Re: [PATCH 2/3] staging: lowmemorykiller: count anon pages only when we have swap devices

[Ganesh Mahendran]

2016-06-23 16:42 GMT+08:00 Sergey Senozhatsky
:
> On (06/22/16 11:27), Ganesh Mahendran wrote:
> [..]
>> > > Signed-off-by: Ganesh Mahendran 
>> > > ---
>> > >  drivers/staging/android/lowmemorykiller.c | 12 
>> > >  1 file changed, 8 insertions(+), 4 deletions(-)
>> > >
>> > > diff --git a/drivers/staging/android/lowmemorykiller.c 
>> > > b/drivers/staging/android/lowmemorykiller.c
>> > > index 6da9260..1d8de47 100644
>> > > --- a/drivers/staging/android/lowmemorykiller.c
>> > > +++ b/drivers/staging/android/lowmemorykiller.c
>> > > @@ -73,10 +73,14 @@ static unsigned long lowmem_deathpending_timeout;
>> > >  static unsigned long lowmem_count(struct shrinker *s,
>> > > struct shrink_control *sc)
>> > >  {
>> > > - return global_page_state(NR_ACTIVE_ANON) +
>> > > - global_page_state(NR_ACTIVE_FILE) +
>> > > - global_page_state(NR_INACTIVE_ANON) +
>> > > - global_page_state(NR_INACTIVE_FILE);
>> > > + unsigned long freeable = global_page_state(NR_ACTIVE_FILE) +
>> > > + global_page_state(NR_INACTIVE_FILE);
>> > > +
>> > > + if (get_nr_swap_pages() > 0)
>> > > + freeable += global_page_state(NR_ACTIVE_ANON) +
>> > > + global_page_state(NR_INACTIVE_ANON);
>> > > +
>> > > + return freeable;
>> > >  }
>> > >
>> > >  static unsigned long lowmem_scan(struct shrinker *s, struct 
>> > > shrink_control *sc)
>> >
>> > Shouldn't this be advertising the amount of memory that is freeable by
>> > killing the process with the highest priority oom_score_adj?  It's not
>> > legitimate to say it can free all anon and file memory if nothing is oom
>> > killable, so this function is wrong both originally and with your patched
>> > version.
>>
>> Yes, so should we just simply return 1 to make do_shrink_slab() go ahead?
>> Then lowmem_scan() will do the real job to scan all the process.
>
> hm, looking at ->scan (lowmem_scan) shouldn't it return SHRINK_STOP
> when it has nothing to free instead of 0?

Yes, you are right. It should return SHRINK_STOP.

>
> -ss

Re: [PATCH 2/3] staging: lowmemorykiller: count anon pages only when we have swap devices

[Ganesh Mahendran]

2016-06-23 16:42 GMT+08:00 Sergey Senozhatsky
:
> On (06/22/16 11:27), Ganesh Mahendran wrote:
> [..]
>> > > Signed-off-by: Ganesh Mahendran 
>> > > ---
>> > >  drivers/staging/android/lowmemorykiller.c | 12 
>> > >  1 file changed, 8 insertions(+), 4 deletions(-)
>> > >
>> > > diff --git a/drivers/staging/android/lowmemorykiller.c 
>> > > b/drivers/staging/android/lowmemorykiller.c
>> > > index 6da9260..1d8de47 100644
>> > > --- a/drivers/staging/android/lowmemorykiller.c
>> > > +++ b/drivers/staging/android/lowmemorykiller.c
>> > > @@ -73,10 +73,14 @@ static unsigned long lowmem_deathpending_timeout;
>> > >  static unsigned long lowmem_count(struct shrinker *s,
>> > > struct shrink_control *sc)
>> > >  {
>> > > - return global_page_state(NR_ACTIVE_ANON) +
>> > > - global_page_state(NR_ACTIVE_FILE) +
>> > > - global_page_state(NR_INACTIVE_ANON) +
>> > > - global_page_state(NR_INACTIVE_FILE);
>> > > + unsigned long freeable = global_page_state(NR_ACTIVE_FILE) +
>> > > + global_page_state(NR_INACTIVE_FILE);
>> > > +
>> > > + if (get_nr_swap_pages() > 0)
>> > > + freeable += global_page_state(NR_ACTIVE_ANON) +
>> > > + global_page_state(NR_INACTIVE_ANON);
>> > > +
>> > > + return freeable;
>> > >  }
>> > >
>> > >  static unsigned long lowmem_scan(struct shrinker *s, struct 
>> > > shrink_control *sc)
>> >
>> > Shouldn't this be advertising the amount of memory that is freeable by
>> > killing the process with the highest priority oom_score_adj?  It's not
>> > legitimate to say it can free all anon and file memory if nothing is oom
>> > killable, so this function is wrong both originally and with your patched
>> > version.
>>
>> Yes, so should we just simply return 1 to make do_shrink_slab() go ahead?
>> Then lowmem_scan() will do the real job to scan all the process.
>
> hm, looking at ->scan (lowmem_scan) shouldn't it return SHRINK_STOP
> when it has nothing to free instead of 0?

