34-rc1-git3 build failure with CGROUP_MEM_RES_CTLR_SWAP=y

34-rc1-git3 build failure with CGROUP_MEM_RES_CTLR_SWAP=y

[Sachin Sant]

On a PowerPC box, latest 34-rc1 git(d89b218b8...) fails to build
with CGROUPS_MEM_RES_CTRL_SWAP=y. 

LD      init/built-in.o
LD      .tmp_vmlinux1
mm/built-in.o: In function __xchg:
arch/powerpc/include/asm/system.h:331: undefined reference to .__xchg_called_with_bad_pointer
mm/built-in.o: In function __cmpxchg:
arch/powerpc/include/asm/system.h:474: undefined reference to .__cmpxchg_called_with_bad_pointer
make: *** [.tmp_vmlinux1] Error 1

The code in question was added via commit 024914477e...

memcg: move charges of anonymous swap

Thanks
-Sachin


-- 

---------------------------------
Sachin Sant
IBM Linux Technology Center
India Systems and Technology Labs
Bangalore, India
---------------------------------

[BUGFIX][PATCH] memcg: avoid use cmpxchg in swap cgroup maintainance (Was Re: 34-rc1-git3 build failure with CGROUP_MEM_RES_CTLR_SWAP=y

[KAMEZAWA Hiroyuki]

On Sun, 14 Mar 2010 16:18:06 +0530
Sachin Sant <sachinp@in.ibm.com> wrote:

> On a PowerPC box, latest 34-rc1 git(d89b218b8...) fails to build
> with CGROUPS_MEM_RES_CTRL_SWAP=y. 
> 
> LD      init/built-in.o
> LD      .tmp_vmlinux1
> mm/built-in.o: In function __xchg:
> arch/powerpc/include/asm/system.h:331: undefined reference to .__xchg_called_with_bad_pointer
> mm/built-in.o: In function __cmpxchg:
> arch/powerpc/include/asm/system.h:474: undefined reference to .__cmpxchg_called_with_bad_pointer
> make: *** [.tmp_vmlinux1] Error 1
> 
> The code in question was added via commit 024914477e...
> 
> memcg: move charges of anonymous swap
> 
Oh..ok, powerpc (and other archs?) can't do 2byte cmpxchg and xchg.
Then, we should use spinlock rather than that.

How about this ? Nishimura-san, could you consider something better ?
We need a quick fix.

==
swap_cgroup uses 2bytes data and uses cmpxchg in a new operation.
2byte cmpxchg/xchg is not available on some archs. This patch replaces
cmpxchg/xchg with operations under lock.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
 mm/page_cgroup.c |   20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

Index: mmotm-2.6.34-Mar11/mm/page_cgroup.c
===================================================================
--- mmotm-2.6.34-Mar11.orig/mm/page_cgroup.c
+++ mmotm-2.6.34-Mar11/mm/page_cgroup.c
@@ -284,6 +284,7 @@ static DEFINE_MUTEX(swap_cgroup_mutex);
 struct swap_cgroup_ctrl {
 	struct page **map;
 	unsigned long length;
+	spinlock_t	lock;
 };
 
 struct swap_cgroup_ctrl swap_cgroup_ctrl[MAX_SWAPFILES];
@@ -353,16 +354,22 @@ unsigned short swap_cgroup_cmpxchg(swp_e
 	struct swap_cgroup_ctrl *ctrl;
 	struct page *mappage;
 	struct swap_cgroup *sc;
+	unsigned long flags;
+	unsigned short retval;
 
 	ctrl = &swap_cgroup_ctrl[type];
 
 	mappage = ctrl->map[idx];
 	sc = page_address(mappage);
 	sc += pos;
-	if (cmpxchg(&sc->id, old, new) == old)
-		return old;
+	spin_lock_irqsave(&ctrl->lock, flags);
+	retval = sc->id;
+	if (retval == old)
+		sc->id = new;
 	else
-		return 0;
+		retval = 0;
+	spin_unlock_irqrestore(&ctrl->lock, flags);
+	return retval;
 }
 
