* [PATCH 1/2] drivers/dax: Avoiding potential deadlock
@ 2017-04-11 5:26 Pushkar Jambhlekar
2017-04-11 5:26 ` [PATCH 2/2] drivers/dax: Changing RC value Pushkar Jambhlekar
2017-04-11 16:17 ` [PATCH 1/2] drivers/dax: Avoiding potential deadlock Dan Williams
0 siblings, 2 replies; 7+ messages in thread
From: Pushkar Jambhlekar @ 2017-04-11 5:26 UTC (permalink / raw)
To: Dan Williams, Dave Jiang, Andrew Morton, Johannes Thumshirn,
Ross Zwisler
Cc: linux-kernel, Pushkar Jambhlekar
dax_dev_huge_fault returning without releasing lock. Making code change to avoid this situation
Signed-off-by: Pushkar Jambhlekar <pushkar.iit@gmail.com>
---
drivers/dax/dax.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c
index 0d1ca24..fd9c4db 100644
--- a/drivers/dax/dax.c
+++ b/drivers/dax/dax.c
@@ -590,7 +590,7 @@ static int dax_dev_huge_fault(struct vm_fault *vmf,
rc = __dax_dev_pud_fault(dax_dev, vmf);
break;
default:
- return VM_FAULT_FALLBACK;
+ rc = VM_FAULT_FALLBACK;
}
rcu_read_unlock();
--
2.7.4
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH 2/2] drivers/dax: Changing RC value
2017-04-11 5:26 [PATCH 1/2] drivers/dax: Avoiding potential deadlock Pushkar Jambhlekar
@ 2017-04-11 5:26 ` Pushkar Jambhlekar
2017-04-11 20:58 ` Andrew Morton
2017-04-11 16:17 ` [PATCH 1/2] drivers/dax: Avoiding potential deadlock Dan Williams
1 sibling, 1 reply; 7+ messages in thread
From: Pushkar Jambhlekar @ 2017-04-11 5:26 UTC (permalink / raw)
To: Dan Williams, Dave Jiang, Andrew Morton, Johannes Thumshirn,
Ross Zwisler
Cc: linux-kernel, Pushkar Jambhlekar
Changing rc value from VM_FAULT_FALLBACK to VM_FAULT_SIGBUS for an unknown / unsupported fault size.
Signed-off-by: Pushkar Jambhlekar <pushkar.iit@gmail.com>
---
drivers/dax/dax.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c
index fd9c4db..6156fdc 100644
--- a/drivers/dax/dax.c
+++ b/drivers/dax/dax.c
@@ -590,7 +590,7 @@ static int dax_dev_huge_fault(struct vm_fault *vmf,
rc = __dax_dev_pud_fault(dax_dev, vmf);
break;
default:
- rc = VM_FAULT_FALLBACK;
+ rc = VM_FAULT_SIGBUS;
}
rcu_read_unlock();
--
2.7.4
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH 2/2] drivers/dax: Changing RC value
2017-04-11 5:26 ` [PATCH 2/2] drivers/dax: Changing RC value Pushkar Jambhlekar
@ 2017-04-11 20:58 ` Andrew Morton
2017-04-12 16:27 ` Dan Williams
0 siblings, 1 reply; 7+ messages in thread
From: Andrew Morton @ 2017-04-11 20:58 UTC (permalink / raw)
To: Pushkar Jambhlekar
Cc: Dan Williams, Dave Jiang, Johannes Thumshirn, Ross Zwisler,
linux-kernel
On Tue, 11 Apr 2017 10:56:45 +0530 Pushkar Jambhlekar <pushkar.iit@gmail.com> wrote:
> Changing rc value from VM_FAULT_FALLBACK to VM_FAULT_SIGBUS for an unknown / unsupported fault size.
>
> ...
>
> --- a/drivers/dax/dax.c
> +++ b/drivers/dax/dax.c
> @@ -590,7 +590,7 @@ static int dax_dev_huge_fault(struct vm_fault *vmf,
> rc = __dax_dev_pud_fault(dax_dev, vmf);
> break;
> default:
> - rc = VM_FAULT_FALLBACK;
> + rc = VM_FAULT_SIGBUS;
> }
> rcu_read_unlock();
The change seems to make sense but more info would be helpful. What
is wrong with the current code? ie, what goes wrong if we return
VM_FAULT_FALLBACK here?
