releases/4.14.13/mm-mprotect-add-a-cond_resched-inside-change_pmd_range.patch

   1 From 4991c09c7c812dba13ea9be79a68b4565bb1fa4e Mon Sep 17 00:00:00 2001
   2 From: Anshuman Khandual <khandual@linux.vnet.ibm.com>
   3 Date: Thu, 4 Jan 2018 16:17:52 -0800
   4 Subject: mm/mprotect: add a cond_resched() inside change_pmd_range()
   5
   6 From: Anshuman Khandual <khandual@linux.vnet.ibm.com>
   7
   8 commit 4991c09c7c812dba13ea9be79a68b4565bb1fa4e upstream.
   9
  10 While testing on a large CPU system, detected the following RCU stall
  11 many times over the span of the workload.  This problem is solved by
  12 adding a cond_resched() in the change_pmd_range() function.
  13
  14   INFO: rcu_sched detected stalls on CPUs/tasks:
  15    154-....: (670 ticks this GP) idle=022/140000000000000/0 softirq=2825/2825 fqs=612
  16    (detected by 955, t=6002 jiffies, g=4486, c=4485, q=90864)
  17   Sending NMI from CPU 955 to CPUs 154:
  18   NMI backtrace for cpu 154
  19   CPU: 154 PID: 147071 Comm: workload Not tainted 4.15.0-rc3+ #3
  20   NIP:  c0000000000b3f64 LR: c0000000000b33d4 CTR: 000000000000aa18
  21   REGS: 00000000a4b0fb44 TRAP: 0501   Not tainted  (4.15.0-rc3+)
  22   MSR:  8000000000009033 <SF,EE,ME,IR,DR,RI,LE>  CR: 22422082  XER: 00000000
  23   CFAR: 00000000006cf8f0 SOFTE: 1
  24   GPR00: 0010000000000000 c00003ef9b1cb8c0 c0000000010cc600 0000000000000000
  25   GPR04: 8e0000018c32b200 40017b3858fd6e00 8e0000018c32b208 40017b3858fd6e00
  26   GPR08: 8e0000018c32b210 40017b3858fd6e00 8e0000018c32b218 40017b3858fd6e00
  27   GPR12: ffffffffffffffff c00000000fb25100
  28   NIP [c0000000000b3f64] plpar_hcall9+0x44/0x7c
  29   LR [c0000000000b33d4] pSeries_lpar_flush_hash_range+0x384/0x420
  30   Call Trace:
  31     flush_hash_range+0x48/0x100
  32     __flush_tlb_pending+0x44/0xd0
  33     hpte_need_flush+0x408/0x470
  34     change_protection_range+0xaac/0xf10
  35     change_prot_numa+0x30/0xb0
  36     task_numa_work+0x2d0/0x3e0
  37     task_work_run+0x130/0x190
  38     do_notify_resume+0x118/0x120
  39     ret_from_except_lite+0x70/0x74
  40   Instruction dump:
  41   60000000 f8810028 7ca42b78 7cc53378 7ce63b78 7d074378 7d284b78 7d495378
  42   e9410060 e9610068 e9810070 44000022 <7d806378> e9810028 f88c0000 f8ac0008
  43
  44 Link: http://lkml.kernel.org/r/20171214140551.5794-1-khandual@linux.vnet.ibm.com
  45 Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
  46 Suggested-by: Nicholas Piggin <npiggin@gmail.com>
  47 Acked-by: Michal Hocko <mhocko@suse.com>
  48 Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
  49 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
  50 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  51
  52 ---
  53  mm/mprotect.c |    6 ++++--
  54  1 file changed, 4 insertions(+), 2 deletions(-)
  55
  56 --- a/mm/mprotect.c
  57 +++ b/mm/mprotect.c
  58 @@ -166,7 +166,7 @@ static inline unsigned long change_pmd_r
  59                 next = pmd_addr_end(addr, end);
  60                 if (!is_swap_pmd(*pmd) && !pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)
  61                                 && pmd_none_or_clear_bad(pmd))
  62 -                       continue;
  63 +                       goto next;
  64
  65                 /* invoke the mmu notifier if the pmd is populated */
  66                 if (!mni_start) {
  67 @@ -188,7 +188,7 @@ static inline unsigned long change_pmd_r
  68                                         }
  69
  70                                         /* huge pmd was handled */
  71 -                                       continue;
  72 +                                       goto next;
  73                                 }
  74                         }
  75                         /* fall through, the trans huge pmd just split */
  76 @@ -196,6 +196,8 @@ static inline unsigned long change_pmd_r
  77                 this_pages = change_pte_range(vma, pmd, addr, next, newprot,
  78                                  dirty_accountable, prot_numa);
  79                 pages += this_pages;
  80 +next:
  81 +               cond_resched();
  82         } while (pmd++, addr = next, addr != end);
  83
  84         if (mni_start)