[v1,5/8] hv_balloon: mark inflated pages PG_offline
diff mbox series

Message ID 20181119101616.8901-6-david@redhat.com
State In Next
Commit b9a51ab2797e8e35cb04461e9480e2c20b9e2514
Headers show
Series
  • [v1,1/8] mm: balloon: update comment about isolation/migration/compaction
Related show

Commit Message

David Hildenbrand Nov. 19, 2018, 10:16 a.m. UTC
Mark inflated and never onlined pages PG_offline, to tell the world that
the content is stale and should not be dumped.

Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Kairui Song <kasong@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 drivers/hv/hv_balloon.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

Comments

Pankaj Gupta Nov. 20, 2018, 8:45 a.m. UTC | #1
Hi David,

> 
> Mark inflated and never onlined pages PG_offline, to tell the world that
> the content is stale and should not be dumped.
> 
> Cc: "K. Y. Srinivasan" <kys@microsoft.com>
> Cc: Haiyang Zhang <haiyangz@microsoft.com>
> Cc: Stephen Hemminger <sthemmin@microsoft.com>
> Cc: Kairui Song <kasong@redhat.com>
> Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Matthew Wilcox <willy@infradead.org>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  drivers/hv/hv_balloon.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
> index 211f3fe3a038..47719862e57f 100644
> --- a/drivers/hv/hv_balloon.c
> +++ b/drivers/hv/hv_balloon.c
> @@ -681,8 +681,13 @@ static struct notifier_block hv_memory_nb = {
>  /* Check if the particular page is backed and can be onlined and online it.
>  */
>  static void hv_page_online_one(struct hv_hotadd_state *has, struct page *pg)
>  {
> -	if (!has_pfn_is_backed(has, page_to_pfn(pg)))
> +	if (!has_pfn_is_backed(has, page_to_pfn(pg))) {
> +		if (!PageOffline(pg))
> +			__SetPageOffline(pg);
>  		return;
> +	}
> +	if (PageOffline(pg))
> +		__ClearPageOffline(pg);
>  
>  	/* This frame is currently backed; online the page. */
>  	__online_page_set_limits(pg);
> @@ -1201,6 +1206,7 @@ static void free_balloon_pages(struct hv_dynmem_device
> *dm,
>  
>  	for (i = 0; i < num_pages; i++) {
>  		pg = pfn_to_page(i + start_frame);
> +		__ClearPageOffline(pg);

Just thinking, do we need to care for clearing PageOffline flag before freeing
a balloon'd page?

