[v23,8/9] mm: memory_hotplug: disable memmap_on_memory when hugetlb_free_vmemmap enabled

Commit Message

Muchun Song May 10, 2021, 3 a.m. UTC

The parameter of memory_hotplug.memmap_on_memory is not compatible with
hugetlb_free_vmemmap. So disable it when hugetlb_free_vmemmap is
enabled.

Signed-off-by: Muchun Song <[e-mail]>
Acked-by: Mike Kravetz <[e-mail]>
---
 Documentation/admin-guide/kernel-parameters.txt | 8 ++++++++
 drivers/acpi/acpi_memhotplug.c                  | 1 +
 mm/memory_hotplug.c                             | 1 +
 3 files changed, 10 insertions(+)

Comments

Oscar Salvador May 10, 2021, 10:08 a.m. UTC | #1

On Mon, May 10, 2021 at 11:00:26AM +0800, Muchun Song wrote:
> diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
> index 8cc195c4c861..0d7f595ee441 100644
> --- a/drivers/acpi/acpi_memhotplug.c
> +++ b/drivers/acpi/acpi_memhotplug.c
> @@ -15,6 +15,7 @@
>  #include <linux/acpi.h>
>  #include <linux/memory.h>
>  #include <linux/memory_hotplug.h>
> +#include <linux/hugetlb.h>
>  
>  #include "internal.h"

Uhm, I am confused.
Why do we need this here? AFAICS, we do not.

The function is in memory_hotplug.c, and that alrady has that include.
What am I missing?

Muchun Song May 10, 2021, 10:33 a.m. UTC | #2

On Mon, May 10, 2021 at 6:08 PM Oscar Salvador <[e-mail]> wrote:
>
> On Mon, May 10, 2021 at 11:00:26AM +0800, Muchun Song wrote:
> > diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
> > index 8cc195c4c861..0d7f595ee441 100644
> > --- a/drivers/acpi/acpi_memhotplug.c
> > +++ b/drivers/acpi/acpi_memhotplug.c
> > @@ -15,6 +15,7 @@
> >  #include <linux/acpi.h>
> >  #include <linux/memory.h>
> >  #include <linux/memory_hotplug.h>
> > +#include <linux/hugetlb.h>
> >
> >  #include "internal.h"
>
> Uhm, I am confused.
> Why do we need this here? AFAICS, we do not.
>
> The function is in memory_hotplug.c, and that alrady has that include.
> What am I missing?

You are right. That include is redundant. I will remove it
from acpi_memhotplug.c. Thanks Oscar.

>
>
> --
> Oscar Salvador
> SUSE L3

Patch

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 3cc19cb78b85..8181345e996a 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1638,6 +1638,10 @@ 
 			on:  enable the feature
 			off: disable the feature
 
+			This is not compatible with memory_hotplug.memmap_on_memory.
+			If both parameters are enabled, hugetlb_free_vmemmap takes
+			precedence over memory_hotplug.memmap_on_memory.
+
 	hung_task_panic=
 			[KNL] Should the hung task detector generate panics.
 			Format: 0 | 1
@@ -2904,6 +2908,10 @@ 
 			Note that even when enabled, there are a few cases where
 			the feature is not effective.
 
+			This is not compatible with hugetlb_free_vmemmap. If
+			both parameters are enabled, hugetlb_free_vmemmap takes
+			precedence over memory_hotplug.memmap_on_memory.
+
 	memtest=	[KNL,X86,ARM,PPC,RISCV] Enable memtest
 			Format: <integer>
 			default : 0 <disable>
diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index 8cc195c4c861..0d7f595ee441 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -15,6 +15,7 @@ 
 #include <linux/acpi.h>
 #include <linux/memory.h>
 #include <linux/memory_hotplug.h>
+#include <linux/hugetlb.h>
 
 #include "internal.h"
 
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 16b3a7a1db8c..6512e6f641bb 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1052,6 +1052,7 @@  bool mhp_supports_memmap_on_memory(unsigned long size)
 	 *       populate a single PMD.
 	 */
 	return memmap_on_memory &&
+	       !is_hugetlb_free_vmemmap_enabled() &&
 	       IS_ENABLED(CONFIG_MHP_MEMMAP_ON_MEMORY) &&
 	       size == memory_block_size_bytes() &&
 	       IS_ALIGNED(vmemmap_size, PMD_SIZE) &&