Re: [PATCH 3/6] mm: remove return value from init_currently_empty_zone

[Michal Hocko]

On Mon 03-04-17 16:22:32, Reza Arbab wrote:
> On Thu, Mar 30, 2017 at 01:54:51PM +0200, Michal Hocko wrote:
> >init_currently_empty_zone doesn't have any error to return yet it is
> >still an int and callers try to be defensive and try to handle potential
> >error. Remove this nonsense and simplify all callers.
> 
> Semi-related; arch_remove_memory() returns int, but callers ignore it.
> 
> Is that worth cleaning up? If so, should the implementations be simplified,
> or should we maybe do a pr_error() or something with it?

No, pr_error is not really helpful. Either that path can fail and we
should handle it properly - which will be hard because remove_memory
cannot handle that or we should just make arch_remove_memory
non-failing. I have a suspicion that this path doesn't really fail
in fact. This requires a deeper inspection though. I've put that on my
todo list.

Thanks!
-- 
Michal Hocko
SUSE Labs

Re: [PATCH 3/6] mm: remove return value from init_currently_empty_zone

[Michal Hocko]

On Mon 03-04-17 16:22:32, Reza Arbab wrote:
> On Thu, Mar 30, 2017 at 01:54:51PM +0200, Michal Hocko wrote:
> >init_currently_empty_zone doesn't have any error to return yet it is
> >still an int and callers try to be defensive and try to handle potential
> >error. Remove this nonsense and simplify all callers.
> 
> Semi-related; arch_remove_memory() returns int, but callers ignore it.
> 
> Is that worth cleaning up? If so, should the implementations be simplified,
> or should we maybe do a pr_error() or something with it?

No, pr_error is not really helpful. Either that path can fail and we
should handle it properly - which will be hard because remove_memory
cannot handle that or we should just make arch_remove_memory
non-failing. I have a suspicion that this path doesn't really fail
in fact. This requires a deeper inspection though. I've put that on my
todo list.

Thanks!
-- 
Michal Hocko
SUSE Labs

Re: [PATCH 3/6] mm: remove return value from init_currently_empty_zone

[Reza Arbab]

On Thu, Mar 30, 2017 at 01:54:51PM +0200, Michal Hocko wrote:

init_currently_empty_zone doesn't have any error to return yet it is
still an int and callers try to be defensive and try to handle potential
error. Remove this nonsense and simplify all callers.


Semi-related; arch_remove_memory() returns int, but callers ignore it.

Is that worth cleaning up? If so, should the implementations be 
simplified, or should we maybe do a pr_error() or something with it?


--
Reza Arbab

Re: [PATCH 3/6] mm: remove return value from init_currently_empty_zone

[Reza Arbab]

On Thu, Mar 30, 2017 at 01:54:51PM +0200, Michal Hocko wrote:

init_currently_empty_zone doesn't have any error to return yet it is
still an int and callers try to be defensive and try to handle potential
error. Remove this nonsense and simplify all callers.


Semi-related; arch_remove_memory() returns int, but callers ignore it.

Is that worth cleaning up? If so, should the implementations be 
simplified, or should we maybe do a pr_error() or something with it?


--
Reza Arbab

Re: [PATCH 3/6] mm: remove return value from init_currently_empty_zone

[Michal Hocko]

Fixed screw ups during the initial patch split up as per Hillf
---
>From a53c465b8f8046c6e6886dc3c17945238e63ee7c Mon Sep 17 00:00:00 2001
From: Michal Hocko 
Date: Wed, 29 Mar 2017 15:17:48 +0200
Subject: [PATCH] mm: remove return value from init_currently_empty_zone

init_currently_empty_zone doesn't have any error to return yet it is
still an int and callers try to be defensive and try to handle potential
error. Remove this nonsense and simplify all callers.

