[3/3] pmem: Allow request_mem to fail, (CONFIG_BLK_DEV_PMEM_IGNORE_REQUEST_MEM_RET)
diff mbox

Message ID 54E1D36B.4000905@plexistor.com
State New, archived
Headers show

Commit Message

Boaz Harrosh Feb. 16, 2015, 11:24 a.m. UTC
With old Kernels there was a bug in x86 where any unknown
memory chip type would come up BUSY when calling
request_mem_region_exclusive().

So for pmem to work with old Kernels and real NvDIMM chips
we have a new Kconfig option CONFIG_BLK_DEV_PMEM_IGNORE_REQUEST_MEM_RET.

People have been running with hacked up pmem that will ignore
the return code from request_mem_region_exclusive. So here it is
official

Signed-off-by: Boaz Harrosh <boaz@plexistor.com>
---
 drivers/block/Kconfig | 12 ++++++++++++
 drivers/block/pmem.c  | 11 +++++++----
 2 files changed, 19 insertions(+), 4 deletions(-)

Comments

Ross Zwisler Feb. 17, 2015, 8:52 p.m. UTC | #1
On Mon, 2015-02-16 at 13:24 +0200, Boaz Harrosh wrote:
> With old Kernels there was a bug in x86 where any unknown
> memory chip type would come up BUSY when calling
> request_mem_region_exclusive().
> 
> So for pmem to work with old Kernels and real NvDIMM chips
> we have a new Kconfig option CONFIG_BLK_DEV_PMEM_IGNORE_REQUEST_MEM_RET.
> 
> People have been running with hacked up pmem that will ignore
> the return code from request_mem_region_exclusive. So here it is
> official
> 
> Signed-off-by: Boaz Harrosh <boaz@plexistor.com>

I'm confused - I thought that this behavior was fixed by patch 1/3?
With that patch this memory reservation should not fail, correct?

If so, why do we need this patch?

> ---
>  drivers/block/Kconfig | 12 ++++++++++++
>  drivers/block/pmem.c  | 11 +++++++----
>  2 files changed, 19 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
> index 3b3200f..10879b8 100644
> --- a/drivers/block/Kconfig
> +++ b/drivers/block/Kconfig
> @@ -430,6 +430,18 @@ config BLK_DEV_PMEM_USE_PAGES
>  	  to other devices in the system, then you must say "Yes" here.
>  	  If unsure leave as Yes.
>  
> +config BLK_DEV_PMEM_IGNORE_REQUEST_MEM_RET
> +	bool "Ignore the return code from request_mem_region_exclusive"
> +	depends on BLK_DEV_PMEM
> +	help
> +	  In Old Kernels type-12 Memory type which is used by NvDIMM
> +	  chips Comes out busy when calling request_mem_region_exclusive,
> +	  because of a bug.
> +	  If this option is set to "yes". The pmem will ignore the
> +	  failure, and continue as usual. If you have an old Kernel and
> +	  a real NvDIMM chip you must say yes here.
> +	  (Ignored if BLK_DEV_PMEM_USE_PAGES=y)
> +
>  config CDROM_PKTCDVD
>  	tristate "Packet writing on CD/DVD media"
>  	depends on !UML
> diff --git a/drivers/block/pmem.c b/drivers/block/pmem.c
> index 9eb7ffe..f84d033 100644
> --- a/drivers/block/pmem.c
> +++ b/drivers/block/pmem.c
> @@ -197,10 +197,12 @@ int pmem_mapmem(struct pmem_device *pmem)
>  
>  	res_mem = request_mem_region_exclusive(pmem->phys_addr, pmem->size,
>  					       "pmem");
> -	if (!res_mem) {
> +	if (unlikely(!res_mem)) {
>  		pr_warn("pmem: request_mem_region_exclusive phys=0x%llx size=0x%zx failed\n",
> -			   pmem->phys_addr, pmem->size);
> -		return -EINVAL;
> +			pmem->phys_addr, pmem->size);
> +#ifndef CONFIG_BLK_DEV_PMEM_IGNORE_REQUEST_MEM_RET
> +		return -EBUSY;
> +#endif
>  	}
>  
>  	pmem->virt_addr = ioremap_cache(pmem->phys_addr, pmem->size);
> @@ -211,7 +213,8 @@ int pmem_mapmem(struct pmem_device *pmem)
>  	return 0;
>  
>  out_release:
> -	release_mem_region(pmem->phys_addr, pmem->size);
> +	if (res_mem)
> +		release_mem_region(pmem->phys_addr, pmem->size);
>  	return err;
>  }
>
Boaz Harrosh Feb. 18, 2015, 9:58 a.m. UTC | #2
On 02/17/2015 10:52 PM, Ross Zwisler wrote:
> On Mon, 2015-02-16 at 13:24 +0200, Boaz Harrosh wrote:
>> With old Kernels there was a bug in x86 where any unknown
>> memory chip type would come up BUSY when calling
>> request_mem_region_exclusive().
>>
>> So for pmem to work with old Kernels and real NvDIMM chips
>> we have a new Kconfig option CONFIG_BLK_DEV_PMEM_IGNORE_REQUEST_MEM_RET.
>>
>> People have been running with hacked up pmem that will ignore
>> the return code from request_mem_region_exclusive. So here it is
>> official
>>
>> Signed-off-by: Boaz Harrosh <boaz@plexistor.com>
> 

