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* [PATCH] mm, memory-failure: clarify error message
@ 2019-05-17  4:08 Jane Chu
  2019-05-17  4:48 ` Anshuman Khandual
  2019-05-17 18:20 ` Verma, Vishal L
  0 siblings, 2 replies; 6+ messages in thread
From: Jane Chu @ 2019-05-17  4:08 UTC (permalink / raw)
  To: n-horiguchi, linux-mm, linux-kernel; +Cc: linux-nvdimm

Some user who install SIGBUS handler that does longjmp out
therefore keeping the process alive is confused by the error
message
  "[188988.765862] Memory failure: 0x1840200: Killing
   cellsrv:33395 due to hardware memory corruption"
Slightly modify the error message to improve clarity.

Signed-off-by: Jane Chu <jane.chu@oracle.com>
---
 mm/memory-failure.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index fc8b517..14de5e2 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -216,10 +216,9 @@ static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
 	short addr_lsb = tk->size_shift;
 	int ret;
 
-	pr_err("Memory failure: %#lx: Killing %s:%d due to hardware memory corruption\n",
-		pfn, t->comm, t->pid);
-
 	if ((flags & MF_ACTION_REQUIRED) && t->mm == current->mm) {
+		pr_err("Memory failure: %#lx: Killing %s:%d due to hardware memory "
+			"corruption\n", pfn, t->comm, t->pid);
 		ret = force_sig_mceerr(BUS_MCEERR_AR, (void __user *)tk->addr,
 				       addr_lsb, current);
 	} else {
@@ -229,6 +228,8 @@ static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
 		 * This could cause a loop when the user sets SIGBUS
 		 * to SIG_IGN, but hopefully no one will do that?
 		 */
+		pr_err("Memory failure: %#lx: Sending SIGBUS to %s:%d due to hardware "
+			"memory corruption\n", pfn, t->comm, t->pid);
 		ret = send_sig_mceerr(BUS_MCEERR_AO, (void __user *)tk->addr,
 				      addr_lsb, t);  /* synchronous? */
 	}
-- 
1.8.3.1


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: [PATCH] mm, memory-failure: clarify error message
  2019-05-17  4:08 [PATCH] mm, memory-failure: clarify error message Jane Chu
@ 2019-05-17  4:48 ` Anshuman Khandual
  2019-05-20 10:21   ` Naoya Horiguchi
  2019-05-21  1:53   ` Jane Chu
  2019-05-17 18:20 ` Verma, Vishal L
  1 sibling, 2 replies; 6+ messages in thread
From: Anshuman Khandual @ 2019-05-17  4:48 UTC (permalink / raw)
  To: Jane Chu, n-horiguchi, linux-mm, linux-kernel; +Cc: linux-nvdimm



On 05/17/2019 09:38 AM, Jane Chu wrote:
> Some user who install SIGBUS handler that does longjmp out

What the longjmp about ? Are you referring to the mechanism of catching the
signal which was registered ?

> therefore keeping the process alive is confused by the error
> message
>   "[188988.765862] Memory failure: 0x1840200: Killing
>    cellsrv:33395 due to hardware memory corruption"

Its a valid point because those are two distinct actions.

> Slightly modify the error message to improve clarity.
> 
> Signed-off-by: Jane Chu <jane.chu@oracle.com>
> ---
>  mm/memory-failure.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index fc8b517..14de5e2 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -216,10 +216,9 @@ static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
>  	short addr_lsb = tk->size_shift;
>  	int ret;
>  
> -	pr_err("Memory failure: %#lx: Killing %s:%d due to hardware memory corruption\n",
> -		pfn, t->comm, t->pid);
> -
>  	if ((flags & MF_ACTION_REQUIRED) && t->mm == current->mm) {
> +		pr_err("Memory failure: %#lx: Killing %s:%d due to hardware memory "
> +			"corruption\n", pfn, t->comm, t->pid);
>  		ret = force_sig_mceerr(BUS_MCEERR_AR, (void __user *)tk->addr,
>  				       addr_lsb, current);
>  	} else {
> @@ -229,6 +228,8 @@ static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
>  		 * This could cause a loop when the user sets SIGBUS
>  		 * to SIG_IGN, but hopefully no one will do that?
>  		 */
> +		pr_err("Memory failure: %#lx: Sending SIGBUS to %s:%d due to hardware "
> +			"memory corruption\n", pfn, t->comm, t->pid);
>  		ret = send_sig_mceerr(BUS_MCEERR_AO, (void __user *)tk->addr,
>  				      addr_lsb, t);  /* synchronous? */

