linux-next: manual merge of the edac-amd tree with the edac tree

linux-next: manual merge of the edac-amd tree with the edac tree

[Stephen Rothwell]

Hi Borislav,

Today's linux-next merge of the edac-amd tree got a conflict in:

  drivers/edac/edac_mc.c

between commit:

  ef91afa61088 ("edac: move documentation from edac_mc.c to edac_core.h")

from the edac tree and commit:

  c73e8833bec5 ("EDAC, mc: Fix locking around mc_devices list")

from the edac-amd tree.

I fixed it up (see below - there may be more fixes needed in
edac_core.h) and can carry the fix as necessary. This is now fixed as
far as linux-next is concerned, but any non trivial conflicts should be
mentioned to your upstream maintainer when your tree is submitted for
merging.  You may also want to consider cooperating with the maintainer
of the conflicting tree to minimise any particularly complex conflicts.

-- 
Cheers,
Stephen Rothwell

diff --cc drivers/edac/edac_mc.c
index d50653d36918,d2ea9c4f1824..000000000000
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@@ -470,6 -499,24 +470,17 @@@ static struct mem_ctl_info *__find_mci_
  
  	return NULL;
  }
+ 
 -/**
 - * find_mci_by_dev
 - *
 - *	scan list of controllers looking for the one that manages
 - *	the 'dev' device
 - * @dev: pointer to a struct device related with the MCI
 - */
+ struct mem_ctl_info *find_mci_by_dev(struct device *dev)
+ {
+ 	struct mem_ctl_info *ret;
+ 
+ 	mutex_lock(&mem_ctls_mutex);
+ 	ret = __find_mci_by_dev(dev);
+ 	mutex_unlock(&mem_ctls_mutex);
+ 
+ 	return ret;
+ }
  EXPORT_SYMBOL_GPL(find_mci_by_dev);
  
  /*
@@@ -599,10 -646,18 +610,12 @@@ static int del_mc_from_global_list(stru
  	return handlers;
  }
  
 -/**
 - * edac_mc_find: Search for a mem_ctl_info structure whose index is 'idx'.
 - *
 - * If found, return a pointer to the structure.
 - * Else return NULL.
 - */
  struct mem_ctl_info *edac_mc_find(int idx)
  {
+ 	struct mem_ctl_info *mci = NULL;
  	struct list_head *item;
- 	struct mem_ctl_info *mci;
+ 
+ 	mutex_lock(&mem_ctls_mutex);
  
  	list_for_each(item, &mc_devices) {
  		mci = list_entry(item, struct mem_ctl_info, link);

Re: linux-next: manual merge of the edac-amd tree with the edac tree

[Borislav Petkov]

On Mon, Nov 28, 2016 at 02:37:26PM +1100, Stephen Rothwell wrote:
> Hi Borislav,
> 
> Today's linux-next merge of the edac-amd tree got a conflict in:
> 
>   drivers/edac/edac_mc.c
> 
> between commit:
> 
>   ef91afa61088 ("edac: move documentation from edac_mc.c to edac_core.h")
> 
> from the edac tree and commit:
> 
>   c73e8833bec5 ("EDAC, mc: Fix locking around mc_devices list")
> 
> from the edac-amd tree.
> 
> I fixed it up (see below - there may be more fixes needed in
> edac_core.h) and can carry the fix as necessary. This is now fixed as
> far as linux-next is concerned, but any non trivial conflicts should be
> mentioned to your upstream maintainer when your tree is submitted for
> merging.  You may also want to consider cooperating with the maintainer
> of the conflicting tree to minimise any particularly complex conflicts.

Just one issue which has nothing to do with linux-next. There's still
that in ef91afa61088:

> +/**
> + * edac_mc_find: Search for a mem_ctl_info structure whose index is @idx.
> + *
> + * @idx: index to be seek
> + *
> + * If found, return a pointer to the structure.
> + * Else return NULL.
> + *
> + * Caller must hold mem_ctls_mutex.
> + */

That last sentence in the comment is not true anymore - edac_mc_find()
is grabbing the mutex itself as it should be. Mauro, please fix that in
your tree.