Hi Ross, good morning

> I'm confused - I thought that this behavior was fixed by patch 1/3?
> With that patch this memory reservation should not fail, correct?
> 

Yes, I have tested it extensively and PATCH-1/3 fixes this problem
for sure.

> If so, why do we need this patch?
> 

I put in this patch for people that do-not-want/cannot compile their
own Kernel but have a need for pmem.c regardless. I will not include
this patch in the final submitted Kernel. Given that patch-1 gets
accepted before the merge of pmem.

Lets say that patch-1 and patch-3 are either or. A tree
that has 1/3 does not need 3/3, a tree that does not have 1/3 needs
3/3.

<>

Thanks
Boaz

Patch
diff mbox

diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index 3b3200f..10879b8 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -430,6 +430,18 @@  config BLK_DEV_PMEM_USE_PAGES
 	  to other devices in the system, then you must say "Yes" here.
 	  If unsure leave as Yes.
 
+config BLK_DEV_PMEM_IGNORE_REQUEST_MEM_RET
+	bool "Ignore the return code from request_mem_region_exclusive"
+	depends on BLK_DEV_PMEM
+	help
+	  In Old Kernels type-12 Memory type which is used by NvDIMM
+	  chips Comes out busy when calling request_mem_region_exclusive,
+	  because of a bug.
+	  If this option is set to "yes". The pmem will ignore the
+	  failure, and continue as usual. If you have an old Kernel and
+	  a real NvDIMM chip you must say yes here.
+	  (Ignored if BLK_DEV_PMEM_USE_PAGES=y)
+
 config CDROM_PKTCDVD
 	tristate "Packet writing on CD/DVD media"
 	depends on !UML
diff --git a/drivers/block/pmem.c b/drivers/block/pmem.c
index 9eb7ffe..f84d033 100644
--- a/drivers/block/pmem.c
+++ b/drivers/block/pmem.c
@@ -197,10 +197,12 @@  int pmem_mapmem(struct pmem_device *pmem)
 
 	res_mem = request_mem_region_exclusive(pmem->phys_addr, pmem->size,
 					       "pmem");
-	if (!res_mem) {
+	if (unlikely(!res_mem)) {
 		pr_warn("pmem: request_mem_region_exclusive phys=0x%llx size=0x%zx failed\n",
-			   pmem->phys_addr, pmem->size);
-		return -EINVAL;
+			pmem->phys_addr, pmem->size);
+#ifndef CONFIG_BLK_DEV_PMEM_IGNORE_REQUEST_MEM_RET
+		return -EBUSY;
+#endif
 	}
 
 	pmem->virt_addr = ioremap_cache(pmem->phys_addr, pmem->size);
@@ -211,7 +213,8 @@  int pmem_mapmem(struct pmem_device *pmem)
 	return 0;
 
 out_release:
-	release_mem_region(pmem->phys_addr, pmem->size);
+	if (res_mem)
+		release_mem_region(pmem->phys_addr, pmem->size);
 	return err;
 }