To backport the patc
commit 8604895a34d92f5e186ceb931b0d1b384030ea3d
to the 4.4-stable tree, please try the following backport:
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
--- a/arch/powerpc/mm/numa.c 2018-10-02 09:03:06.232491410 -0500
+++ b/arch/powerpc/mm/numa.c 2018-10-02 09:04:17.152494472 -0500
@@ -1606,7 +1606,8 @@
{
topology_timer.data = 0;
topology_timer.expires = jiffies + topology_timer_secs * HZ;
- mod_timer(&topology_timer, topology_timer.expires);
+ if (vphn_enabled)
+ mod_timer(&topology_timer, topology_timer.expires);
}
#ifdef CONFIG_SMP
On 10/02/2018 07:18 AM, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
>
> The patch below does not apply to the 4.4-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
>
> thanks,
>
> greg k-h
>
> ------------------ original commit in Linus's tree ------------------
>
>>From 8604895a34d92f5e186ceb931b0d1b384030ea3d Mon Sep 17 00:00:00 2001
> From: Michael Bringmann <mwb@xxxxxxxxxxxxxxxxxx>
> Date: Thu, 20 Sep 2018 11:45:13 -0500
> Subject: [PATCH] powerpc/pseries: Fix unitialized timer reset on migration
>
> After migration of a powerpc LPAR, the kernel executes code to
> update the system state to reflect new platform characteristics.
>
> Such changes include modifications to device tree properties provided
> to the system by PHYP. Property notifications received by the
> post_mobility_fixup() code are passed along to the kernel in general
> through a call to of_update_property() which in turn passes such
> events back to all modules through entries like the '.notifier_call'
> function within the NUMA module.
>
> When the NUMA module updates its state, it resets its event timer. If
> this occurs after a previous call to stop_topology_update() or on a
> system without VPHN enabled, the code runs into an unitialized timer
> structure and crashes. This patch adds a safety check along this path
> toward the problem code.
>
> An example crash log is as follows.
>
> ibmvscsi 30000081: Re-enabling adapter!
> ------------[ cut here ]------------
> kernel BUG at kernel/time/timer.c:958!
> Oops: Exception in kernel mode, sig: 5 [#1]
> LE SMP NR_CPUS=2048 NUMA pSeries
> Modules linked in: nfsv3 nfs_acl nfs tcp_diag udp_diag inet_diag lockd unix_diag af_packet_diag netlink_diag grace fscache sunrpc xts vmx_crypto pseries_rng sg binfmt_misc ip_tables xfs libcrc32c sd_mod ibmvscsi ibmveth scsi_transport_srp dm_mirror dm_region_hash dm_log dm_mod
> CPU: 11 PID: 3067 Comm: drmgr Not tainted 4.17.0+ #179
> ...
> NIP mod_timer+0x4c/0x400
> LR reset_topology_timer+0x40/0x60
> Call Trace:
> 0xc0000003f9407830 (unreliable)
> reset_topology_timer+0x40/0x60
> dt_update_callback+0x100/0x120
> notifier_call_chain+0x90/0x100
> __blocking_notifier_call_chain+0x60/0x90
> of_property_notify+0x90/0xd0
> of_update_property+0x104/0x150
> update_dt_property+0xdc/0x1f0
> pseries_devicetree_update+0x2d0/0x510
> post_mobility_fixup+0x7c/0xf0
> migration_store+0xa4/0xc0
> kobj_attr_store+0x30/0x60
> sysfs_kf_write+0x64/0xa0
> kernfs_fop_write+0x16c/0x240
> __vfs_write+0x40/0x200
> vfs_write+0xc8/0x240
> ksys_write+0x5c/0x100
> system_call+0x58/0x6c
>
> Fixes: 5d88aa85c00b ("powerpc/pseries: Update CPU maps when device tree is updated")
> Cc: stable@xxxxxxxxxxxxxxx # v3.10+
> Signed-off-by: Michael Bringmann <mwb@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
>
> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index 35ac5422903a..b5a71baedbc2 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -1452,7 +1452,8 @@ static struct timer_list topology_timer;
>
> static void reset_topology_timer(void)
> {
> - mod_timer(&topology_timer, jiffies + topology_timer_secs * HZ);
> + if (vphn_enabled)
> + mod_timer(&topology_timer, jiffies + topology_timer_secs * HZ);
> }
>
> #ifdef CONFIG_SMP
>
>
--
Michael W. Bringmann
Linux Technology Center
IBM Corporation
Tie-Line 363-5196
External: (512) 286-5196
Cell: (512) 466-0650
mwb@xxxxxxxxxxxxxxxxxx