Thanks.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

Re: linux-next: manual merge of the edac-amd tree with the edac tree

[Mauro Carvalho Chehab]

Em Mon, 28 Nov 2016 09:27:35 +0100
Borislav Petkov <bp@alien8.de> escreveu:

> On Mon, Nov 28, 2016 at 02:37:26PM +1100, Stephen Rothwell wrote:
> > Hi Borislav,
> > 
> > Today's linux-next merge of the edac-amd tree got a conflict in:
> > 
> >   drivers/edac/edac_mc.c
> > 
> > between commit:
> > 
> >   ef91afa61088 ("edac: move documentation from edac_mc.c to edac_core.h")
> > 
> > from the edac tree and commit:
> > 
> >   c73e8833bec5 ("EDAC, mc: Fix locking around mc_devices list")
> > 
> > from the edac-amd tree.
> > 
> > I fixed it up (see below - there may be more fixes needed in
> > edac_core.h) and can carry the fix as necessary. This is now fixed as
> > far as linux-next is concerned, but any non trivial conflicts should be
> > mentioned to your upstream maintainer when your tree is submitted for
> > merging.  You may also want to consider cooperating with the maintainer
> > of the conflicting tree to minimise any particularly complex conflicts.  
> 
> Just one issue which has nothing to do with linux-next. There's still
> that in ef91afa61088:
> 
> > +/**
> > + * edac_mc_find: Search for a mem_ctl_info structure whose index is @idx.
> > + *
> > + * @idx: index to be seek
> > + *
> > + * If found, return a pointer to the structure.
> > + * Else return NULL.
> > + *
> > + * Caller must hold mem_ctls_mutex.
> > + */  
> 
> That last sentence in the comment is not true anymore - edac_mc_find()
> is grabbing the mutex itself as it should be. Mauro, please fix that in
> your tree.

Fixed. If you have a stable branch, I can rebase it on the top
of your patches, in order to avoid the confict at linux-next.

Regards,
Mauro

Re: linux-next: manual merge of the edac-amd tree with the edac tree

[Borislav Petkov]

On Wed, Nov 30, 2016 at 08:50:13AM -0200, Mauro Carvalho Chehab wrote:
> Fixed. If you have a stable branch, I can rebase it on the top
> of your patches, in order to avoid the confict at linux-next.

http://git.kernel.org/cgit/linux/kernel/git/bp/bp.git/log/?h=for-next

but with that fixed, shouldn't the merge work without a conflict?

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

Re: linux-next: manual merge of the edac-amd tree with the edac tree

[Mauro Carvalho Chehab]

Em Thu, 1 Dec 2016 11:48:46 +0100
Borislav Petkov <bp@alien8.de> escreveu:

> On Wed, Nov 30, 2016 at 08:50:13AM -0200, Mauro Carvalho Chehab wrote:
> > Fixed. If you have a stable branch, I can rebase it on the top
> > of your patches, in order to avoid the confict at linux-next.
> 
> http://git.kernel.org/cgit/linux/kernel/git/bp/bp.git/log/?h=for-next

Thanks!

> but with that fixed, shouldn't the merge work without a conflict?

Well, we're removing some lines from one file and adding them on another
one. Git is not smart enough to solve such conflicts automatically:

	CONFLICT (content): Merge conflict in drivers/edac/edac_mc.c
	Recorded preimage for 'drivers/edac/edac_mc.c'
	Automatic merge failed; fix conflicts and then commit the result.

Anyway, I rebased my work on the top of your branch. The conflict
is now gone:

	https://git.kernel.org/cgit/linux/kernel/git/mchehab/linux-edac.git/log/?h=linux_next

You can see the generated documentation at:
	https://mchehab.fedorapeople.org/kernel_docs/admin-guide/ras.html
	(user and admin guide)
and:
	https://mchehab.fedorapeople.org/kernel_docs/driver-api/edac.html
	(kernel API)

However, rebasing over your tree showed a new documentation gap:
	./include/linux/edac.h:144: warning: Enum value 'HW_EVENT_ERR_DEFERRED' not described in enum 'hw_event_mc_err_type'

With was introduced by this commit:

  commit d12a969ebbfcfc25853c4147d42b388f758e8784
  Author: Yazen Ghannam <Yazen.Ghannam@amd.com>
  Date:   Thu Nov 17 17:57:32 2016 -0500

    EDAC, amd64: Add Deferred Error type
    
    Currently, deferred errors are classified as correctable in EDAC. Add a
    new error type for deferred errors so that they are correctly reported
    to the user.
    