This patch shouldn't have any visible effect

Signed-off-by: Michal Hocko 
---
 include/linux/mmzone.h |  2 +-
 mm/memory_hotplug.c| 23 +--
 mm/page_alloc.c|  8 ++--
 3 files changed, 8 insertions(+), 25 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 3bac3ed71c7a..6973a3e6ad73 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -762,7 +762,7 @@ enum memmap_context {
MEMMAP_EARLY,
MEMMAP_HOTPLUG,
 };
-extern int init_currently_empty_zone(struct zone *zone, unsigned long 
start_pfn,
+extern void init_currently_empty_zone(struct zone *zone, unsigned long 
start_pfn,
 unsigned long size);
 
 extern void lruvec_init(struct lruvec *lruvec);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 699f5a2a8efd..1d55e5ec943f 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -343,27 +343,20 @@ static void fix_zone_id(struct zone *zone, unsigned long 
start_pfn,
set_page_links(pfn_to_page(pfn), zid, nid, pfn);
 }
 
-/* Can fail with -ENOMEM from allocating a wait table with vmalloc() or
- * alloc_bootmem_node_nopanic()/memblock_virt_alloc_node_nopanic() */
-static int __ref ensure_zone_is_initialized(struct zone *zone,
+static void __ref ensure_zone_is_initialized(struct zone *zone,
unsigned long start_pfn, unsigned long num_pages)
 {
if (zone_is_empty(zone))
-   return init_currently_empty_zone(zone, start_pfn, num_pages);
-
-   return 0;
+   init_currently_empty_zone(zone, start_pfn, num_pages);
 }
 
 static int __meminit move_pfn_range_left(struct zone *z1, struct zone *z2,
unsigned long start_pfn, unsigned long end_pfn)
 {
-   int ret;
unsigned long flags;
unsigned long z1_start_pfn;
 
-   ret = ensure_zone_is_initialized(z1, start_pfn, end_pfn - start_pfn);
-   if (ret)
-   return ret;
+   ensure_zone_is_initialized(z1, start_pfn, end_pfn - start_pfn);
 
pgdat_resize_lock(z1->zone_pgdat, );
 
@@ -399,13 +392,10 @@ static int __meminit move_pfn_range_left(struct zone *z1, 
struct zone *z2,
 static int __meminit move_pfn_range_right(struct zone *z1, struct zone *z2,
unsigned long start_pfn, unsigned long end_pfn)
 {
-   int ret;
unsigned long flags;
unsigned long z2_end_pfn;
 
-   ret = ensure_zone_is_initialized(z2, start_pfn, end_pfn - start_pfn);
-   if (ret)
-   return ret;
+   ensure_zone_is_initialized(z2, start_pfn, end_pfn - start_pfn);
 
pgdat_resize_lock(z1->zone_pgdat, );
 
@@ -476,12 +466,9 @@ static int __meminit __add_zone(struct zone *zone, 
unsigned long phys_start_pfn)
int nid = pgdat->node_id;
int zone_type;
unsigned long flags, pfn;
-   int ret;
 
zone_type = zone - pgdat->node_zones;
-   ret = ensure_zone_is_initialized(zone, phys_start_pfn, nr_pages);
-   if (ret)
-   return ret;
+   ensure_zone_is_initialized(zone, phys_start_pfn, nr_pages);
 
pgdat_resize_lock(zone->zone_pgdat, );
grow_zone_span(zone, phys_start_pfn, phys_start_pfn + nr_pages);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 756353d1e293..c6127f1a62e9 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5518,7 +5518,7 @@ static __meminit void zone_pcp_init(struct zone *zone)
 zone_batchsize(zone));
 }
 
-int __meminit init_currently_empty_zone(struct zone *zone,
+void __meminit init_currently_empty_zone(struct zone *zone,
unsigned long zone_start_pfn,
unsigned long size)
 {
@@ -5535,8 +5535,6 @@ int __meminit init_currently_empty_zone(struct zone *zone,
zone_start_pfn, (zone_start_pfn + size));
 
zone_init_free_lists(zone);
-
-   return 0;
 }
 
 #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
@@ -5999,7 +5997,6 @@ static void __paginginit free_area_init_core(struct 
pglist_data *pgdat)
 {
enum zone_type j;
int nid = pgdat->node_id;
-   int ret;
 
pgdat_resize_init(pgdat);
 #ifdef CONFIG_NUMA_BALANCING
@@ -6081,8 +6078,7 @@ static void __paginginit free_area_init_core(struct 
pglist_data *pgdat)
 
set_pageblock_order();
setup_usemap(pgdat, zone, zone_start_pfn, size);
-   ret = 