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 2/2] drivers/dax: Changing RC value
2017-04-11 20:58 ` Andrew Morton
@ 2017-04-12 16:27 ` Dan Williams
0 siblings, 0 replies; 7+ messages in thread
From: Dan Williams @ 2017-04-12 16:27 UTC (permalink / raw)
To: Andrew Morton
Cc: Pushkar Jambhlekar, Dave Jiang, Johannes Thumshirn, Ross Zwisler,
linux-kernel@vger.kernel.org
On Tue, Apr 11, 2017 at 1:58 PM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Tue, 11 Apr 2017 10:56:45 +0530 Pushkar Jambhlekar <pushkar.iit@gmail.com> wrote:
>
>> Changing rc value from VM_FAULT_FALLBACK to VM_FAULT_SIGBUS for an unknown / unsupported fault size.
>>
>> ...
>>
>> --- a/drivers/dax/dax.c
>> +++ b/drivers/dax/dax.c
>> @@ -590,7 +590,7 @@ static int dax_dev_huge_fault(struct vm_fault *vmf,
>> rc = __dax_dev_pud_fault(dax_dev, vmf);
>> break;
>> default:
>> - rc = VM_FAULT_FALLBACK;
>> + rc = VM_FAULT_SIGBUS;
>> }
>> rcu_read_unlock();
>
> The change seems to make sense but more info would be helpful. What
> is wrong with the current code? ie, what goes wrong if we return
> VM_FAULT_FALLBACK here?
Hi Andrew, I took these two patches into my for-4.12/dax branch with
the following fixed up changelog:
commit 17756a4c681c320712798b783eb40006de9b4cc3
Author: Pushkar Jambhlekar <pushkar.iit@gmail.com>
Date: Tue Apr 11 09:12:25 2017 -0700
device-dax: fix dax_dev_huge_fault() unknown fault size handling
The default case for dax_dev_huge_fault() fault size handling mistakenly
returns when it should unlock. This is not a problem in practice since
the only three possible fault sizes are handled. Going forward, if the
core mm adds a new fault size beyond pte, pmd, or pud device-dax should
abort VM_FAULT_SIGBUS requests not VM_FAULT_FALLBACK since device-dax
guarantees a configured fault granularity for all faults.
Signed-off-by: Pushkar Jambhlekar <pushkar.iit@gmail.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c
index 19795eb35579..94036d92ed16 100644
--- a/drivers/dax/dax.c
+++ b/drivers/dax/dax.c
@@ -591,7 +591,7 @@ static int dax_dev_huge_fault(struct vm_fault *vmf,
rc = __dax_dev_pud_fault(dax_dev, vmf);
break;
default:
- return VM_FAULT_FALLBACK;
+ rc = VM_FAULT_SIGBUS;
}
srcu_read_unlock(&dax_srcu, id);
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH 1/2] drivers/dax: Avoiding potential deadlock
2017-04-11 5:26 [PATCH 1/2] drivers/dax: Avoiding potential deadlock Pushkar Jambhlekar
2017-04-11 5:26 ` [PATCH 2/2] drivers/dax: Changing RC value Pushkar Jambhlekar
@ 2017-04-11 16:17 ` Dan Williams
2017-04-12 4:19 ` Pushkar Jambhlekar
1 sibling, 1 reply; 7+ messages in thread
From: Dan Williams @ 2017-04-11 16:17 UTC (permalink / raw)
To: Pushkar Jambhlekar
Cc: Dave Jiang, Andrew Morton, Johannes Thumshirn, Ross Zwisler,
linux-kernel@vger.kernel.org
On Mon, Apr 10, 2017 at 10:26 PM, Pushkar Jambhlekar
<pushkar.iit@gmail.com> wrote:
> dax_dev_huge_fault returning without releasing lock. Making code change to avoid this situation
>
> Signed-off-by: Pushkar Jambhlekar <pushkar.iit@gmail.com>
> ---
> drivers/dax/dax.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c
> index 0d1ca24..fd9c4db 100644
> --- a/drivers/dax/dax.c
> +++ b/drivers/dax/dax.c
> @@ -590,7 +590,7 @@ static int dax_dev_huge_fault(struct vm_fault *vmf,
> rc = __dax_dev_pud_fault(dax_dev, vmf);
> break;
> default:
> - return VM_FAULT_FALLBACK;
> + rc = VM_FAULT_FALLBACK;
> }
> rcu_read_unlock();
Thanks Pushkar, I'll apply this and combine with patch 2 as well.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 1/2] drivers/dax: Avoiding potential deadlock
2017-04-11 16:17 ` [PATCH 1/2] drivers/dax: Avoiding potential deadlock Dan Williams
@ 2017-04-12 4:19 ` Pushkar Jambhlekar
0 siblings, 0 replies; 7+ messages in thread
From: Pushkar Jambhlekar @ 2017-04-12 4:19 UTC (permalink / raw)
To: Dan Williams
Cc: Dave Jiang, Andrew Morton, Johannes Thumshirn, Ross Zwisler,
linux-kernel@vger.kernel.org
Thanks Dan!