As both the pr_err() messages are very similar, could not we just switch between "Killing"
and "Sending SIGBUS to" based on a variable e.g action_[kill|sigbus] evaluated previously
with ((flags & MF_ACTION_REQUIRED) && t->mm == current->mm).


^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] mm, memory-failure: clarify error message
  2019-05-17  4:08 [PATCH] mm, memory-failure: clarify error message Jane Chu
  2019-05-17  4:48 ` Anshuman Khandual
@ 2019-05-17 18:20 ` Verma, Vishal L
  1 sibling, 0 replies; 6+ messages in thread
From: Verma, Vishal L @ 2019-05-17 18:20 UTC (permalink / raw)
  To: jane.chu, n-horiguchi, linux-mm, linux-kernel; +Cc: linux-nvdimm

On Thu, 2019-05-16 at 22:08 -0600, Jane Chu wrote:
> Some user who install SIGBUS handler that does longjmp out
> therefore keeping the process alive is confused by the error
> message
>   "[188988.765862] Memory failure: 0x1840200: Killing
>    cellsrv:33395 due to hardware memory corruption"
> Slightly modify the error message to improve clarity.
> 
> Signed-off-by: Jane Chu <jane.chu@oracle.com>
> ---
>  mm/memory-failure.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index fc8b517..14de5e2 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -216,10 +216,9 @@ static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
>  	short addr_lsb = tk->size_shift;
>  	int ret;
>  
> -	pr_err("Memory failure: %#lx: Killing %s:%d due to hardware memory corruption\n",
> -		pfn, t->comm, t->pid);
> -
>  	if ((flags & MF_ACTION_REQUIRED) && t->mm == current->mm) {
> +		pr_err("Memory failure: %#lx: Killing %s:%d due to hardware memory "
> +			"corruption\n", pfn, t->comm, t->pid);

Minor nit, but the string shouldn't be split over multiple lines to
preserve grep-ability. In such a case it is usually considered OK to
exceed 80 characters for the line if needed.

>  		ret = force_sig_mceerr(BUS_MCEERR_AR, (void __user *)tk->addr,
>  				       addr_lsb, current);
>  	} else {
> @@ -229,6 +228,8 @@ static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
>  		 * This could cause a loop when the user sets SIGBUS
>  		 * to SIG_IGN, but hopefully no one will do that?
>  		 */
> +		pr_err("Memory failure: %#lx: Sending SIGBUS to %s:%d due to hardware "
> +			"memory corruption\n", pfn, t->comm, t->pid);
>  		ret = send_sig_mceerr(BUS_MCEERR_AO, (void __user *)tk->addr,
>  				      addr_lsb, t);  /* synchronous? */
>  	}

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] mm, memory-failure: clarify error message
  2019-05-17  4:48 ` Anshuman Khandual
@ 2019-05-20 10:21   ` Naoya Horiguchi
  2019-05-21  1:50     ` Jane Chu
  2019-05-21  1:53   ` Jane Chu
  1 sibling, 1 reply; 6+ messages in thread
From: Naoya Horiguchi @ 2019-05-20 10:21 UTC (permalink / raw)
  To: Anshuman Khandual; +Cc: Jane Chu, linux-mm, linux-kernel, linux-nvdimm

On Fri, May 17, 2019 at 10:18:02AM +0530, Anshuman Khandual wrote:
> 
> 
> On 05/17/2019 09:38 AM, Jane Chu wrote:
> > Some user who install SIGBUS handler that does longjmp out
> 
> What the longjmp about ? Are you referring to the mechanism of catching the
> signal which was registered ?

