linux.git/arch/powerpc/platforms/pseries/hotplug-cpu.c, branch v5.4.301

powerpc/pseries: Stop calling printk in rtas_stop_self()

2021-05-19T08:08:23+00:00

[ Upstream commit ed8029d7b472369a010a1901358567ca3b6dbb0d ]

RCU complains about us calling printk() from an offline CPU:

  =============================
  WARNING: suspicious RCU usage
  5.12.0-rc7-02874-g7cf90e481cb8 #1 Not tainted
  -----------------------------
  kernel/locking/lockdep.c:3568 RCU-list traversed in non-reader section!!

  other info that might help us debug this:

  RCU used illegally from offline CPU!
  rcu_scheduler_active = 2, debug_locks = 1
  no locks held by swapper/0/0.

  stack backtrace:
  CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.12.0-rc7-02874-g7cf90e481cb8 #1
  Call Trace:
    dump_stack+0xec/0x144 (unreliable)
    lockdep_rcu_suspicious+0x124/0x144
    __lock_acquire+0x1098/0x28b0
    lock_acquire+0x128/0x600
    _raw_spin_lock_irqsave+0x6c/0xc0
    down_trylock+0x2c/0x70
    __down_trylock_console_sem+0x60/0x140
    vprintk_emit+0x1a8/0x4b0
    vprintk_func+0xcc/0x200
    printk+0x40/0x54
    pseries_cpu_offline_self+0xc0/0x120
    arch_cpu_idle_dead+0x54/0x70
    do_idle+0x174/0x4a0
    cpu_startup_entry+0x38/0x40
    rest_init+0x268/0x388
    start_kernel+0x748/0x790
    start_here_common+0x1c/0x614

Which happens because by the time we get to rtas_stop_self() we are
already offline. In addition the message can be spammy, and is not that
helpful for users, so remove it.

Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20210418135413.1204031-1-mpe@ellerman.id.au
Signed-off-by: Sasha Levin

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

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 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman

powerpc/pseries: Perform full re-add of CPU for topology update post-migration

2019-01-30T12:28:56+00:00

On pseries systems, performing a partition migration can result in
altering the nodes a CPU is assigned to on the destination system. For
exampl, pre-migration on the source system CPUs are in node 1 and 3,
post-migration on the destination system CPUs are in nodes 2 and 3.

Handling the node change for a CPU can cause corruption in the slab
cache if we hit a timing where a CPUs node is changed while cache_reap()
is invoked. The corruption occurs because the slab cache code appears
to rely on the CPU and slab cache pages being on the same node.

The current dynamic updating of a CPUs node done in arch/powerpc/mm/numa.c
does not prevent us from hitting this scenario.

Changing the device tree property update notification handler that
recognizes an affinity change for a CPU to do a full DLPAR remove and
add of the CPU instead of dynamically changing its node resolves this
issue.

Signed-off-by: Nathan Fontenot 
Signed-off-by: Michael W. Bringmann 
Tested-by: Michael W. Bringmann 
Signed-off-by: Michael Ellerman

powerpc: Convert to using %pOFn instead of device_node.name

2018-10-03T05:40:01+00:00

In preparation to remove the node name pointer from struct device_node,
convert printf users to use the %pOFn format specifier.

Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Michael Ellerman 
Cc: Arnd Bergmann 
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Rob Herring 
Signed-off-by: Michael Ellerman

Merge branch 'topic/paca' into next

2018-03-30T22:09:36+00:00

Bring in yet another series that touches KVM code, and might need to
be merged into the kvm-ppc branch to resolve conflicts.

This required some changes in pnv_power9_force_smt4_catch/release()
due to the paca array becomming an array of pointers.

powerpc/64: Use array of paca pointers and allocate pacas individually

2018-03-30T12:34:23+00:00

Change the paca array into an array of pointers to pacas. Allocate
pacas individually.