 /**
@@ -383,13 +390,17 @@ unsigned short swap_cgroup_record(swp_en
 	struct page *mappage;
 	struct swap_cgroup *sc;
 	unsigned short old;
+	unsigned long flags;
 
 	ctrl = &swap_cgroup_ctrl[type];
 
 	mappage = ctrl->map[idx];
 	sc = page_address(mappage);
 	sc += pos;
-	old = xchg(&sc->id, id);
+	spin_lock_irqsave(&ctrl->lock, flags);
+	old = sc->id;
+	sc->id = id;
+	spin_unlock_irqrestore(&ctrl->lock, flags);
 
 	return old;
 }
@@ -441,6 +452,7 @@ int swap_cgroup_swapon(int type, unsigne
 	mutex_lock(&swap_cgroup_mutex);
 	ctrl->length = length;
 	ctrl->map = array;
+	spin_lock_init(&ctrl->lock);
 	if (swap_cgroup_prepare(type)) {
 		/* memory shortage */
 		ctrl->map = NULL;

Re: 34-rc1-git3 build failure with CGROUP_MEM_RES_CTLR_SWAP=y

[Michael Ellerman]

[-- Attachment #1: Type: text/plain, Size: 1055 bytes --]

On Sun, 2010-03-14 at 16:18 +0530, Sachin Sant wrote:
> On a PowerPC box, latest 34-rc1 git(d89b218b8...) fails to build
> with CGROUPS_MEM_RES_CTRL_SWAP=y. 
> 
> LD      init/built-in.o
> LD      .tmp_vmlinux1
> mm/built-in.o: In function __xchg:
> arch/powerpc/include/asm/system.h:331: undefined reference to .__xchg_called_with_bad_pointer
> mm/built-in.o: In function __cmpxchg:
> arch/powerpc/include/asm/system.h:474: undefined reference to .__cmpxchg_called_with_bad_pointer
> make: *** [.tmp_vmlinux1] Error 1
> 
> The code in question was added via commit 024914477e...
> 
> memcg: move charges of anonymous swap

struct swap_cgroup
{                                                        
	unsigned short          id;
};

+unsigned short swap_cgroup_cmpxchg(swp_entry_t ent,
+                                       unsigned short old, unsigned short new)
+{
...
+       struct swap_cgroup *sc;
...
+       if (cmpxchg(&sc->id, old, new) == old)


On powerpc cmpxchg() currently only handles u32 & u64.

cheers

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Re: [BUGFIX][PATCH] memcg: avoid use cmpxchg in swap cgroup maintainance (Was Re: 34-rc1-git3 build failure with CGROUP_MEM_RES_CTLR_SWAP=y

[Balbir Singh]

* KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> [2010-03-15 10:02:02]:

> On Sun, 14 Mar 2010 16:18:06 +0530
> Sachin Sant <sachinp@in.ibm.com> wrote:
> 
> > On a PowerPC box, latest 34-rc1 git(d89b218b8...) fails to build
> > with CGROUPS_MEM_RES_CTRL_SWAP=y. 
> > 
> > LD      init/built-in.o
> > LD      .tmp_vmlinux1
> > mm/built-in.o: In function __xchg:
> > arch/powerpc/include/asm/system.h:331: undefined reference to .__xchg_called_with_bad_pointer
> > mm/built-in.o: In function __cmpxchg:
> > arch/powerpc/include/asm/system.h:474: undefined reference to .__cmpxchg_called_with_bad_pointer
> > make: *** [.tmp_vmlinux1] Error 1
> > 
> > The code in question was added via commit 024914477e...
> > 
> > memcg: move charges of anonymous swap
> > 
> Oh..ok, powerpc (and other archs?) can't do 2byte cmpxchg and xchg.
> Then, we should use spinlock rather than that.
> 
> How about this ? Nishimura-san, could you consider something better ?
> We need a quick fix.
>