Re: [PATCH 3/6] mm: remove return value from init_currently_empty_zone

[Michal Hocko]

Fixed screw ups during the initial patch split up as per Hillf
---
>From a53c465b8f8046c6e6886dc3c17945238e63ee7c Mon Sep 17 00:00:00 2001
From: Michal Hocko 
Date: Wed, 29 Mar 2017 15:17:48 +0200
Subject: [PATCH] mm: remove return value from init_currently_empty_zone

init_currently_empty_zone doesn't have any error to return yet it is
still an int and callers try to be defensive and try to handle potential
error. Remove this nonsense and simplify all callers.

This patch shouldn't have any visible effect

Signed-off-by: Michal Hocko 
---
 include/linux/mmzone.h |  2 +-
 mm/memory_hotplug.c| 23 +--
 mm/page_alloc.c|  8 ++--
 3 files changed, 8 insertions(+), 25 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 3bac3ed71c7a..6973a3e6ad73 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -762,7 +762,7 @@ enum memmap_context {
MEMMAP_EARLY,
MEMMAP_HOTPLUG,
 };
-extern int init_currently_empty_zone(struct zone *zone, unsigned long 
start_pfn,
+extern void init_currently_empty_zone(struct zone *zone, unsigned long 
start_pfn,
 unsigned long size);
 
 extern void lruvec_init(struct lruvec *lruvec);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 699f5a2a8efd..1d55e5ec943f 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -343,27 +343,20 @@ static void fix_zone_id(struct zone *zone, unsigned long 
start_pfn,
set_page_links(pfn_to_page(pfn), zid, nid, pfn);
 }
 
-/* Can fail with -ENOMEM from allocating a wait table with vmalloc() or
- * alloc_bootmem_node_nopanic()/memblock_virt_alloc_node_nopanic() */
-static int __ref ensure_zone_is_initialized(struct zone *zone,
+static void __ref ensure_zone_is_initialized(struct zone *zone,
unsigned long start_pfn, unsigned long num_pages)
 {
if (zone_is_empty(zone))
-   return init_currently_empty_zone(zone, start_pfn, num_pages);
-
-   return 0;
+   init_currently_empty_zone(zone, start_pfn, num_pages);
 }
 
 static int __meminit move_pfn_range_left(struct zone *z1, struct zone *z2,
unsigned long start_pfn, unsigned long end_pfn)
 {
-   int ret;
unsigned long flags;
unsigned long z1_start_pfn;
 
-   ret = ensure_zone_is_initialized(z1, start_pfn, end_pfn - start_pfn);
-   if (ret)
-   return ret;
+   ensure_zone_is_initialized(z1, start_pfn, end_pfn - start_pfn);
 
pgdat_resize_lock(z1->zone_pgdat, );
 
@@ -399,13 +392,10 @@ static int __meminit move_pfn_range_left(struct zone *z1, 
struct zone *z2,
 static int __meminit move_pfn_range_right(struct zone *z1, struct zone *z2,
unsigned long start_pfn, unsigned long end_pfn)
 {
-   int ret;
unsigned long flags;
unsigned long z2_end_pfn;
 
-   ret = ensure_zone_is_initialized(z2, start_pfn, end_pfn - start_pfn);
-   if (ret)
-   return ret;
+   ensure_zone_is_initialized(z2, start_pfn, end_pfn - start_pfn);
 
pgdat_resize_lock(z1->zone_pgdat, );
 
@@ -476,12 +466,9 @@ static int __meminit __add_zone(struct zone *zone, 
unsigned long phys_start_pfn)
int nid = pgdat->node_id;
int zone_type;
unsigned long flags, pfn;
-   int ret;
 
zone_type = zone - pgdat->node_zones;
-   ret = ensure_zone_is_initialized(zone, phys_start_pfn, nr_pages);
-   if (ret)
-   return ret;
+   ensure_zone_is_initialized(zone, phys_start_pfn, nr_pages);
 
pgdat_resize_lock(zone->zone_pgdat, );
grow_zone_span(zone, phys_start_pfn, phys_start_pfn + nr_pages);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 756353d1e293..c6127f1a62e9 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5518,7 +5518,7 @@ static __meminit void zone_pcp_init(struct zone *zone)
 zone_batchsize(zone));
 }
 
