Subject: Re: mm/slab: ppc: ubi: kmalloc_slab WARNING / PPC + UBI driver

From: Wladislav Wiebe <[email-masked]>
Date: Wed, 31 Jul 2013 18:33:40 +0200

Hi Christoph,

On 31/07/13 17:45, Christoph Lameter wrote:
> Crap you cannot do PAGE_SIZE allocations with kmalloc_large. Fails when
> freeing pages. Need to only do the multiple page allocs with
> kmalloc_large.
> 
> Subject: seq_file: Use kmalloc_large for page sized allocation
> 
> There is no point in using the slab allocation functions for
> large page order allocation. Use kmalloc_large().
> 
> This fixes the warning about large allocs but it will still cause
> large contiguous allocs that could fail because of memory fragmentation.

Thanks for the point, do you plan to make kmalloc_large available for extern access in a separate mainline patch?
Since kmalloc_large is statically defined in slub_def.h and when including it to seq_file.c
we have a lot of conflicting types:
..
In file included from ../linux/fs/seq_file.c:8:0:
../linux/include/linux/slub_def.h: In function 'kmalloc':
../linux/include/linux/slub_def.h:161:14: error: 'KMALLOC_MAX_CACHE_SIZE' undeclared (first use in this function)
../results/linux/include/linux/slub_def.h:161:14: note: each undeclared identifier is reported only once for each function it appears in
../linux/include/linux/slub_def.h:165:4: error: implicit declaration of function 'kmalloc_index' [-Werror=implicit-function-declaration]
../linux/include/linux/slub_def.h:168:12: error: 'ZERO_SIZE_PTR' undeclared (first use in this function)
../linux/include/linux/slub_def.h:170:34: error: 'kmalloc_caches' undeclared (first use in this function)
..

Thanks & BR
Wladislav Wiebe

> 
> Signed-off-by: Christoph Lameter <[email-masked]>
> 
> Index: linux/fs/seq_file.c
> ===================================================================
> --- linux.orig/fs/seq_file.c	2013-07-31 10:39:03.050472030 -0500
> +++ linux/fs/seq_file.c	2013-07-31 10:39:03.050472030 -0500
> @@ -136,7 +136,7 @@ static int traverse(struct seq_file *m,
>  Eoverflow:
>  	m->op->stop(m, p);
>  	kfree(m->buf);
> -	m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
> +	m->buf = kmalloc_large(m->size <<= 1, GFP_KERNEL);
>  	return !m->buf ? -ENOMEM : -EAGAIN;
>  }
> 
> @@ -232,7 +232,7 @@ ssize_t seq_read(struct file *file, char
>  			goto Fill;
>  		m->op->stop(m, p);
>  		kfree(m->buf);
> -		m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
> +		m->buf = kmalloc_large(m->size <<= 1, GFP_KERNEL);
>  		if (!m->buf)
>  			goto Enomem;
>  		m->count = 0;
>