[PATCH] percpu: fix a memory leak in pcpu_extend_area_map()

[PATCH] percpu: fix a memory leak in pcpu_extend_area_map()

[Tejun Heo]

>From 206c53730b8b1707becca7a868ea8d14ebee24d2 Mon Sep 17 00:00:00 2001
From: Huang Shijie <shijie8@gmail.com>
Date: Sun, 8 Aug 2010 14:39:07 +0200

The original code did not free the old map.  This patch fixes it.

tj: use @old as memcpy source instead of @chunk->map, and indentation
    and description update

Signed-off-by: Huang Shijie <shijie8@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
---
Patch applied to percpu#for-linus w/ some updates.  Thanks a lot for
catching this.

 mm/percpu.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/mm/percpu.c b/mm/percpu.c
index e61dc2c..a1830d8 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -393,7 +393,9 @@ static int pcpu_extend_area_map(struct pcpu_chunk *chunk, int new_alloc)
 		goto out_unlock;

 	old_size = chunk->map_alloc * sizeof(chunk->map[0]);
-	memcpy(new, chunk->map, old_size);
+	old = chunk->map;
+
+	memcpy(new, old, old_size);

 	chunk->map_alloc = new_alloc;
 	chunk->map = new;
-- 
1.7.1

Re: [PATCH] percpu: fix a memory leak in pcpu_extend_area_map()

[Andrew Morton]

On Sun, 08 Aug 2010 14:42:57 +0200
Tejun Heo <tj@kernel.org> wrote:

> >From 206c53730b8b1707becca7a868ea8d14ebee24d2 Mon Sep 17 00:00:00 2001
> From: Huang Shijie <shijie8@gmail.com>
> Date: Sun, 8 Aug 2010 14:39:07 +0200
> 
> The original code did not free the old map.  This patch fixes it.
> 
> tj: use @old as memcpy source instead of @chunk->map, and indentation
>     and description update
> 
> Signed-off-by: Huang Shijie <shijie8@gmail.com>
> Signed-off-by: Tejun Heo <tj@kernel.org>

Should have had a cc:stable in the changelog, IMO.

> ---
> Patch applied to percpu#for-linus w/ some updates.  Thanks a lot for
> catching this.
> 

This patch appears to have been lost?

> diff --git a/mm/percpu.c b/mm/percpu.c
> index e61dc2c..a1830d8 100644
> --- a/mm/percpu.c
> +++ b/mm/percpu.c
> @@ -393,7 +393,9 @@ static int pcpu_extend_area_map(struct pcpu_chunk *chunk, int new_alloc)
>  		goto out_unlock;
> 
>  	old_size = chunk->map_alloc * sizeof(chunk->map[0]);
> -	memcpy(new, chunk->map, old_size);
> +	old = chunk->map;
> +
> +	memcpy(new, old, old_size);
> 
>  	chunk->map_alloc = new_alloc;
>  	chunk->map = new;

Re: [PATCH] percpu: fix a memory leak in pcpu_extend_area_map()

[Tejun Heo]

Hello,

On 08/27/2010 12:10 AM, Andrew Morton wrote:
>> Patch applied to percpu#for-linus w/ some updates.  Thanks a lot for
>> catching this.
> 
> This patch appears to have been lost?

It has been in percpu#for-linus.  Given the way percpu allocator is
currently used, the bug isn't likely to cause any real leakage, so I
was waiting a bit before pushing it out.  I'll push it today.

Thanks.

-- 
tejun

breaks 2.6.32.21+ (was: [PATCH] percpu: fix a memory leak in pcpu_extend_area_map())

[Peter Palfrader]

Hey,

The patch quoted below seems to have made it into Greg's stable-queue
for 2.6.32.

I tried building a kernel based on 2.6.32.21 plus all the patches
currently in that queue.  The resulting kernel unfortunately didn't
boot for me, neither as a 32 nor as 64 bit x86 kernel.

I have put up a screenshot of a trace at
http://asteria.noreply.org/~weasel/volatile/2010-09-16-SrLl9JHtDTg/trace-64bit.png
since the kernel fortunately also died in kvm - unfortunately only the
last 60 lines are easily available.  If you need more I could try to set
up some serial console thing to catch more.

Bisecting led to this patch and reverting "percpu: fix a memory leak in
pcpu_extend_area_map()" makes the kernel boot for me again.