-int __meminit init_currently_empty_zone(struct zone *zone,
+void __meminit init_currently_empty_zone(struct zone *zone,
unsigned long zone_start_pfn,
unsigned long size)
 {
@@ -5535,8 +5535,6 @@ int __meminit init_currently_empty_zone(struct zone *zone,
zone_start_pfn, (zone_start_pfn + size));
 
zone_init_free_lists(zone);
-
-   return 0;
 }
 
 #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
@@ -5999,7 +5997,6 @@ static void __paginginit free_area_init_core(struct 
pglist_data *pgdat)
 {
enum zone_type j;
int nid = pgdat->node_id;
-   int ret;
 
pgdat_resize_init(pgdat);
 #ifdef CONFIG_NUMA_BALANCING
@@ -6081,8 +6078,7 @@ static void __paginginit free_area_init_core(struct 
pglist_data *pgdat)
 
set_pageblock_order();
setup_usemap(pgdat, zone, zone_start_pfn, size);
-   ret = init_currently_empty_zone(zone, 

Re: [PATCH 3/6] mm: remove return value from init_currently_empty_zone

[Michal Hocko]

On Fri 31-03-17 15:06:41, Hillf Danton wrote:
> On March 31, 2017 2:49 PM Michal Hocko wrote: 
> > On Fri 31-03-17 11:49:49, Hillf Danton wrote:
> > [...]
> > > > -/* Can fail with -ENOMEM from allocating a wait table with vmalloc() or
> > > > - * alloc_bootmem_node_nopanic()/memblock_virt_alloc_node_nopanic() */
> > > > -static int __ref ensure_zone_is_initialized(struct zone *zone,
> > > > +static void __ref ensure_zone_is_initialized(struct zone *zone,
> > > > unsigned long start_pfn, unsigned long 
> > > > num_pages)
> > > >  {
> > > > -   if (zone_is_empty(zone))
> > > > -   return init_currently_empty_zone(zone, start_pfn, 
> > > > num_pages);
> > > > -
> > > > -   return 0;
> > > > +   if (!zone_is_empty(zone))
> > > > +   init_currently_empty_zone(zone, start_pfn, num_pages);
> > > >  }
> > > Semantic change added?
> > 
> > could you be more specific?
> 
> Well, I'm wondering why you are trying to initiate a nonempty zone.

Ups, another fuck up during the initial patch split up. Thanks for
catching that but it would be more helpful to be more specific during
the feedback. I am getting blind to the code I am staring for quite some
time so it was not obvious what you mean here.

Thanks
-- 
Michal Hocko
SUSE Labs

Re: [PATCH 3/6] mm: remove return value from init_currently_empty_zone

[Michal Hocko]

On Fri 31-03-17 15:06:41, Hillf Danton wrote:
> On March 31, 2017 2:49 PM Michal Hocko wrote: 
> > On Fri 31-03-17 11:49:49, Hillf Danton wrote:
> > [...]
> > > > -/* Can fail with -ENOMEM from allocating a wait table with vmalloc() or
> > > > - * alloc_bootmem_node_nopanic()/memblock_virt_alloc_node_nopanic() */
> > > > -static int __ref ensure_zone_is_initialized(struct zone *zone,
> > > > +static void __ref ensure_zone_is_initialized(struct zone *zone,
> > > > unsigned long start_pfn, unsigned long 
> > > > num_pages)
> > > >  {
> > > > -   if (zone_is_empty(zone))
> > > > -   return init_currently_empty_zone(zone, start_pfn, 
> > > > num_pages);
> > > > -
> > > > -   return 0;
> > > > +   if (!zone_is_empty(zone))
> > > > +   init_currently_empty_zone(zone, start_pfn, num_pages);
> > > >  }
> > > Semantic change added?
> > 
> > could you be more specific?
> 
> Well, I'm wondering why you are trying to initiate a nonempty zone.