Thanks,
Pankaj

>  		__free_page(pg);
>  		dm->num_pages_ballooned--;
>  	}
> @@ -1213,7 +1219,7 @@ static unsigned int alloc_balloon_pages(struct
> hv_dynmem_device *dm,
>  					struct dm_balloon_response *bl_resp,
>  					int alloc_unit)
>  {
> -	unsigned int i = 0;
> +	unsigned int i, j;
>  	struct page *pg;
>  
>  	if (num_pages < alloc_unit)
> @@ -1245,6 +1251,10 @@ static unsigned int alloc_balloon_pages(struct
> hv_dynmem_device *dm,
>  		if (alloc_unit != 1)
>  			split_page(pg, get_order(alloc_unit << PAGE_SHIFT));
>  
> +		/* mark all pages offline */
> +		for (j = 0; j < (1 << get_order(alloc_unit << PAGE_SHIFT)); j++)
> +			__SetPageOffline(pg + j);
> +
>  		bl_resp->range_count++;
>  		bl_resp->range_array[i].finfo.start_page =
>  			page_to_pfn(pg);
> --
> 2.17.2
> 
>
David Hildenbrand Nov. 20, 2018, 8:49 a.m. UTC | #2
On 20.11.18 09:45, Pankaj Gupta wrote:
> 
> Hi David,
> 
>>
>> Mark inflated and never onlined pages PG_offline, to tell the world that
>> the content is stale and should not be dumped.
>>
>> Cc: "K. Y. Srinivasan" <kys@microsoft.com>
>> Cc: Haiyang Zhang <haiyangz@microsoft.com>
>> Cc: Stephen Hemminger <sthemmin@microsoft.com>
>> Cc: Kairui Song <kasong@redhat.com>
>> Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Matthew Wilcox <willy@infradead.org>
>> Cc: Michal Hocko <mhocko@suse.com>
>> Cc: "Michael S. Tsirkin" <mst@redhat.com>
>> Signed-off-by: David Hildenbrand <david@redhat.com>
>> ---
>>  drivers/hv/hv_balloon.c | 14 ++++++++++++--
>>  1 file changed, 12 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
>> index 211f3fe3a038..47719862e57f 100644
>> --- a/drivers/hv/hv_balloon.c
>> +++ b/drivers/hv/hv_balloon.c
>> @@ -681,8 +681,13 @@ static struct notifier_block hv_memory_nb = {
>>  /* Check if the particular page is backed and can be onlined and online it.
>>  */
>>  static void hv_page_online_one(struct hv_hotadd_state *has, struct page *pg)
>>  {
>> -	if (!has_pfn_is_backed(has, page_to_pfn(pg)))
>> +	if (!has_pfn_is_backed(has, page_to_pfn(pg))) {
>> +		if (!PageOffline(pg))
>> +			__SetPageOffline(pg);
>>  		return;
>> +	}
>> +	if (PageOffline(pg))
>> +		__ClearPageOffline(pg);
>>  
>>  	/* This frame is currently backed; online the page. */
>>  	__online_page_set_limits(pg);
>> @@ -1201,6 +1206,7 @@ static void free_balloon_pages(struct hv_dynmem_device
>> *dm,
>>  
>>  	for (i = 0; i < num_pages; i++) {
>>  		pg = pfn_to_page(i + start_frame);
>> +		__ClearPageOffline(pg);
> 
> Just thinking, do we need to care for clearing PageOffline flag before freeing
> a balloon'd page?

Yes we have to otherwise the code will crash when trying to set PageBuddy.

(only one page type at a time may be set right now, and it makes sense.
A page that is offline cannot e.g. be a buddy page)

So PageOffline is completely managed by the page owner.

> 
> Thanks,
> Pankaj
Pankaj Gupta Nov. 20, 2018, 9:37 a.m. UTC | #3
> >> ---
> >>  drivers/hv/hv_balloon.c | 14 ++++++++++++--
> >>  1 file changed, 12 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
> >> index 211f3fe3a038..47719862e57f 100644
> >> --- a/drivers/hv/hv_balloon.c
> >> +++ b/drivers/hv/hv_balloon.c
> >> @@ -681,8 +681,13 @@ static struct notifier_block hv_memory_nb = {
> >>  /* Check if the particular page is backed and can be onlined and online
> >>  it.
> >>  */
> >>  static void hv_page_online_one(struct hv_hotadd_state *has, struct page
> >>  *pg)
> >>  {
> >> -	if (!has_pfn_is_backed(has, page_to_pfn(pg)))
> >> +	if (!has_pfn_is_backed(has, page_to_pfn(pg))) {
> >> +		if (!PageOffline(pg))
> >> +			__SetPageOffline(pg);
> >>  		return;
> >> +	}
> >> +	if (PageOffline(pg))
> >> +		__ClearPageOffline(pg);
> >>  
> >>  	/* This frame is currently backed; online the page. */
> >>  	__online_page_set_limits(pg);
> >> @@ -1201,6 +1206,7 @@ static void free_balloon_pages(struct
> >> hv_dynmem_device
> >> *dm,
> >>  
> >>  	for (i = 0; i < num_pages; i++) {
> >>  		pg = pfn_to_page(i + start_frame);
> >> +		__ClearPageOffline(pg);
> > 
> > Just thinking, do we need to care for clearing PageOffline flag before
> > freeing
> > a balloon'd page?
> 
> Yes we have to otherwise the code will crash when trying to set PageBuddy.
> 
> (only one page type at a time may be set right now, and it makes sense.
> A page that is offline cannot e.g. be a buddy page)

o.k
> 
> So PageOffline is completely managed by the page owner.

Makes sense. Thanks for explaining.