On Tue, Apr 11, 2017 at 9:47 PM, Dan Williams <dan.j.williams@intel.com> wrote:
> On Mon, Apr 10, 2017 at 10:26 PM, Pushkar Jambhlekar
> <pushkar.iit@gmail.com> wrote:
>> dax_dev_huge_fault returning without releasing lock. Making code change to avoid this situation
>>
>> Signed-off-by: Pushkar Jambhlekar <pushkar.iit@gmail.com>
>> ---
>> drivers/dax/dax.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c
>> index 0d1ca24..fd9c4db 100644
>> --- a/drivers/dax/dax.c
>> +++ b/drivers/dax/dax.c
>> @@ -590,7 +590,7 @@ static int dax_dev_huge_fault(struct vm_fault *vmf,
>> rc = __dax_dev_pud_fault(dax_dev, vmf);
>> break;
>> default:
>> - return VM_FAULT_FALLBACK;
>> + rc = VM_FAULT_FALLBACK;
>> }
>> rcu_read_unlock();
>
> Thanks Pushkar, I'll apply this and combine with patch 2 as well.
--
Jambhlekar Pushkar Arun
^ permalink raw reply [flat|nested] 7+ messages in thread
[parent not found: <Dave Jiang <dave.jiang@intel.com>]
* [PATCH 1/2] drivers/dax: Avoiding potential deadlock
[not found] <Dave Jiang <dave.jiang@intel.com>
@ 2017-04-11 5:26 ` Pushkar Jambhlekar
2017-04-11 5:26 ` [PATCH 2/2] drivers/dax: Changing RC value Pushkar Jambhlekar
0 siblings, 1 reply; 7+ messages in thread
From: Pushkar Jambhlekar @ 2017-04-11 5:26 UTC (permalink / raw)
To: Dan Williams; +Cc: linux-kernel, Pushkar Jambhlekar
dax_dev_huge_fault returning without releasing lock. Making code change to avoid this situation
Signed-off-by: Pushkar Jambhlekar <pushkar.iit@gmail.com>
---
drivers/dax/dax.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c
index 0d1ca24..fd9c4db 100644
--- a/drivers/dax/dax.c
+++ b/drivers/dax/dax.c
@@ -590,7 +590,7 @@ static int dax_dev_huge_fault(struct vm_fault *vmf,
rc = __dax_dev_pud_fault(dax_dev, vmf);
break;
default:
- return VM_FAULT_FALLBACK;
+ rc = VM_FAULT_FALLBACK;
}
rcu_read_unlock();
--
2.7.4
^ permalink raw reply related [flat|nested] 7+ messages in thread* [PATCH 2/2] drivers/dax: Changing RC value
2017-04-11 5:26 ` Pushkar Jambhlekar
@ 2017-04-11 5:26 ` Pushkar Jambhlekar
0 siblings, 0 replies; 7+ messages in thread
From: Pushkar Jambhlekar @ 2017-04-11 5:26 UTC (permalink / raw)
To: Dan Williams; +Cc: linux-kernel, Pushkar Jambhlekar
Changing rc value from VM_FAULT_FALLBACK to VM_FAULT_SIGBUS for an unknown / unsupported fault size.
Signed-off-by: Pushkar Jambhlekar <pushkar.iit@gmail.com>
---
drivers/dax/dax.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c
index fd9c4db..6156fdc 100644
--- a/drivers/dax/dax.c
+++ b/drivers/dax/dax.c
@@ -590,7 +590,7 @@ static int dax_dev_huge_fault(struct vm_fault *vmf,
rc = __dax_dev_pud_fault(dax_dev, vmf);
break;
default:
- rc = VM_FAULT_FALLBACK;
+ rc = VM_FAULT_SIGBUS;
}
rcu_read_unlock();
--
2.7.4
^ permalink raw reply related [flat|nested] 7+ messages in thread
end of thread, other threads:[~2017-04-12 16:27 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
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2017-04-11 5:26 [PATCH 1/2] drivers/dax: Avoiding potential deadlock Pushkar Jambhlekar
2017-04-11 5:26 ` [PATCH 2/2] drivers/dax: Changing RC value Pushkar Jambhlekar
2017-04-11 20:58 ` Andrew Morton
2017-04-12 16:27 ` Dan Williams
2017-04-11 16:17 ` [PATCH 1/2] drivers/dax: Avoiding potential deadlock Dan Williams
2017-04-12 4:19 ` Pushkar Jambhlekar
[not found] <Dave Jiang <dave.jiang@intel.com>
2017-04-11 5:26 ` Pushkar Jambhlekar
2017-04-11 5:26 ` [PATCH 2/2] drivers/dax: Changing RC value Pushkar Jambhlekar
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