Looks good to me

 
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
 

-- 
	Three Cheers,
	Balbir

Re: [BUGFIX][PATCH] memcg: avoid use cmpxchg in swap cgroup maintainance (Was Re: 34-rc1-git3 build failure with CGROUP_MEM_RES_CTLR_SWAP=y

[Daisuke Nishimura]

On Mon, 15 Mar 2010 10:02:02 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> On Sun, 14 Mar 2010 16:18:06 +0530
> Sachin Sant <sachinp@in.ibm.com> wrote:
> 
> > On a PowerPC box, latest 34-rc1 git(d89b218b8...) fails to build
> > with CGROUPS_MEM_RES_CTRL_SWAP=y. 
> > 
> > LD      init/built-in.o
> > LD      .tmp_vmlinux1
> > mm/built-in.o: In function __xchg:
> > arch/powerpc/include/asm/system.h:331: undefined reference to .__xchg_called_with_bad_pointer
> > mm/built-in.o: In function __cmpxchg:
> > arch/powerpc/include/asm/system.h:474: undefined reference to .__cmpxchg_called_with_bad_pointer
> > make: *** [.tmp_vmlinux1] Error 1
> > 
> > The code in question was added via commit 024914477e...
> > 
> > memcg: move charges of anonymous swap
> > 
> Oh..ok, powerpc (and other archs?) can't do 2byte cmpxchg and xchg.
> Then, we should use spinlock rather than that.
> 
> How about this ? Nishimura-san, could you consider something better ?
> We need a quick fix.
> 
Thank you for fixing this issue.
I think it increases the size of swap_cgroup_ctrl a bit,
but I think it's a good fix.

> ==
> swap_cgroup uses 2bytes data and uses cmpxchg in a new operation.
> 2byte cmpxchg/xchg is not available on some archs. This patch replaces
> cmpxchg/xchg with operations under lock.
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>

Thanks,
Daisuke Nishimura.
> ---
>  mm/page_cgroup.c |   20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
> 
> Index: mmotm-2.6.34-Mar11/mm/page_cgroup.c
> ===================================================================
> --- mmotm-2.6.34-Mar11.orig/mm/page_cgroup.c
> +++ mmotm-2.6.34-Mar11/mm/page_cgroup.c
> @@ -284,6 +284,7 @@ static DEFINE_MUTEX(swap_cgroup_mutex);
>  struct swap_cgroup_ctrl {
>  	struct page **map;
>  	unsigned long length;
> +	spinlock_t	lock;
>  };
>  
>  struct swap_cgroup_ctrl swap_cgroup_ctrl[MAX_SWAPFILES];
> @@ -353,16 +354,22 @@ unsigned short swap_cgroup_cmpxchg(swp_e
>  	struct swap_cgroup_ctrl *ctrl;
>  	struct page *mappage;
>  	struct swap_cgroup *sc;
> +	unsigned long flags;
> +	unsigned short retval;
>  
>  	ctrl = &swap_cgroup_ctrl[type];
>  
>  	mappage = ctrl->map[idx];
>  	sc = page_address(mappage);
>  	sc += pos;
> -	if (cmpxchg(&sc->id, old, new) == old)
> -		return old;
> +	spin_lock_irqsave(&ctrl->lock, flags);
> +	retval = sc->id;
> +	if (retval == old)
> +		sc->id = new;
>  	else
> -		return 0;
> +		retval = 0;
> +	spin_unlock_irqrestore(&ctrl->lock, flags);
> +	return retval;
>  }
>  
>  /**
> @@ -383,13 +390,17 @@ unsigned short swap_cgroup_record(swp_en
>  	struct page *mappage;
>  	struct swap_cgroup *sc;
>  	unsigned short old;
> +	unsigned long flags;
>  
>  	ctrl = &swap_cgroup_ctrl[type];
>  
>  	mappage = ctrl->map[idx];
>  	sc = page_address(mappage);
>  	sc += pos;
> -	old = xchg(&sc->id, id);
> +	spin_lock_irqsave(&ctrl->lock, flags);
> +	old = sc->id;
> +	sc->id = id;
> +	spin_unlock_irqrestore(&ctrl->lock, flags);
>  
>  	return old;
>  }
> @@ -441,6 +452,7 @@ int swap_cgroup_swapon(int type, unsigne
>  	mutex_lock(&swap_cgroup_mutex);
>  	ctrl->length = length;
>  	ctrl->map = array;
> +	spin_lock_init(&ctrl->lock);
>  	if (swap_cgroup_prepare(type)) {
>  		/* memory shortage */
>  		ctrl->map = NULL;
> 
> --
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Re: [BUGFIX][PATCH] memcg: avoid use cmpxchg in swap cgroup maintainance (Was Re: 34-rc1-git3 build failure with CGROUP_MEM_RES_CTLR_SWAP=y