AFAIK, longjmp() might be useful for signal-based retrying, so highly
optimized applications like Oracle DB might want to utilize it to handle
memory errors in application level, I guess.

> 
> > therefore keeping the process alive is confused by the error
> > message
> >   "[188988.765862] Memory failure: 0x1840200: Killing
> >    cellsrv:33395 due to hardware memory corruption"
> 
> Its a valid point because those are two distinct actions.
> 
> > Slightly modify the error message to improve clarity.
> > 
> > Signed-off-by: Jane Chu <jane.chu@oracle.com>
> > ---
> >  mm/memory-failure.c | 7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> > 
> > diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> > index fc8b517..14de5e2 100644
> > --- a/mm/memory-failure.c
> > +++ b/mm/memory-failure.c
> > @@ -216,10 +216,9 @@ static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
> >  	short addr_lsb = tk->size_shift;
> >  	int ret;
> >  
> > -	pr_err("Memory failure: %#lx: Killing %s:%d due to hardware memory corruption\n",
> > -		pfn, t->comm, t->pid);
> > -
> >  	if ((flags & MF_ACTION_REQUIRED) && t->mm == current->mm) {
> > +		pr_err("Memory failure: %#lx: Killing %s:%d due to hardware memory "
> > +			"corruption\n", pfn, t->comm, t->pid);
> >  		ret = force_sig_mceerr(BUS_MCEERR_AR, (void __user *)tk->addr,
> >  				       addr_lsb, current);
> >  	} else {
> > @@ -229,6 +228,8 @@ static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
> >  		 * This could cause a loop when the user sets SIGBUS
> >  		 * to SIG_IGN, but hopefully no one will do that?
> >  		 */
> > +		pr_err("Memory failure: %#lx: Sending SIGBUS to %s:%d due to hardware "
> > +			"memory corruption\n", pfn, t->comm, t->pid);
> >  		ret = send_sig_mceerr(BUS_MCEERR_AO, (void __user *)tk->addr,
> >  				      addr_lsb, t);  /* synchronous? */
> 
> As both the pr_err() messages are very similar, could not we just switch between "Killing"
> and "Sending SIGBUS to" based on a variable e.g action_[kill|sigbus] evaluated previously
> with ((flags & MF_ACTION_REQUIRED) && t->mm == current->mm).

That might need additional if sentence, which I'm not sure worth doing.
I think that the simplest fix for the reported problem (a confusing message)
is like below:

	-	pr_err("Memory failure: %#lx: Killing %s:%d due to hardware memory corruption\n",
	+	pr_err("Memory failure: %#lx: Sending SIGBUS to %s:%d due to hardware memory corruption\n",
			pfn, t->comm, t->pid);

Or, if we have a good reason to separate the message for MF_ACTION_REQUIRED and
MF_ACTION_OPTIONAL, that might be OK.

Thanks,
Naoya Horiguchi

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] mm, memory-failure: clarify error message
  2019-05-20 10:21   ` Naoya Horiguchi
@ 2019-05-21  1:50     ` Jane Chu
  0 siblings, 0 replies; 6+ messages in thread
From: Jane Chu @ 2019-05-21  1:50 UTC (permalink / raw)
  To: Naoya Horiguchi, Anshuman Khandual; +Cc: linux-mm, linux-kernel, linux-nvdimm

Thanks Vishal and Naoya!