    Signed-off-by: Yazen Ghannam <Yazen.Ghannam@amd.com>
    Cc: Aravind Gopalakrishnan <aravindksg.lkml@gmail.com>
    Cc: linux-edac <linux-edac@vger.kernel.org>
    Link: http://lkml.kernel.org/r/1479423463-8536-7-git-send-email-Yazen.Ghannam@amd.com
    Signed-off-by: Borislav Petkov <bp@suse.de>


Yazen introduced a "deferred error" code (whatever it means), but didn't
document what's that. Unfortunately, the patch description is also
not clear enough about what a "deferred error" means or how userspace
is supposed to handle it.

Yazen,

Could you please send us a patch adding a proper description for this
new error code?

Thanks!
Mauro

Re: linux-next: manual merge of the edac-amd tree with the edac tree

[Yazen Ghannam]

On Thu, Dec 01, 2016 at 10:06:17AM -0200, Mauro Carvalho Chehab wrote:
> 
> However, rebasing over your tree showed a new documentation gap:
> 	./include/linux/edac.h:144: warning: Enum value 'HW_EVENT_ERR_DEFERRED' not described in enum 'hw_event_mc_err_type'
> 
> With was introduced by this commit:
> 
>   commit d12a969ebbfcfc25853c4147d42b388f758e8784
>   Author: Yazen Ghannam <Yazen.Ghannam@amd.com>
>   Date:   Thu Nov 17 17:57:32 2016 -0500
> 
>     EDAC, amd64: Add Deferred Error type
>     
>     Currently, deferred errors are classified as correctable in EDAC. Add a
>     new error type for deferred errors so that they are correctly reported
>     to the user.
>     
>     Signed-off-by: Yazen Ghannam <Yazen.Ghannam@amd.com>
>     Cc: Aravind Gopalakrishnan <aravindksg.lkml@gmail.com>
>     Cc: linux-edac <linux-edac@vger.kernel.org>
>     Link: http://lkml.kernel.org/r/1479423463-8536-7-git-send-email-Yazen.Ghannam@amd.com
>     Signed-off-by: Borislav Petkov <bp@suse.de>
> 
> 
> Yazen introduced a "deferred error" code (whatever it means), but didn't
> document what's that. Unfortunately, the patch description is also
> not clear enough about what a "deferred error" means or how userspace
> is supposed to handle it.
> 
> Yazen,
> 
> Could you please send us a patch adding a proper description for this
> new error code?
>

Hi Mauro,
A deferred error is an uncorrectable error whose handling can be
deferred, i.e. it's not urgent. This affects the system behavior, but
I'm now thinking that this shouldn't affect users' behavior. I think it
would be simpler to just classify deferred errors as uncorrectable
errors so that users treat them as such.

Boris,
Can we drop or revert commit d12a969ebbfc?

And can we apply a fixup like this to commit 713ad54675fd?

---
From: Yazen Ghannam <Yazen.Ghannam@amd.com>
Date: Thu, 1 Dec 2016 08:54:49 -0600
Subject: [PATCH] fixup! EDAC, amd64: Define and register UMC error decode
 function

Signed-off-by: Yazen Ghannam <Yazen.Ghannam@amd.com>
---
 drivers/edac/amd64_edac.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/edac/amd64_edac.c b/drivers/edac/amd64_edac.c
index 991b36c..245b9a0 100644
--- a/drivers/edac/amd64_edac.c
+++ b/drivers/edac/amd64_edac.c
@@ -2480,8 +2480,9 @@ static void decode_umc_error(int node_id, struct mce *m)
 
        memset(&err, 0, sizeof(err));
 
+       /* Log deferred errors as uncorrectable errors. */
        if (m->status & MCI_STATUS_DEFERRED)
-               ecc_type = 3;
+               ecc_type = 1;
 
        err.channel = find_umc_channel(pvt, m);
        if (err.channel < 0) {
-- 
2.7.4

---

Thanks,
Yazen

Re: linux-next: manual merge of the edac-amd tree with the edac tree

[Borislav Petkov]

On Thu, Dec 01, 2016 at 11:02:04AM -0500, Yazen Ghannam wrote:
> A deferred error is an uncorrectable error whose handling can be
> deferred, i.e. it's not urgent. This affects the system behavior, but
> I'm now thinking that this shouldn't affect users' behavior. I think it
> would be simpler to just classify deferred errors as uncorrectable
> errors so that users treat them as such.

