0x0 0x0>;
linux,phandle = <0x7e57eed8>;
ibm,associativity-lookup-arrays = <0x1 0x4 0x0 0x0 0x0 0x0>;
ibm,memory-preservation-time = <0x0>;
};
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Reviewed-by: Cyril Bur <cyrilbur@gmail.com>
Tested-by: Daniel Black <daniel@linux.vnet.ibm.com>
[mpe: Trim oops report]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The Power Hypervisor has introduced a new device tree format for
the property describing the dynamic reconfiguration LMBs for a system,
ibm,dynamic-memory-v2. This new format condenses the size of the
property, especially on large memory systems, by reporting sets
of LMBs that have the same properties (flags and associativity array
index).
This patch updates the powerpc/mm/drmem.c code to provide routines
that can parse the new device tree format during the walk_drmem_lmb*
routines used during boot, the creation of the LMB array, and updating
the device tree to create a new property in the proper format for
ibm,dynamic-memory-v2.
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Now that the powerpc code parses dynamic reconfiguration memory
LMB information from the LMB array and not the device tree
directly we can move the of_drconf_cell struct to drmem.h where
it fits better.
In addition, the struct is renamed to of_drconf_cell_v1 in
anticipation of upcoming support for version 2 of the dynamic
reconfiguration property and the members are typed as __be*
values to reflect how they exist in the device tree.
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Update the pseries memory hotplug code to use the newly added
dynamic reconfiguration LMB array. Doing this is required for the
upcoming support of version 2 of the dynamic reconfiguration
device tree property.
In addition, making this change cleans up the code that parses the
LMB information as we no longer need to worry about device tree
format. This allows us to discard one of the first steps on memory
hotplug where we make a working copy of the device tree property and
convert the entire property to cpu format. Instead we just use the
LMB array directly while holding the memory hotplug lock.
This patch also moves the updating of the device tree property to
powerpc/mm/drmem.c. This allows to the hotplug code to work without
needing to know the device tree format and provides a single
routine for updating the device tree property. This new routine
will handle determination of the proper device tree format and
generate a properly formatted device tree property.
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Update code in powerpc/numa.c to use the walk_drmem_lmbs()
routine instead of parsing the device tree directly. This is
in anticipation of introducing a new ibm,dynamic-memory-v2
property with a different format. This will allow the numa code
to use a single initialization routine per-LMB irregardless of
the device tree format.
Additionally, to support additional routines in numa.c that need
to look up LMB information, an late_init routine is added to drmem.c
to allocate the array of LMB information. This LMB array will provide
per-LMB information to separate the LMB data from the device tree
format.
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
We currently have code to parse the dynamic reconfiguration LMB
information from the ibm,dynamic-meory device tree property in
multiple locations; numa.c, prom.c, and pseries/hotplug-memory.c.
In anticipation of adding support for a version 2 of the
ibm,dynamic-memory property this patch aims to separate the device
tree information from the device tree format.
Doing this requires a two step process to avoid a possibly very large
bootmem allocation early in boot. During initial boot, new routines
are provided to walk the device tree property and make a call-back
for each LMB.
The second step (introduced in later patches) will allocate an
array of LMB information that can be used directly without needing
to know the DT format.
This approach provides the benefit of consolidating the device tree
property parsing to a single location and (eventually) providing
a common data structure for retrieving LMB information.
This patch introduces a routine to walk the ibm,dynamic-memory
property in the flattened device tree and updates the prom.c code
to use this to initialize memory.
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
