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    mm/mprotect: add a cond_resched() inside change_pmd_range() · 4991c09c
    Anshuman Khandual 提交于
    While testing on a large CPU system, detected the following RCU stall
    many times over the span of the workload.  This problem is solved by
    adding a cond_resched() in the change_pmd_range() function.
    
      INFO: rcu_sched detected stalls on CPUs/tasks:
       154-....: (670 ticks this GP) idle=022/140000000000000/0 softirq=2825/2825 fqs=612
       (detected by 955, t=6002 jiffies, g=4486, c=4485, q=90864)
      Sending NMI from CPU 955 to CPUs 154:
      NMI backtrace for cpu 154
      CPU: 154 PID: 147071 Comm: workload Not tainted 4.15.0-rc3+ #3
      NIP:  c0000000000b3f64 LR: c0000000000b33d4 CTR: 000000000000aa18
      REGS: 00000000a4b0fb44 TRAP: 0501   Not tainted  (4.15.0-rc3+)
      MSR:  8000000000009033 <SF,EE,ME,IR,DR,RI,LE>  CR: 22422082  XER: 00000000
      CFAR: 00000000006cf8f0 SOFTE: 1
      GPR00: 0010000000000000 c00003ef9b1cb8c0 c0000000010cc600 0000000000000000
      GPR04: 8e0000018c32b200 40017b3858fd6e00 8e0000018c32b208 40017b3858fd6e00
      GPR08: 8e0000018c32b210 40017b3858fd6e00 8e0000018c32b218 40017b3858fd6e00
      GPR12: ffffffffffffffff c00000000fb25100
      NIP [c0000000000b3f64] plpar_hcall9+0x44/0x7c
      LR [c0000000000b33d4] pSeries_lpar_flush_hash_range+0x384/0x420
      Call Trace:
        flush_hash_range+0x48/0x100
        __flush_tlb_pending+0x44/0xd0
        hpte_need_flush+0x408/0x470
        change_protection_range+0xaac/0xf10
        change_prot_numa+0x30/0xb0
        task_numa_work+0x2d0/0x3e0
        task_work_run+0x130/0x190
        do_notify_resume+0x118/0x120
        ret_from_except_lite+0x70/0x74
      Instruction dump:
      60000000 f8810028 7ca42b78 7cc53378 7ce63b78 7d074378 7d284b78 7d495378
      e9410060 e9610068 e9810070 44000022 <7d806378> e9810028 f88c0000 f8ac0008
    
    Link: http://lkml.kernel.org/r/20171214140551.5794-1-khandual@linux.vnet.ibm.comSigned-off-by: NAnshuman Khandual <khandual@linux.vnet.ibm.com>
    Suggested-by: NNicholas Piggin <npiggin@gmail.com>
    Acked-by: NMichal Hocko <mhocko@suse.com>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
    4991c09c
mprotect.c 13.9 KB