Why would we want to lie about deferred errors being uncorrectable?

And I believe deferred errors can be handled differently like freeze the
process using the page instead of killing it. And so on...

Why aren't you simply adding the documentation about
HW_EVENT_ERR_DEFERRED and be done with it? The downstream path like
tracepoint and all can handle all that just fine.

> Boris,
> Can we drop or revert commit d12a969ebbfc?

No can do. It is a public branch and there's no touching it.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

Re: linux-next: manual merge of the edac-amd tree with the edac tree

[Yazen Ghannam]

On Thu, Dec 01, 2016 at 07:15:01PM +0100, Borislav Petkov wrote:
> On Thu, Dec 01, 2016 at 11:02:04AM -0500, Yazen Ghannam wrote:
> > A deferred error is an uncorrectable error whose handling can be
> > deferred, i.e. it's not urgent. This affects the system behavior, but
> > I'm now thinking that this shouldn't affect users' behavior. I think it
> > would be simpler to just classify deferred errors as uncorrectable
> > errors so that users treat them as such.
> 
> Why would we want to lie about deferred errors being uncorrectable?
>

They are uncorrectable errors that can be handled differently. If you
can't handle them then there's not much difference.
 
> And I believe deferred errors can be handled differently like freeze the
> process using the page instead of killing it. And so on...
> 

If deferred errors can be handled differently in userspace, then you're
right we should maintain the distinction. I was thinking we'd only
handle them in the kernel.

> Why aren't you simply adding the documentation about
> HW_EVENT_ERR_DEFERRED and be done with it? The downstream path like
> tracepoint and all can handle all that just fine.
> 

Okay, will do.

> > Boris,
> > Can we drop or revert commit d12a969ebbfc?
> 
> No can do. It is a public branch and there's no touching it.
> 

Okay, got it.

Thanks,
Yazen

[PATCH] EDAC: Document HW_EVENT_ERR_DEFERRED type

[Yazen Ghannam]

Add a description of the HW_EVENT_ERR_DEFERRED type that wasn't included
with commit d12a969ebbfc ("EDAC, amd64: Add Deferred Error type").

Cc: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Cc: Borislav Petkov <bp@suse.de>
Signed-off-by: Yazen Ghannam <Yazen.Ghannam@amd.com>
---
 include/linux/edac.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/linux/edac.h b/include/linux/edac.h
index cb56dcb..43cd51d 100644
--- a/include/linux/edac.h
+++ b/include/linux/edac.h
@@ -128,6 +128,12 @@ enum dev_type {
  *				fatal (maybe it is on an unused memory area,
  *				or the memory controller could recover from
  *				it for example, by re-trying the operation).
+ * @HW_EVENT_ERR_DEFERRED:	Deferred Error - Indicates an uncorrectable
+ *				error whose handling is not urgent. This could
+ *				be due to hardware data poisoning where the
+ *				system can continue operation until the poisoned
+ *				data is consumed. Preemptive measures may also
+ *				be taken, e.g. offlining pages, etc.
  * @HW_EVENT_ERR_FATAL:		Fatal Error - Uncorrected error that could not
  *				be recovered.
  */
-- 
2.7.4

Re: [PATCH] EDAC: Document HW_EVENT_ERR_DEFERRED type

[Borislav Petkov]

On Thu, Dec 01, 2016 at 02:24:53PM -0600, Yazen Ghannam wrote:
> Add a description of the HW_EVENT_ERR_DEFERRED type that wasn't included
> with commit d12a969ebbfc ("EDAC, amd64: Add Deferred Error type").
> 
> Cc: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
> Cc: Borislav Petkov <bp@suse.de>
> Signed-off-by: Yazen Ghannam <Yazen.Ghannam@amd.com>
> ---
>  include/linux/edac.h | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/include/linux/edac.h b/include/linux/edac.h
> index cb56dcb..43cd51d 100644
> --- a/include/linux/edac.h
> +++ b/include/linux/edac.h
> @@ -128,6 +128,12 @@ enum dev_type {
>   *				fatal (maybe it is on an unused memory area,
>   *				or the memory controller could recover from
>   *				it for example, by re-trying the operation).
> + * @HW_EVENT_ERR_DEFERRED:	Deferred Error - Indicates an uncorrectable
> + *				error whose handling is not urgent. This could
> + *				be due to hardware data poisoning where the
> + *				system can continue operation until the poisoned
> + *				data is consumed. Preemptive measures may also
> + *				be taken, e.g. offlining pages, etc.
>   * @HW_EVENT_ERR_FATAL:		Fatal Error - Uncorrected error that could not
>   *				be recovered.
>   */
> -- 

Acked-by: Borislav Petkov <bp@suse.de>

Mauro, are you taking this through your tree or should I?