Ups, another fuck up during the initial patch split up. Thanks for
catching that but it would be more helpful to be more specific during
the feedback. I am getting blind to the code I am staring for quite some
time so it was not obvious what you mean here.

Thanks
-- 
Michal Hocko
SUSE Labs

Re: [PATCH 3/6] mm: remove return value from init_currently_empty_zone

[Hillf Danton]

On March 31, 2017 2:49 PM Michal Hocko wrote: 
> On Fri 31-03-17 11:49:49, Hillf Danton wrote:
> [...]
> > > -/* Can fail with -ENOMEM from allocating a wait table with vmalloc() or
> > > - * alloc_bootmem_node_nopanic()/memblock_virt_alloc_node_nopanic() */
> > > -static int __ref ensure_zone_is_initialized(struct zone *zone,
> > > +static void __ref ensure_zone_is_initialized(struct zone *zone,
> > >   unsigned long start_pfn, unsigned long num_pages)
> > >  {
> > > - if (zone_is_empty(zone))
> > > - return init_currently_empty_zone(zone, start_pfn, num_pages);
> > > -
> > > - return 0;
> > > + if (!zone_is_empty(zone))
> > > + init_currently_empty_zone(zone, start_pfn, num_pages);
> > >  }
> > Semantic change added?
> 
> could you be more specific?

Well, I'm wondering why you are trying to initiate a nonempty zone.

Hillf

Re: [PATCH 3/6] mm: remove return value from init_currently_empty_zone

[Hillf Danton]

On March 31, 2017 2:49 PM Michal Hocko wrote: 
> On Fri 31-03-17 11:49:49, Hillf Danton wrote:
> [...]
> > > -/* Can fail with -ENOMEM from allocating a wait table with vmalloc() or
> > > - * alloc_bootmem_node_nopanic()/memblock_virt_alloc_node_nopanic() */
> > > -static int __ref ensure_zone_is_initialized(struct zone *zone,
> > > +static void __ref ensure_zone_is_initialized(struct zone *zone,
> > >   unsigned long start_pfn, unsigned long num_pages)
> > >  {
> > > - if (zone_is_empty(zone))
> > > - return init_currently_empty_zone(zone, start_pfn, num_pages);
> > > -
> > > - return 0;
> > > + if (!zone_is_empty(zone))
> > > + init_currently_empty_zone(zone, start_pfn, num_pages);
> > >  }
> > Semantic change added?
> 
> could you be more specific?

Well, I'm wondering why you are trying to initiate a nonempty zone.

Hillf

Re: [PATCH 3/6] mm: remove return value from init_currently_empty_zone

[Michal Hocko]

On Fri 31-03-17 11:49:49, Hillf Danton wrote:
[...]
> > -/* Can fail with -ENOMEM from allocating a wait table with vmalloc() or
> > - * alloc_bootmem_node_nopanic()/memblock_virt_alloc_node_nopanic() */
> > -static int __ref ensure_zone_is_initialized(struct zone *zone,
> > +static void __ref ensure_zone_is_initialized(struct zone *zone,
> > unsigned long start_pfn, unsigned long num_pages)
> >  {
> > -   if (zone_is_empty(zone))
> > -   return init_currently_empty_zone(zone, start_pfn, num_pages);
> > -
> > -   return 0;
> > +   if (!zone_is_empty(zone))
> > +   init_currently_empty_zone(zone, start_pfn, num_pages);
> >  }
> Semantic change added?

could you be more specific?
-- 
Michal Hocko
SUSE Labs

Re: [PATCH 3/6] mm: remove return value from init_currently_empty_zone

[Michal Hocko]

On Fri 31-03-17 11:49:49, Hillf Danton wrote:
[...]
> > -/* Can fail with -ENOMEM from allocating a wait table with vmalloc() or
> > - * alloc_bootmem_node_nopanic()/memblock_virt_alloc_node_nopanic() */
> > -static int __ref ensure_zone_is_initialized(struct zone *zone,
> > +static void __ref ensure_zone_is_initialized(struct zone *zone,
> > unsigned long start_pfn, unsigned long num_pages)
> >  {
> > -   if (zone_is_empty(zone))
> > -   return init_currently_empty_zone(zone, start_pfn, num_pages);
> > -
> > -   return 0;
> > +   if (!zone_is_empty(zone))
> > +   init_currently_empty_zone(zone, start_pfn, num_pages);
> >  }
> Semantic change added?