> From 206c53730b8b1707becca7a868ea8d14ebee24d2 Mon Sep 17 00:00:00 2001
> From: Huang Shijie <shijie8@gmail.com>
> Date: Sun, 8 Aug 2010 14:39:07 +0200
> 
> The original code did not free the old map.  This patch fixes it.
> 
> tj: use @old as memcpy source instead of @chunk->map, and indentation
>     and description update
> 
> Signed-off-by: Huang Shijie <shijie8@gmail.com>
> Signed-off-by: Tejun Heo <tj@kernel.org>
> ---
> Patch applied to percpu#for-linus w/ some updates.  Thanks a lot for
> catching this.
> 
>  mm/percpu.c |    4 +++-
>  1 files changed, 3 insertions(+), 1 deletions(-)
> 
> diff --git a/mm/percpu.c b/mm/percpu.c
> index e61dc2c..a1830d8 100644
> --- a/mm/percpu.c
> +++ b/mm/percpu.c
> @@ -393,7 +393,9 @@ static int pcpu_extend_area_map(struct pcpu_chunk *chunk, int new_alloc)
>  		goto out_unlock;
> 
>  	old_size = chunk->map_alloc * sizeof(chunk->map[0]);
> -	memcpy(new, chunk->map, old_size);
> +	old = chunk->map;
> +
> +	memcpy(new, old, old_size);
> 
>  	chunk->map_alloc = new_alloc;
>  	chunk->map = new;

Cheers,
Peter
-- 
                           |  .''`.  ** Debian GNU/Linux **
      Peter Palfrader      | : :' :      The  universal
 http://www.palfrader.org/ | `. `'      Operating System
                           |   `-    http://www.debian.org/

Re: [stable] breaks 2.6.32.21+ (was: [PATCH] percpu: fix a memory leak in pcpu_extend_area_map())

[Greg KH]

On Thu, Sep 16, 2010 at 11:36:03PM +0200, Peter Palfrader wrote:
> Hey,
> 
> The patch quoted below seems to have made it into Greg's stable-queue
> for 2.6.32.
> 
> I tried building a kernel based on 2.6.32.21 plus all the patches
> currently in that queue.  The resulting kernel unfortunately didn't
> boot for me, neither as a 32 nor as 64 bit x86 kernel.
> 
> I have put up a screenshot of a trace at
> http://asteria.noreply.org/~weasel/volatile/2010-09-16-SrLl9JHtDTg/trace-64bit.png
> since the kernel fortunately also died in kvm - unfortunately only the
> last 60 lines are easily available.  If you need more I could try to set
> up some serial console thing to catch more.
> 
> Bisecting led to this patch and reverting "percpu: fix a memory leak in
> pcpu_extend_area_map()" makes the kernel boot for me again.

Odd, someone just reported the same problem for .35-stable as well.

Tejun, what's going on here?

thanks,

greg k-h

> 
> > From 206c53730b8b1707becca7a868ea8d14ebee24d2 Mon Sep 17 00:00:00 2001
> > From: Huang Shijie <shijie8@gmail.com>
> > Date: Sun, 8 Aug 2010 14:39:07 +0200
> > 
> > The original code did not free the old map.  This patch fixes it.
> > 
> > tj: use @old as memcpy source instead of @chunk->map, and indentation
> >     and description update
> > 
> > Signed-off-by: Huang Shijie <shijie8@gmail.com>
> > Signed-off-by: Tejun Heo <tj@kernel.org>
> > ---
> > Patch applied to percpu#for-linus w/ some updates.  Thanks a lot for
> > catching this.
> > 
> >  mm/percpu.c |    4 +++-
> >  1 files changed, 3 insertions(+), 1 deletions(-)
> > 
> > diff --git a/mm/percpu.c b/mm/percpu.c
> > index e61dc2c..a1830d8 100644
> > --- a/mm/percpu.c
> > +++ b/mm/percpu.c
> > @@ -393,7 +393,9 @@ static int pcpu_extend_area_map(struct pcpu_chunk *chunk, int new_alloc)
> >  		goto out_unlock;
> > 
> >  	old_size = chunk->map_alloc * sizeof(chunk->map[0]);
> > -	memcpy(new, chunk->map, old_size);
> > +	old = chunk->map;
> > +
> > +	memcpy(new, old, old_size);
> > 
> >  	chunk->map_alloc = new_alloc;
> >  	chunk->map = new;
> 
> Cheers,
> Peter
> -- 
>                            |  .''`.  ** Debian GNU/Linux **
>       Peter Palfrader      | : :' :      The  universal
>  http://www.palfrader.org/ | `. `'      Operating System
>                            |   `-    http://www.debian.org/
> 
> _______________________________________________
> stable mailing list
> stable@linux.kernel.org
> http://linux.kernel.org/mailman/listinfo/stable

Re: [stable] breaks 2.6.32.21+

[Tejun Heo]

On 09/17/2010 01:13 AM, Greg KH wrote:
> Odd, someone just reported the same problem for .35-stable as well.
> 
> Tejun, what's going on here?

Please drop it.  The memory leak was introduced after 2.6.36-rc1.  I
got confused which commit was in which kernel.  I'll be more careful
with stable cc's.  Sorry about that.

-- 
tejun

Re: [stable] breaks 2.6.32.21+

[Greg KH]

On Fri, Sep 17, 2010 at 03:47:35PM +0200, Tejun Heo wrote:
> On 09/17/2010 01:13 AM, Greg KH wrote:
> > Odd, someone just reported the same problem for .35-stable as well.
> > 
> > Tejun, what's going on here?
> 
> Please drop it.  The memory leak was introduced after 2.6.36-rc1.  I
> got confused which commit was in which kernel.  I'll be more careful
> with stable cc's.  Sorry about that.

No problem, now dropped.

thanks,

greg k-h