Yes, you are right. It should return SHRINK_STOP.

>
> -ss

Re: [PATCH 2/3] staging: lowmemorykiller: count anon pages only when we have swap devices

[Sergey Senozhatsky]

On (06/22/16 11:27), Ganesh Mahendran wrote:
[..]
> > > Signed-off-by: Ganesh Mahendran 
> > > ---
> > >  drivers/staging/android/lowmemorykiller.c | 12 
> > >  1 file changed, 8 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/drivers/staging/android/lowmemorykiller.c 
> > > b/drivers/staging/android/lowmemorykiller.c
> > > index 6da9260..1d8de47 100644
> > > --- a/drivers/staging/android/lowmemorykiller.c
> > > +++ b/drivers/staging/android/lowmemorykiller.c
> > > @@ -73,10 +73,14 @@ static unsigned long lowmem_deathpending_timeout;
> > >  static unsigned long lowmem_count(struct shrinker *s,
> > > struct shrink_control *sc)
> > >  {
> > > - return global_page_state(NR_ACTIVE_ANON) +
> > > - global_page_state(NR_ACTIVE_FILE) +
> > > - global_page_state(NR_INACTIVE_ANON) +
> > > - global_page_state(NR_INACTIVE_FILE);
> > > + unsigned long freeable = global_page_state(NR_ACTIVE_FILE) +
> > > + global_page_state(NR_INACTIVE_FILE);
> > > +
> > > + if (get_nr_swap_pages() > 0)
> > > + freeable += global_page_state(NR_ACTIVE_ANON) +
> > > + global_page_state(NR_INACTIVE_ANON);
> > > +
> > > + return freeable;
> > >  }
> > >  
> > >  static unsigned long lowmem_scan(struct shrinker *s, struct 
> > > shrink_control *sc)
> > 
> > Shouldn't this be advertising the amount of memory that is freeable by 
> > killing the process with the highest priority oom_score_adj?  It's not 
> > legitimate to say it can free all anon and file memory if nothing is oom 
> > killable, so this function is wrong both originally and with your patched 
> > version.
> 
> Yes, so should we just simply return 1 to make do_shrink_slab() go ahead?
> Then lowmem_scan() will do the real job to scan all the process.

hm, looking at ->scan (lowmem_scan) shouldn't it return SHRINK_STOP
when it has nothing to free instead of 0?

-ss

Re: [PATCH 2/3] staging: lowmemorykiller: count anon pages only when we have swap devices

[Sergey Senozhatsky]