-jane

On 5/20/2019 3:21 AM, Naoya Horiguchi wrote:
> On Fri, May 17, 2019 at 10:18:02AM +0530, Anshuman Khandual wrote:
>>
>> On 05/17/2019 09:38 AM, Jane Chu wrote:
>>> Some user who install SIGBUS handler that does longjmp out
>> What the longjmp about ? Are you referring to the mechanism of catching the
>> signal which was registered ?
> AFAIK, longjmp() might be useful for signal-based retrying, so highly
> optimized applications like Oracle DB might want to utilize it to handle
> memory errors in application level, I guess.
>
>>> therefore keeping the process alive is confused by the error
>>> message
>>>    "[188988.765862] Memory failure: 0x1840200: Killing
>>>     cellsrv:33395 due to hardware memory corruption"
>> Its a valid point because those are two distinct actions.
>>
>>> Slightly modify the error message to improve clarity.
>>>
>>> Signed-off-by: Jane Chu <jane.chu@oracle.com>
>>> ---
>>>   mm/memory-failure.c | 7 ++++---
>>>   1 file changed, 4 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>>> index fc8b517..14de5e2 100644
>>> --- a/mm/memory-failure.c
>>> +++ b/mm/memory-failure.c
>>> @@ -216,10 +216,9 @@ static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
>>>   	short addr_lsb = tk->size_shift;
>>>   	int ret;
>>>   
>>> -	pr_err("Memory failure: %#lx: Killing %s:%d due to hardware memory corruption\n",
>>> -		pfn, t->comm, t->pid);
>>> -
>>>   	if ((flags & MF_ACTION_REQUIRED) && t->mm == current->mm) {
>>> +		pr_err("Memory failure: %#lx: Killing %s:%d due to hardware memory "
>>> +			"corruption\n", pfn, t->comm, t->pid);
>>>   		ret = force_sig_mceerr(BUS_MCEERR_AR, (void __user *)tk->addr,
>>>   				       addr_lsb, current);
>>>   	} else {
>>> @@ -229,6 +228,8 @@ static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
>>>   		 * This could cause a loop when the user sets SIGBUS
>>>   		 * to SIG_IGN, but hopefully no one will do that?
>>>   		 */
>>> +		pr_err("Memory failure: %#lx: Sending SIGBUS to %s:%d due to hardware "
>>> +			"memory corruption\n", pfn, t->comm, t->pid);
>>>   		ret = send_sig_mceerr(BUS_MCEERR_AO, (void __user *)tk->addr,
>>>   				      addr_lsb, t);  /* synchronous? */
>> As both the pr_err() messages are very similar, could not we just switch between "Killing"
>> and "Sending SIGBUS to" based on a variable e.g action_[kill|sigbus] evaluated previously
>> with ((flags & MF_ACTION_REQUIRED) && t->mm == current->mm).
> That might need additional if sentence, which I'm not sure worth doing.
> I think that the simplest fix for the reported problem (a confusing message)
> is like below:
>
> 	-	pr_err("Memory failure: %#lx: Killing %s:%d due to hardware memory corruption\n",
> 	+	pr_err("Memory failure: %#lx: Sending SIGBUS to %s:%d due to hardware memory corruption\n",
> 			pfn, t->comm, t->pid);
>
> Or, if we have a good reason to separate the message for MF_ACTION_REQUIRED and
> MF_ACTION_OPTIONAL, that might be OK.
>
> Thanks,
> Naoya Horiguchi


^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] mm, memory-failure: clarify error message
  2019-05-17  4:48 ` Anshuman Khandual
  2019-05-20 10:21   ` Naoya Horiguchi
@ 2019-05-21  1:53   ` Jane Chu
  1 sibling, 0 replies; 6+ messages in thread
From: Jane Chu @ 2019-05-21  1:53 UTC (permalink / raw)
  To: Anshuman Khandual, n-horiguchi, linux-mm, linux-kernel; +Cc: linux-nvdimm

On 5/16/2019 9:48 PM, Anshuman Khandual wrote:

> On 05/17/2019 09:38 AM, Jane Chu wrote:
>> Some user who install SIGBUS handler that does longjmp out
> What the longjmp about ? Are you referring to the mechanism of catching the
> signal which was registered ?

Yes.

thanks,
-jane


^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-05-21  1:53 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-05-17  4:08 [PATCH] mm, memory-failure: clarify error message Jane Chu
2019-05-17  4:48 ` Anshuman Khandual
2019-05-20 10:21   ` Naoya Horiguchi
2019-05-21  1:50     ` Jane Chu
2019-05-21  1:53   ` Jane Chu
2019-05-17 18:20 ` Verma, Vishal L

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