* [PATCH] mm/mprotect: Add a cond_resched() inside change_pte_range()
@ 2017-12-14 5:10 ` Anshuman Khandual
0 siblings, 0 replies; 4+ messages in thread
From: Anshuman Khandual @ 2017-12-14 5:10 UTC (permalink / raw)
To: linux-mm, linux-kernel; +Cc: akpm, mhocko
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_pte_range()
function.
[ 850.962530] INFO: rcu_sched detected stalls on CPUs/tasks:
[ 850.962584] 154-....: (670 ticks this GP) idle=022/140000000000000/0 softirq=2825/2825 fqs=612
[ 850.962605] (detected by 955, t=6002 jiffies, g=4486, c=4485, q=90864)
[ 850.962895] Sending NMI from CPU 955 to CPUs 154:
[ 850.992667] NMI backtrace for cpu 154
[ 850.993069] CPU: 154 PID: 147071 Comm: workload Not tainted 4.15.0-rc3+ #3
[ 850.993258] NIP: c0000000000b3f64 LR: c0000000000b33d4 CTR: 000000000000aa18
[ 850.993503] REGS: 00000000a4b0fb44 TRAP: 0501 Not tainted (4.15.0-rc3+)
[ 850.993707] MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE> CR: 22422082 XER: 00000000
[ 850.994386] CFAR: 00000000006cf8f0 SOFTE: 1
GPR00: 0010000000000000 c00003ef9b1cb8c0 c0000000010cc600 0000000000000000
GPR04: 8e0000018c32b200 40017b3858fd6e00 8e0000018c32b208 40017b3858fd6e00
GPR08: 8e0000018c32b210 40017b3858fd6e00 8e0000018c32b218 40017b3858fd6e00
GPR12: ffffffffffffffff c00000000fb25100
[ 850.995976] NIP [c0000000000b3f64] plpar_hcall9+0x44/0x7c
[ 850.996174] LR [c0000000000b33d4] pSeries_lpar_flush_hash_range+0x384/0x420
[ 850.996401] Call Trace:
[ 850.996600] [c00003ef9b1cb8c0] [c00003fa8fff7d40] 0xc00003fa8fff7d40 (unreliable)
[ 850.996959] [c00003ef9b1cba40] [c0000000000688a8] flush_hash_range+0x48/0x100
[ 850.997261] [c00003ef9b1cba90] [c000000000071b14] __flush_tlb_pending+0x44/0xd0
[ 850.997600] [c00003ef9b1cbac0] [c000000000071fa8] hpte_need_flush+0x408/0x470
[ 850.997958] [c00003ef9b1cbb30] [c0000000002c646c] change_protection_range+0xaac/0xf10
[ 850.998180] [c00003ef9b1cbcb0] [c0000000002f2510] change_prot_numa+0x30/0xb0
[ 850.998502] [c00003ef9b1cbce0] [c00000000013a950] task_numa_work+0x2d0/0x3e0
[ 850.998816] [c00003ef9b1cbda0] [c00000000011ea30] task_work_run+0x130/0x190
[ 850.999121] [c00003ef9b1cbe00] [c00000000001bcd8] do_notify_resume+0x118/0x120
[ 850.999421] [c00003ef9b1cbe30] [c00000000000b744] ret_from_except_lite+0x70/0x74
[ 850.999716] Instruction dump:
[ 850.999959] 60000000 f8810028 7ca42b78 7cc53378 7ce63b78 7d074378 7d284b78 7d495378
[ 851.000575] e9410060 e9610068 e9810070 44000022 <7d806378> e9810028 f88c0000 f8ac0008
Suggested-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
---
mm/mprotect.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/mm/mprotect.c b/mm/mprotect.c
index ec39f73..4fce0f5 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -144,6 +144,7 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
} while (pte++, addr += PAGE_SIZE, addr != end);
arch_leave_lazy_mmu_mode();
pte_unmap_unlock(pte - 1, ptl);
+ cond_resched();
return pages;
}
--
2.9.3
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH] mm/mprotect: Add a cond_resched() inside change_pte_range()
@ 2017-12-14 5:10 ` Anshuman Khandual
0 siblings, 0 replies; 4+ messages in thread
From: Anshuman Khandual @ 2017-12-14 5:10 UTC (permalink / raw)
To: linux-mm, linux-kernel; +Cc: akpm, mhocko
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_pte_range()
function.