On (06/22/16 11:27), Ganesh Mahendran wrote:
[..]
> > > Signed-off-by: Ganesh Mahendran 
> > > ---
> > >  drivers/staging/android/lowmemorykiller.c | 12 
> > >  1 file changed, 8 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/drivers/staging/android/lowmemorykiller.c 
> > > b/drivers/staging/android/lowmemorykiller.c
> > > index 6da9260..1d8de47 100644
> > > --- a/drivers/staging/android/lowmemorykiller.c
> > > +++ b/drivers/staging/android/lowmemorykiller.c
> > > @@ -73,10 +73,14 @@ static unsigned long lowmem_deathpending_timeout;
> > >  static unsigned long lowmem_count(struct shrinker *s,
> > > struct shrink_control *sc)
> > >  {
> > > - return global_page_state(NR_ACTIVE_ANON) +
> > > - global_page_state(NR_ACTIVE_FILE) +
> > > - global_page_state(NR_INACTIVE_ANON) +
> > > - global_page_state(NR_INACTIVE_FILE);
> > > + unsigned long freeable = global_page_state(NR_ACTIVE_FILE) +
> > > + global_page_state(NR_INACTIVE_FILE);
> > > +
> > > + if (get_nr_swap_pages() > 0)
> > > + freeable += global_page_state(NR_ACTIVE_ANON) +
> > > + global_page_state(NR_INACTIVE_ANON);
> > > +
> > > + return freeable;
> > >  }
> > >  
> > >  static unsigned long lowmem_scan(struct shrinker *s, struct 
> > > shrink_control *sc)
> > 
> > Shouldn't this be advertising the amount of memory that is freeable by 
> > killing the process with the highest priority oom_score_adj?  It's not 
> > legitimate to say it can free all anon and file memory if nothing is oom 
> > killable, so this function is wrong both originally and with your patched 
> > version.
> 
> Yes, so should we just simply return 1 to make do_shrink_slab() go ahead?
> Then lowmem_scan() will do the real job to scan all the process.

hm, looking at ->scan (lowmem_scan) shouldn't it return SHRINK_STOP
when it has nothing to free instead of 0?

-ss

Re: [PATCH 2/3] staging: lowmemorykiller: count anon pages only when we have swap devices

[Ganesh Mahendran]

Hi, David:

On Tue, Jun 21, 2016 at 01:22:00PM -0700, David Rientjes wrote:
> On Tue, 21 Jun 2016, Ganesh Mahendran wrote:
> 
> > lowmem_count() should only count anon pages when we have swap device.
> > 
> 
> Why?

I make a mistake. I thought lowmem_count will return the shrinkalbe page
of a process.

> 
> > Signed-off-by: Ganesh Mahendran 
> > ---
> >  drivers/staging/android/lowmemorykiller.c | 12 
> >  1 file changed, 8 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/staging/android/lowmemorykiller.c 
> > b/drivers/staging/android/lowmemorykiller.c
> > index 6da9260..1d8de47 100644
> > --- a/drivers/staging/android/lowmemorykiller.c
> > +++ b/drivers/staging/android/lowmemorykiller.c
> > @@ -73,10 +73,14 @@ static unsigned long lowmem_deathpending_timeout;
> >  static unsigned long lowmem_count(struct shrinker *s,
> >   struct shrink_control *sc)
> >  {
> > -   return global_page_state(NR_ACTIVE_ANON) +
> > -   global_page_state(NR_ACTIVE_FILE) +
> > -   global_page_state(NR_INACTIVE_ANON) +
> > -   global_page_state(NR_INACTIVE_FILE);
> > +   unsigned long freeable = global_page_state(NR_ACTIVE_FILE) +
> > +   global_page_state(NR_INACTIVE_FILE);
> > +
> > +   if (get_nr_swap_pages() > 0)
> > +   freeable += global_page_state(NR_ACTIVE_ANON) +
> > +   global_page_state(NR_INACTIVE_ANON);
> > +
> > +   return freeable;
> >  }
> >  
> >  static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control 
> > *sc)
> 
> Shouldn't this be advertising the amount of memory that is freeable by 
> killing the process with the highest priority oom_score_adj?  It's not 
> legitimate to say it can free all anon and file memory if nothing is oom 
> killable, so this function is wrong both originally and with your patched 
> version.

Yes, so should we just simply return 1 to make do_shrink_slab() go ahead?
Then lowmem_scan() will do the real job to scan all the process.

Thanks.

Re: [PATCH 2/3] staging: lowmemorykiller: count anon pages only when we have swap devices

[Ganesh Mahendran]

Hi, David:

On Tue, Jun 21, 2016 at 01:22:00PM -0700, David Rientjes wrote:
> On Tue, 21 Jun 2016, Ganesh Mahendran wrote:
> 
> > lowmem_count() should only count anon pages when we have swap device.
> > 
> 
> Why?