could you be more specific?
-- 
Michal Hocko
SUSE Labs

Re: [PATCH 3/6] mm: remove return value from init_currently_empty_zone

[Hillf Danton]

On March 30, 2017 7:55 PM Michal Hocko wrote: 
> 
> From: Michal Hocko 
> 
> init_currently_empty_zone doesn't have any error to return yet it is
> still an int and callers try to be defensive and try to handle potential
> error. Remove this nonsense and simplify all callers.
> 
It is already cut off in 1/6 in this series?



> -/* Can fail with -ENOMEM from allocating a wait table with vmalloc() or
> - * alloc_bootmem_node_nopanic()/memblock_virt_alloc_node_nopanic() */
> -static int __ref ensure_zone_is_initialized(struct zone *zone,
> +static void __ref ensure_zone_is_initialized(struct zone *zone,
>   unsigned long start_pfn, unsigned long num_pages)
>  {
> - if (zone_is_empty(zone))
> - return init_currently_empty_zone(zone, start_pfn, num_pages);
> -
> - return 0;
> + if (!zone_is_empty(zone))
> + init_currently_empty_zone(zone, start_pfn, num_pages);
>  }
Semantic change added?

Hillf

Re: [PATCH 3/6] mm: remove return value from init_currently_empty_zone

[Hillf Danton]

On March 30, 2017 7:55 PM Michal Hocko wrote: 
> 
> From: Michal Hocko 
> 
> init_currently_empty_zone doesn't have any error to return yet it is
> still an int and callers try to be defensive and try to handle potential
> error. Remove this nonsense and simplify all callers.
> 
It is already cut off in 1/6 in this series?



> -/* Can fail with -ENOMEM from allocating a wait table with vmalloc() or
> - * alloc_bootmem_node_nopanic()/memblock_virt_alloc_node_nopanic() */
> -static int __ref ensure_zone_is_initialized(struct zone *zone,
> +static void __ref ensure_zone_is_initialized(struct zone *zone,
>   unsigned long start_pfn, unsigned long num_pages)
>  {
> - if (zone_is_empty(zone))
> - return init_currently_empty_zone(zone, start_pfn, num_pages);
> -
> - return 0;
> + if (!zone_is_empty(zone))
> + init_currently_empty_zone(zone, start_pfn, num_pages);
>  }
Semantic change added?

Hillf

[PATCH 3/6] mm: remove return value from init_currently_empty_zone

[Michal Hocko]

From: Michal Hocko 

init_currently_empty_zone doesn't have any error to return yet it is
still an int and callers try to be defensive and try to handle potential
error. Remove this nonsense and simplify all callers.

This patch shouldn't have any visible effect

Signed-off-by: Michal Hocko 
---
 include/linux/mmzone.h |  2 +-
 mm/memory_hotplug.c| 25 ++---
 mm/page_alloc.c|  6 ++
 3 files changed, 9 insertions(+), 24 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index dbe3b32fe85d..c86c78617d17 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -768,7 +768,7 @@ enum memmap_context {
MEMMAP_EARLY,
MEMMAP_HOTPLUG,
 };
-extern int init_currently_empty_zone(struct zone *zone, unsigned long 
start_pfn,
+extern void init_currently_empty_zone(struct zone *zone, unsigned long 
start_pfn,
 unsigned long size);
 
 extern void lruvec_init(struct lruvec *lruvec);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 699f5a2a8efd..056dbbe6d20e 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -343,27 +343,20 @@ static void fix_zone_id(struct zone *zone, unsigned long 
start_pfn,
set_page_links(pfn_to_page(pfn), zid, nid, pfn);
 }
 