Pankaj
> 
> > 
> > Thanks,
> > Pankaj
> 
> 
> --
> 
> Thanks,
> 
> David / dhildenb
>
Pankaj Gupta Nov. 21, 2018, 1:04 a.m. UTC | #4
> > >> ---
> > >>  drivers/hv/hv_balloon.c | 14 ++++++++++++--
> > >>  1 file changed, 12 insertions(+), 2 deletions(-)
> > >>
> > >> diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
> > >> index 211f3fe3a038..47719862e57f 100644
> > >> --- a/drivers/hv/hv_balloon.c
> > >> +++ b/drivers/hv/hv_balloon.c
> > >> @@ -681,8 +681,13 @@ static struct notifier_block hv_memory_nb = {
> > >>  /* Check if the particular page is backed and can be onlined and online
> > >>  it.
> > >>  */
> > >>  static void hv_page_online_one(struct hv_hotadd_state *has, struct page
> > >>  *pg)
> > >>  {
> > >> -	if (!has_pfn_is_backed(has, page_to_pfn(pg)))
> > >> +	if (!has_pfn_is_backed(has, page_to_pfn(pg))) {
> > >> +		if (!PageOffline(pg))
> > >> +			__SetPageOffline(pg);
> > >>  		return;
> > >> +	}
> > >> +	if (PageOffline(pg))
> > >> +		__ClearPageOffline(pg);
> > >>  
> > >>  	/* This frame is currently backed; online the page. */
> > >>  	__online_page_set_limits(pg);
> > >> @@ -1201,6 +1206,7 @@ static void free_balloon_pages(struct
> > >> hv_dynmem_device
> > >> *dm,
> > >>  
> > >>  	for (i = 0; i < num_pages; i++) {
> > >>  		pg = pfn_to_page(i + start_frame);
> > >> +		__ClearPageOffline(pg);
> > > 
> > > Just thinking, do we need to care for clearing PageOffline flag before
> > > freeing
> > > a balloon'd page?
> > 
> > Yes we have to otherwise the code will crash when trying to set PageBuddy.
> > 
> > (only one page type at a time may be set right now, and it makes sense.
> > A page that is offline cannot e.g. be a buddy page)
> 
> o.k
> > 
> > So PageOffline is completely managed by the page owner.
> 
> Makes sense. Thanks for explaining.

Looks good to me.

Acked-by: Pankaj gupta <pagupta@redhat.com>

Patch
diff mbox series

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index 211f3fe3a038..47719862e57f 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -681,8 +681,13 @@  static struct notifier_block hv_memory_nb = {
 /* Check if the particular page is backed and can be onlined and online it. */
 static void hv_page_online_one(struct hv_hotadd_state *has, struct page *pg)
 {
-	if (!has_pfn_is_backed(has, page_to_pfn(pg)))
+	if (!has_pfn_is_backed(has, page_to_pfn(pg))) {
+		if (!PageOffline(pg))
+			__SetPageOffline(pg);
 		return;
+	}
+	if (PageOffline(pg))
+		__ClearPageOffline(pg);
 
 	/* This frame is currently backed; online the page. */
 	__online_page_set_limits(pg);
@@ -1201,6 +1206,7 @@  static void free_balloon_pages(struct hv_dynmem_device *dm,
 
 	for (i = 0; i < num_pages; i++) {
 		pg = pfn_to_page(i + start_frame);
+		__ClearPageOffline(pg);
 		__free_page(pg);
 		dm->num_pages_ballooned--;
 	}
@@ -1213,7 +1219,7 @@  static unsigned int alloc_balloon_pages(struct hv_dynmem_device *dm,
 					struct dm_balloon_response *bl_resp,
 					int alloc_unit)
 {
-	unsigned int i = 0;
+	unsigned int i, j;
 	struct page *pg;
 
 	if (num_pages < alloc_unit)
@@ -1245,6 +1251,10 @@  static unsigned int alloc_balloon_pages(struct hv_dynmem_device *dm,
 		if (alloc_unit != 1)
 			split_page(pg, get_order(alloc_unit << PAGE_SHIFT));
 
+		/* mark all pages offline */
+		for (j = 0; j < (1 << get_order(alloc_unit << PAGE_SHIFT)); j++)
+			__SetPageOffline(pg + j);
+
 		bl_resp->range_count++;
 		bl_resp->range_array[i].finfo.start_page =
 			page_to_pfn(pg);