I make a mistake. I thought lowmem_count will return the shrinkalbe page
of a process.

> 
> > Signed-off-by: Ganesh Mahendran 
> > ---
> >  drivers/staging/android/lowmemorykiller.c | 12 
> >  1 file changed, 8 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/staging/android/lowmemorykiller.c 
> > b/drivers/staging/android/lowmemorykiller.c
> > index 6da9260..1d8de47 100644
> > --- a/drivers/staging/android/lowmemorykiller.c
> > +++ b/drivers/staging/android/lowmemorykiller.c
> > @@ -73,10 +73,14 @@ static unsigned long lowmem_deathpending_timeout;
> >  static unsigned long lowmem_count(struct shrinker *s,
> >   struct shrink_control *sc)
> >  {
> > -   return global_page_state(NR_ACTIVE_ANON) +
> > -   global_page_state(NR_ACTIVE_FILE) +
> > -   global_page_state(NR_INACTIVE_ANON) +
> > -   global_page_state(NR_INACTIVE_FILE);
> > +   unsigned long freeable = global_page_state(NR_ACTIVE_FILE) +
> > +   global_page_state(NR_INACTIVE_FILE);
> > +
> > +   if (get_nr_swap_pages() > 0)
> > +   freeable += global_page_state(NR_ACTIVE_ANON) +
> > +   global_page_state(NR_INACTIVE_ANON);
> > +
> > +   return freeable;
> >  }
> >  
> >  static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control 
> > *sc)
> 
> Shouldn't this be advertising the amount of memory that is freeable by 
> killing the process with the highest priority oom_score_adj?  It's not 
> legitimate to say it can free all anon and file memory if nothing is oom 
> killable, so this function is wrong both originally and with your patched 
> version.

Yes, so should we just simply return 1 to make do_shrink_slab() go ahead?
Then lowmem_scan() will do the real job to scan all the process.

Thanks.

Re: [PATCH 2/3] staging: lowmemorykiller: count anon pages only when we have swap devices

[David Rientjes]

On Tue, 21 Jun 2016, Ganesh Mahendran wrote:

> lowmem_count() should only count anon pages when we have swap device.
> 

Why?

> Signed-off-by: Ganesh Mahendran 
> ---
>  drivers/staging/android/lowmemorykiller.c | 12 
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/staging/android/lowmemorykiller.c 
> b/drivers/staging/android/lowmemorykiller.c
> index 6da9260..1d8de47 100644
> --- a/drivers/staging/android/lowmemorykiller.c
> +++ b/drivers/staging/android/lowmemorykiller.c
> @@ -73,10 +73,14 @@ static unsigned long lowmem_deathpending_timeout;
>  static unsigned long lowmem_count(struct shrinker *s,
> struct shrink_control *sc)
>  {
> - return global_page_state(NR_ACTIVE_ANON) +
> - global_page_state(NR_ACTIVE_FILE) +
> - global_page_state(NR_INACTIVE_ANON) +
> - global_page_state(NR_INACTIVE_FILE);
> + unsigned long freeable = global_page_state(NR_ACTIVE_FILE) +
> + global_page_state(NR_INACTIVE_FILE);
> +
> + if (get_nr_swap_pages() > 0)
> + freeable += global_page_state(NR_ACTIVE_ANON) +
> + global_page_state(NR_INACTIVE_ANON);
> +
> + return freeable;
>  }
>  
>  static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control 
> *sc)

Shouldn't this be advertising the amount of memory that is freeable by 
killing the process with the highest priority oom_score_adj?  It's not 
legitimate to say it can free all anon and file memory if nothing is oom 
killable, so this function is wrong both originally and with your patched 
version.

Re: [PATCH 2/3] staging: lowmemorykiller: count anon pages only when we have swap devices

[David Rientjes]

On Tue, 21 Jun 2016, Ganesh Mahendran wrote:

> lowmem_count() should only count anon pages when we have swap device.
> 

Why?