-/* Can fail with -ENOMEM from allocating a wait table with vmalloc() or
- * alloc_bootmem_node_nopanic()/memblock_virt_alloc_node_nopanic() */
-static int __ref ensure_zone_is_initialized(struct zone *zone,
+static void __ref ensure_zone_is_initialized(struct zone *zone,
unsigned long start_pfn, unsigned long num_pages)
 {
-   if (zone_is_empty(zone))
-   return init_currently_empty_zone(zone, start_pfn, num_pages);
-
-   return 0;
+   if (!zone_is_empty(zone))
+   init_currently_empty_zone(zone, start_pfn, num_pages);
 }
 
 static int __meminit move_pfn_range_left(struct zone *z1, struct zone *z2,
unsigned long start_pfn, unsigned long end_pfn)
 {
-   int ret;
unsigned long flags;
unsigned long z1_start_pfn;
 
-   ret = ensure_zone_is_initialized(z1, start_pfn, end_pfn - start_pfn);
-   if (ret)
-   return ret;
+   ensure_zone_is_initialized(z1, start_pfn, end_pfn - start_pfn);
 
pgdat_resize_lock(z1->zone_pgdat, );
 
@@ -399,13 +392,10 @@ static int __meminit move_pfn_range_left(struct zone *z1, 
struct zone *z2,
 static int __meminit move_pfn_range_right(struct zone *z1, struct zone *z2,
unsigned long start_pfn, unsigned long end_pfn)
 {
-   int ret;
unsigned long flags;
unsigned long z2_end_pfn;
 
-   ret = ensure_zone_is_initialized(z2, start_pfn, end_pfn - start_pfn);
-   if (ret)
-   return ret;
+   ensure_zone_is_initialized(z2, start_pfn, end_pfn - start_pfn);
 
pgdat_resize_lock(z1->zone_pgdat, );
 
@@ -476,12 +466,9 @@ static int __meminit __add_zone(struct zone *zone, 
unsigned long phys_start_pfn)
int nid = pgdat->node_id;
int zone_type;
unsigned long flags, pfn;
-   int ret;
 
zone_type = zone - pgdat->node_zones;
-   ret = ensure_zone_is_initialized(zone, phys_start_pfn, nr_pages);
-   if (ret)
-   return ret;
+   ensure_zone_is_initialized(zone, phys_start_pfn, nr_pages);
 
pgdat_resize_lock(zone->zone_pgdat, );
grow_zone_span(zone, phys_start_pfn, phys_start_pfn + nr_pages);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index af58b51c5897..c6127f1a62e9 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5518,7 +5518,7 @@ static __meminit void zone_pcp_init(struct zone *zone)
 zone_batchsize(zone));
 }
 
-int __meminit init_currently_empty_zone(struct zone *zone,
+void __meminit init_currently_empty_zone(struct zone *zone,
unsigned long zone_start_pfn,
unsigned long size)
 {
@@ -5997,7 +5997,6 @@ static void __paginginit free_area_init_core(struct 
pglist_data *pgdat)
 {
enum zone_type j;
int nid = pgdat->node_id;
-   int ret;
 
pgdat_resize_init(pgdat);
 #ifdef CONFIG_NUMA_BALANCING
@@ -6079,8 +6078,7 @@ static void __paginginit free_area_init_core(struct 
pglist_data *pgdat)
 
set_pageblock_order();
setup_usemap(pgdat, zone, zone_start_pfn, size);
-   ret = init_currently_empty_zone(zone, zone_start_pfn, size);
-   BUG_ON(ret);
+   init_currently_empty_zone(zone, zone_start_pfn, size);
memmap_init(size, nid, j, zone_start_pfn);
}
 }
-- 
2.11.0

[PATCH 3/6] mm: remove return value from init_currently_empty_zone

[Michal Hocko]

From: Michal Hocko 

init_currently_empty_zone doesn't have any error to return yet it is
still an int and callers try to be defensive and try to handle potential
error. Remove this nonsense and simplify all callers.