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
-- 

Re: [PATCH] EDAC: Document HW_EVENT_ERR_DEFERRED type

[Mauro Carvalho Chehab]

Em Thu, 1 Dec 2016 21:27:42 +0100
Borislav Petkov <bp@suse.de> escreveu:

> On Thu, Dec 01, 2016 at 02:24:53PM -0600, Yazen Ghannam wrote:
> > Add a description of the HW_EVENT_ERR_DEFERRED type that wasn't included
> > with commit d12a969ebbfc ("EDAC, amd64: Add Deferred Error type").

Thanks for the patch!

> > 
> > Cc: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
> > Cc: Borislav Petkov <bp@suse.de>
> > Signed-off-by: Yazen Ghannam <Yazen.Ghannam@amd.com>
> > ---
> >  include/linux/edac.h | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/include/linux/edac.h b/include/linux/edac.h
> > index cb56dcb..43cd51d 100644
> > --- a/include/linux/edac.h
> > +++ b/include/linux/edac.h
> > @@ -128,6 +128,12 @@ enum dev_type {
> >   *				fatal (maybe it is on an unused memory area,
> >   *				or the memory controller could recover from
> >   *				it for example, by re-trying the operation).
> > + * @HW_EVENT_ERR_DEFERRED:	Deferred Error - Indicates an uncorrectable
> > + *				error whose handling is not urgent. This could
> > + *				be due to hardware data poisoning where the
> > + *				system can continue operation until the poisoned
> > + *				data is consumed. Preemptive measures may also
> > + *				be taken, e.g. offlining pages, etc.

I'm wandering if DEFERRED is the best name here... Maybe it could be
called, instead HW_EVENT_ERR_NON_URGENT or something like that.

Anyway, the description itself looks good.

> >   * @HW_EVENT_ERR_FATAL:		Fatal Error - Uncorrected error that could not
> >   *				be recovered.
> >   */
> > --   
> 
> Acked-by: Borislav Petkov <bp@suse.de>
> 
> Mauro, are you taking this through your tree or should I?

Boris, yeah, I can take care on it. I'll send my pull request
after yours, to avoid any issues.

-- 
Thanks,
Mauro

Re: [PATCH] EDAC: Document HW_EVENT_ERR_DEFERRED type

[Borislav Petkov]

On Thu, Dec 01, 2016 at 07:36:45PM -0200, Mauro Carvalho Chehab wrote:
> I'm wandering if DEFERRED is the best name here... Maybe it could be
> called, instead HW_EVENT_ERR_NON_URGENT or something like that.

No, that's what the error is called in the hw documentation. It is
really a *deferred* uncorrectable error. Deferred in the sense that it
hasn't been consumed yet.

> Boris, yeah, I can take care on it. I'll send my pull request
> after yours, to avoid any issues.

Ok, cool.

Thanks.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
-- 

Re: [PATCH] EDAC: Document HW_EVENT_ERR_DEFERRED type

[Mauro Carvalho Chehab]

Em Thu, 1 Dec 2016 22:49:18 +0100
Borislav Petkov <bp@suse.de> escreveu:

> On Thu, Dec 01, 2016 at 07:36:45PM -0200, Mauro Carvalho Chehab wrote:
> > I'm wandering if DEFERRED is the best name here... Maybe it could be
> > called, instead HW_EVENT_ERR_NON_URGENT or something like that.  
> 
> No, that's what the error is called in the hw documentation. It is
> really a *deferred* uncorrectable error. Deferred in the sense that it
> hasn't been consumed yet.

OK.

> > Boris, yeah, I can take care on it. I'll send my pull request
> > after yours, to avoid any issues.  
> 
> Ok, cool.
> 
> Thanks.

Patch applied.

Thanks!
Mauro