> Signed-off-by: Ganesh Mahendran 
> ---
>  drivers/staging/android/lowmemorykiller.c | 12 
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/staging/android/lowmemorykiller.c 
> b/drivers/staging/android/lowmemorykiller.c
> index 6da9260..1d8de47 100644
> --- a/drivers/staging/android/lowmemorykiller.c
> +++ b/drivers/staging/android/lowmemorykiller.c
> @@ -73,10 +73,14 @@ static unsigned long lowmem_deathpending_timeout;
>  static unsigned long lowmem_count(struct shrinker *s,
> struct shrink_control *sc)
>  {
> - return global_page_state(NR_ACTIVE_ANON) +
> - global_page_state(NR_ACTIVE_FILE) +
> - global_page_state(NR_INACTIVE_ANON) +
> - global_page_state(NR_INACTIVE_FILE);
> + unsigned long freeable = global_page_state(NR_ACTIVE_FILE) +
> + global_page_state(NR_INACTIVE_FILE);
> +
> + if (get_nr_swap_pages() > 0)
> + freeable += global_page_state(NR_ACTIVE_ANON) +
> + global_page_state(NR_INACTIVE_ANON);
> +
> + return freeable;
>  }
>  
>  static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control 
> *sc)

Shouldn't this be advertising the amount of memory that is freeable by 
killing the process with the highest priority oom_score_adj?  It's not 
legitimate to say it can free all anon and file memory if nothing is oom 
killable, so this function is wrong both originally and with your patched 
version.

[PATCH 2/3] staging: lowmemorykiller: count anon pages only when we have swap devices

[Ganesh Mahendran]

lowmem_count() should only count anon pages when we have swap device.

Signed-off-by: Ganesh Mahendran 
---
 drivers/staging/android/lowmemorykiller.c | 12 
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/android/lowmemorykiller.c 
b/drivers/staging/android/lowmemorykiller.c
index 6da9260..1d8de47 100644
--- a/drivers/staging/android/lowmemorykiller.c
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -73,10 +73,14 @@ static unsigned long lowmem_deathpending_timeout;
 static unsigned long lowmem_count(struct shrinker *s,
  struct shrink_control *sc)
 {
-   return global_page_state(NR_ACTIVE_ANON) +
-   global_page_state(NR_ACTIVE_FILE) +
-   global_page_state(NR_INACTIVE_ANON) +
-   global_page_state(NR_INACTIVE_FILE);
+   unsigned long freeable = global_page_state(NR_ACTIVE_FILE) +
+   global_page_state(NR_INACTIVE_FILE);
+
+   if (get_nr_swap_pages() > 0)
+   freeable += global_page_state(NR_ACTIVE_ANON) +
+   global_page_state(NR_INACTIVE_ANON);
+
+   return freeable;
 }
 
 static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
-- 
1.9.1

[PATCH 2/3] staging: lowmemorykiller: count anon pages only when we have swap devices

[Ganesh Mahendran]

lowmem_count() should only count anon pages when we have swap device.

Signed-off-by: Ganesh Mahendran 
---
 drivers/staging/android/lowmemorykiller.c | 12 
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/android/lowmemorykiller.c 
b/drivers/staging/android/lowmemorykiller.c
index 6da9260..1d8de47 100644
--- a/drivers/staging/android/lowmemorykiller.c
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -73,10 +73,14 @@ static unsigned long lowmem_deathpending_timeout;
 static unsigned long lowmem_count(struct shrinker *s,
  struct shrink_control *sc)
 {
-   return global_page_state(NR_ACTIVE_ANON) +
-   global_page_state(NR_ACTIVE_FILE) +
-   global_page_state(NR_INACTIVE_ANON) +
-   global_page_state(NR_INACTIVE_FILE);
+   unsigned long freeable = global_page_state(NR_ACTIVE_FILE) +
+   global_page_state(NR_INACTIVE_FILE);
+
+   if (get_nr_swap_pages() > 0)
+   freeable += global_page_state(NR_ACTIVE_ANON) +
+   global_page_state(NR_INACTIVE_ANON);
+
+   return freeable;
 }
 
 static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
-- 
1.9.1