[Benjamin Herrenschmidt]

> Oh..ok, powerpc (and other archs?) can't do 2byte cmpxchg and xchg.
> Then, we should use spinlock rather than that.
> 
> How about this ? Nishimura-san, could you consider something better ?
> We need a quick fix.

sparc64 is the same as powerpc in that regard, maybe others. 

Cheers,
Ben.

> ==
> swap_cgroup uses 2bytes data and uses cmpxchg in a new operation.
> 2byte cmpxchg/xchg is not available on some archs. This patch replaces
> cmpxchg/xchg with operations under lock.
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> ---
>  mm/page_cgroup.c |   20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
> 
> Index: mmotm-2.6.34-Mar11/mm/page_cgroup.c
> ===================================================================
> --- mmotm-2.6.34-Mar11.orig/mm/page_cgroup.c
> +++ mmotm-2.6.34-Mar11/mm/page_cgroup.c
> @@ -284,6 +284,7 @@ static DEFINE_MUTEX(swap_cgroup_mutex);
>  struct swap_cgroup_ctrl {
>  	struct page **map;
>  	unsigned long length;
> +	spinlock_t	lock;
>  };
>  
>  struct swap_cgroup_ctrl swap_cgroup_ctrl[MAX_SWAPFILES];
> @@ -353,16 +354,22 @@ unsigned short swap_cgroup_cmpxchg(swp_e
>  	struct swap_cgroup_ctrl *ctrl;
>  	struct page *mappage;
>  	struct swap_cgroup *sc;
> +	unsigned long flags;
> +	unsigned short retval;
>  
>  	ctrl = &swap_cgroup_ctrl[type];
>  
>  	mappage = ctrl->map[idx];
>  	sc = page_address(mappage);
>  	sc += pos;
> -	if (cmpxchg(&sc->id, old, new) == old)
> -		return old;
> +	spin_lock_irqsave(&ctrl->lock, flags);
> +	retval = sc->id;
> +	if (retval == old)
> +		sc->id = new;
>  	else
> -		return 0;
> +		retval = 0;
> +	spin_unlock_irqrestore(&ctrl->lock, flags);
> +	return retval;
>  }
>  
>  /**
> @@ -383,13 +390,17 @@ unsigned short swap_cgroup_record(swp_en
>  	struct page *mappage;
>  	struct swap_cgroup *sc;
>  	unsigned short old;
> +	unsigned long flags;
>  
>  	ctrl = &swap_cgroup_ctrl[type];
>  
>  	mappage = ctrl->map[idx];
>  	sc = page_address(mappage);
>  	sc += pos;
> -	old = xchg(&sc->id, id);
> +	spin_lock_irqsave(&ctrl->lock, flags);
> +	old = sc->id;
> +	sc->id = id;
> +	spin_unlock_irqrestore(&ctrl->lock, flags);
>  
>  	return old;
>  }
> @@ -441,6 +452,7 @@ int swap_cgroup_swapon(int type, unsigne
>  	mutex_lock(&swap_cgroup_mutex);
>  	ctrl->length = length;
>  	ctrl->map = array;
> +	spin_lock_init(&ctrl->lock);
>  	if (swap_cgroup_prepare(type)) {
>  		/* memory shortage */
>  		ctrl->map = NULL;
> 
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