[ 850.962530] INFO: rcu_sched detected stalls on CPUs/tasks:
[ 850.962584] 154-....: (670 ticks this GP) idle=022/140000000000000/0 softirq=2825/2825 fqs=612
[ 850.962605] (detected by 955, t=6002 jiffies, g=4486, c=4485, q=90864)
[ 850.962895] Sending NMI from CPU 955 to CPUs 154:
[ 850.992667] NMI backtrace for cpu 154
[ 850.993069] CPU: 154 PID: 147071 Comm: workload Not tainted 4.15.0-rc3+ #3
[ 850.993258] NIP: c0000000000b3f64 LR: c0000000000b33d4 CTR: 000000000000aa18
[ 850.993503] REGS: 00000000a4b0fb44 TRAP: 0501 Not tainted (4.15.0-rc3+)
[ 850.993707] MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE> CR: 22422082 XER: 00000000
[ 850.994386] CFAR: 00000000006cf8f0 SOFTE: 1
GPR00: 0010000000000000 c00003ef9b1cb8c0 c0000000010cc600 0000000000000000
GPR04: 8e0000018c32b200 40017b3858fd6e00 8e0000018c32b208 40017b3858fd6e00
GPR08: 8e0000018c32b210 40017b3858fd6e00 8e0000018c32b218 40017b3858fd6e00
GPR12: ffffffffffffffff c00000000fb25100
[ 850.995976] NIP [c0000000000b3f64] plpar_hcall9+0x44/0x7c
[ 850.996174] LR [c0000000000b33d4] pSeries_lpar_flush_hash_range+0x384/0x420
[ 850.996401] Call Trace:
[ 850.996600] [c00003ef9b1cb8c0] [c00003fa8fff7d40] 0xc00003fa8fff7d40 (unreliable)
[ 850.996959] [c00003ef9b1cba40] [c0000000000688a8] flush_hash_range+0x48/0x100
[ 850.997261] [c00003ef9b1cba90] [c000000000071b14] __flush_tlb_pending+0x44/0xd0
[ 850.997600] [c00003ef9b1cbac0] [c000000000071fa8] hpte_need_flush+0x408/0x470
[ 850.997958] [c00003ef9b1cbb30] [c0000000002c646c] change_protection_range+0xaac/0xf10
[ 850.998180] [c00003ef9b1cbcb0] [c0000000002f2510] change_prot_numa+0x30/0xb0
[ 850.998502] [c00003ef9b1cbce0] [c00000000013a950] task_numa_work+0x2d0/0x3e0
[ 850.998816] [c00003ef9b1cbda0] [c00000000011ea30] task_work_run+0x130/0x190
[ 850.999121] [c00003ef9b1cbe00] [c00000000001bcd8] do_notify_resume+0x118/0x120
[ 850.999421] [c00003ef9b1cbe30] [c00000000000b744] ret_from_except_lite+0x70/0x74
[ 850.999716] Instruction dump:
[ 850.999959] 60000000 f8810028 7ca42b78 7cc53378 7ce63b78 7d074378 7d284b78 7d495378
[ 851.000575] e9410060 e9610068 e9810070 44000022 <7d806378> e9810028 f88c0000 f8ac0008
Suggested-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
---
mm/mprotect.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/mm/mprotect.c b/mm/mprotect.c
index ec39f73..4fce0f5 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -144,6 +144,7 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
} while (pte++, addr += PAGE_SIZE, addr != end);
arch_leave_lazy_mmu_mode();
pte_unmap_unlock(pte - 1, ptl);
+ cond_resched();
return pages;
}
--
2.9.3
--
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^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] mm/mprotect: Add a cond_resched() inside change_pte_range()
2017-12-14 5:10 ` Anshuman Khandual
@ 2017-12-14 9:33 ` Michal Hocko
-1 siblings, 0 replies; 4+ messages in thread
From: Michal Hocko @ 2017-12-14 9:33 UTC (permalink / raw)
To: Anshuman Khandual; +Cc: linux-mm, linux-kernel, akpm
On Thu 14-12-17 10:40:21, Anshuman Khandual wrote:
[...]
> diff --git a/mm/mprotect.c b/mm/mprotect.c
> index ec39f73..4fce0f5 100644
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -144,6 +144,7 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
> } while (pte++, addr += PAGE_SIZE, addr != end);
> arch_leave_lazy_mmu_mode();
> pte_unmap_unlock(pte - 1, ptl);
> + cond_resched();
>
> return pages;
> }
I would put this one level up to change_pmd_range to catch large THP
backed regions. Something we do in zap_pmd_range. Other than that the
patch makes sense to me.
--
Michal Hocko
SUSE Labs
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] mm/mprotect: Add a cond_resched() inside change_pte_range()
@ 2017-12-14 9:33 ` Michal Hocko
0 siblings, 0 replies; 4+ messages in thread
From: Michal Hocko @ 2017-12-14 9:33 UTC (permalink / raw)
To: Anshuman Khandual; +Cc: linux-mm, linux-kernel, akpm
On Thu 14-12-17 10:40:21, Anshuman Khandual wrote:
[...]
> diff --git a/mm/mprotect.c b/mm/mprotect.c
> index ec39f73..4fce0f5 100644
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -144,6 +144,7 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
> } while (pte++, addr += PAGE_SIZE, addr != end);
> arch_leave_lazy_mmu_mode();
> pte_unmap_unlock(pte - 1, ptl);
> + cond_resched();
>
> return pages;
> }
I would put this one level up to change_pmd_range to catch large THP
backed regions. Something we do in zap_pmd_range. Other than that the
patch makes sense to me.
--
Michal Hocko
SUSE Labs
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2017-12-14 9:33 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2017-12-14 5:10 [PATCH] mm/mprotect: Add a cond_resched() inside change_pte_range() Anshuman Khandual
2017-12-14 5:10 ` Anshuman Khandual
2017-12-14 9:33 ` Michal Hocko
2017-12-14 9:33 ` Michal Hocko
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