• Nathan Fontenot's avatar
    powerpc/pseries: Track LMB nid instead of using device tree · 7bd4b91a
    Nathan Fontenot authored
    [ Upstream commit b2d3b5ee ]
    
    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: default avatarNathan Fontenot <nfont@linux.vnet.ibm.com>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
    7bd4b91a
hotplug-memory.c 22.6 KB