This patch shouldn't have any visible effect

Signed-off-by: Michal Hocko 
---
 include/linux/mmzone.h |  2 +-
 mm/memory_hotplug.c| 25 ++---
 mm/page_alloc.c|  6 ++
 3 files changed, 9 insertions(+), 24 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index dbe3b32fe85d..c86c78617d17 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -768,7 +768,7 @@ enum memmap_context {
MEMMAP_EARLY,
MEMMAP_HOTPLUG,
 };
-extern int init_currently_empty_zone(struct zone *zone, unsigned long 
start_pfn,
+extern void init_currently_empty_zone(struct zone *zone, unsigned long 
start_pfn,
 unsigned long size);
 
 extern void lruvec_init(struct lruvec *lruvec);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 699f5a2a8efd..056dbbe6d20e 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -343,27 +343,20 @@ static void fix_zone_id(struct zone *zone, unsigned long 
start_pfn,
set_page_links(pfn_to_page(pfn), zid, nid, pfn);
 }
 
-/* Can fail with -ENOMEM from allocating a wait table with vmalloc() or
- * alloc_bootmem_node_nopanic()/memblock_virt_alloc_node_nopanic() */
-static int __ref ensure_zone_is_initialized(struct zone *zone,
+static void __ref ensure_zone_is_initialized(struct zone *zone,
unsigned long start_pfn, unsigned long num_pages)
 {
-   if (zone_is_empty(zone))
-   return init_currently_empty_zone(zone, start_pfn, num_pages);
-
-   return 0;
+   if (!zone_is_empty(zone))
+   init_currently_empty_zone(zone, start_pfn, num_pages);
 }
 
 static int __meminit move_pfn_range_left(struct zone *z1, struct zone *z2,
unsigned long start_pfn, unsigned long end_pfn)
 {
-   int ret;
unsigned long flags;
unsigned long z1_start_pfn;
 
-   ret = ensure_zone_is_initialized(z1, start_pfn, end_pfn - start_pfn);
-   if (ret)
-   return ret;
+   ensure_zone_is_initialized(z1, start_pfn, end_pfn - start_pfn);
 
pgdat_resize_lock(z1->zone_pgdat, );
 
@@ -399,13 +392,10 @@ static int __meminit move_pfn_range_left(struct zone *z1, 
struct zone *z2,
 static int __meminit move_pfn_range_right(struct zone *z1, struct zone *z2,
unsigned long start_pfn, unsigned long end_pfn)
 {
-   int ret;
unsigned long flags;
unsigned long z2_end_pfn;
 
-   ret = ensure_zone_is_initialized(z2, start_pfn, end_pfn - start_pfn);
-   if (ret)
-   return ret;
+   ensure_zone_is_initialized(z2, start_pfn, end_pfn - start_pfn);
 
pgdat_resize_lock(z1->zone_pgdat, );
 
@@ -476,12 +466,9 @@ static int __meminit __add_zone(struct zone *zone, 
unsigned long phys_start_pfn)
int nid = pgdat->node_id;
int zone_type;
unsigned long flags, pfn;
-   int ret;
 
zone_type = zone - pgdat->node_zones;
-   ret = ensure_zone_is_initialized(zone, phys_start_pfn, nr_pages);
-   if (ret)
-   return ret;
+   ensure_zone_is_initialized(zone, phys_start_pfn, nr_pages);
 
pgdat_resize_lock(zone->zone_pgdat, );
grow_zone_span(zone, phys_start_pfn, phys_start_pfn + nr_pages);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index af58b51c5897..c6127f1a62e9 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5518,7 +5518,7 @@ static __meminit void zone_pcp_init(struct zone *zone)
 zone_batchsize(zone));
 }
 
-int __meminit init_currently_empty_zone(struct zone *zone,
+void __meminit init_currently_empty_zone(struct zone *zone,
unsigned long zone_start_pfn,
unsigned long size)
 {
@@ -5997,7 +5997,6 @@ static void __paginginit free_area_init_core(struct 
pglist_data *pgdat)
 {
enum zone_type j;
int nid = pgdat->node_id;
-   int ret;
 
pgdat_resize_init(pgdat);
 #ifdef CONFIG_NUMA_BALANCING
@@ -6079,8 +6078,7 @@ static void __paginginit free_area_init_core(struct 
pglist_data *pgdat)
 
set_pageblock_order();
setup_usemap(pgdat, zone, zone_start_pfn, size);
-   ret = init_currently_empty_zone(zone, zone_start_pfn, size);
-   BUG_ON(ret);
+   init_currently_empty_zone(zone, zone_start_pfn, size);
memmap_init(size, nid, j, zone_start_pfn);
}
 }
-- 
2.11.0