This allows flexibility in where the PACAs are allocated. Future work
will allocate them node-local. Platforms that don't have address limits
on PACAs would be able to defer PACA allocations until later in boot
rather than allocate all possible ones up-front then freeing unused.

This is slightly more overhead (one additional indirection) for cross
CPU paca references, but those aren't too common.

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman

powerpc/pseries: Fix build break for SPLPAR=n and CPU hotplug

2018-02-13T11:38:39+00:00

Commit e67e02a544e9 ("powerpc/pseries: Fix cpu hotplug crash with
memoryless nodes") adds an unconditional call to
find_and_online_cpu_nid(), which is only declared if CONFIG_PPC_SPLPAR
is enabled. This results in the following build error if this is not
the case.

  arch/powerpc/platforms/pseries/hotplug-cpu.o: In function `dlpar_online_cpu':
  arch/powerpc/platforms/pseries/hotplug-cpu.c:369:
  			undefined reference to `.find_and_online_cpu_nid'

Follow the guideline provided by similar functions and provide a dummy
function if CONFIG_PPC_SPLPAR is not enabled. This also moves the
external function declaration into an include file where it should be.

Fixes: e67e02a544e9 ("powerpc/pseries: Fix cpu hotplug crash with memoryless nodes")
Signed-off-by: Guenter Roeck 
[mpe: Change subject to emphasise the build fix]
Signed-off-by: Michael Ellerman

powerpc/numa: Invalidate numa_cpu_lookup_table on cpu remove

2018-02-08T12:56:10+00:00

When DLPAR removing a CPU, the unmapping of the cpu from a node in
unmap_cpu_from_node() should also invalidate the CPUs entry in the
numa_cpu_lookup_table. There is not a guarantee that on a subsequent
DLPAR add of the CPU the associativity will be the same and thus
could be in a different node. Invalidating the entry in the
numa_cpu_lookup_table causes the associativity to be read from the
device tree at the time of the add.

The current behavior of not invalidating the CPUs entry in the
numa_cpu_lookup_table can result in scenarios where the the topology
layout of CPUs in the partition does not match the device tree
or the topology reported by the HMC.

This bug looks like it was introduced in 2004 in the commit titled
"ppc64: cpu hotplug notifier for numa", which is 6b15e4e87e32 in the
linux-fullhist tree. Hence tag it for all stable releases.

Cc: stable@vger.kernel.org
Signed-off-by: Nathan Fontenot 
Reviewed-by: Tyrel Datwyler 
Signed-off-by: Michael Ellerman

powerpc/pseries: Fix cpu hotplug crash with memoryless nodes

2018-01-27T09:59:45+00:00

On powerpc systems with shared configurations of CPUs and memory and
memoryless nodes at boot, an event ordering problem was observed on a
SLES12 build platforms with the hot-add of CPUs to the memoryless
nodes.

* The most common error occurred when the memory SLAB driver attempted
  to reference the memoryless node to which a CPU was being added
  before the kernel had finished initializing all of the data
  structures for the CPU and exited 'device_online' under
  DLPAR/hot-add.

  Normally the memoryless node would be initialized through the call
  path device_online ... arch_update_cpu_topology ... find_cpu_nid ...
  try_online_node. This patch ensures that the powerpc node will be
  initialized as early as possible, even if it was memoryless and
  CPU-less at the point when we are trying to hot-add a new CPU to it.

Signed-off-by: Michael Bringmann 
Reviewed-by: Nathan Fontenot 
Signed-off-by: Michael Ellerman

powerpc/hotplug: Improve responsiveness of hotplug change

2017-10-16T12:12:04+00:00

powerpc/hotplug: On Power systems with shared configurations of CPUs
and memory, there are some issues with the association of additional
CPUs and memory to nodes when hot-adding resources.  During hotplug
CPU operations, this patch resets the timer on topology update work
function to a small value to better ensure that the CPU topology is
detected and configured sooner.

Signed-off-by: Michael Bringmann 
Signed-off-by: Michael Ellerman