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DateFri, 04 Mar 2005 09:48:41 +0200
FromJustin Schoeman <>
SubjectRe: Tracing memory leaks (slabs) in 2.6.9+ kernels?
Thanks everybody for your help.  I have at least located the site of the 
leak - now I just need to find out why the destructor is not being 
called ;-).

Will the slab debugger make it into the kernel as a standard compile 
time option?  It is a _really_ usefull tool to have around.

Thanks again,
Justin

Andrew Morton wrote:
> Justin Schoeman <justin@expertron.co.za> wrote:
> 
>>OK - I have the patch working now, but there seems to be a flaw in the 
>> address reporting. When I look up the reported address in 
>> /proc/kallsyms, then look in the objdump of the module, the reported 
>> adress _does_not_ point to a call.
>>
>> Am I missing something simple here?
> 
> 
> Use the latest version of the patch (below).  Link the module into the
> kernel.  Enable CONFIG_KALLSYMS.
> 
> --- 25/include/asm-alpha/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-alpha/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -56,7 +56,7 @@ typedef unsigned long u64;
>  typedef u64 dma_addr_t;
>  typedef u64 dma64_addr_t;
> 
> -typedef unsigned short kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #endif /* __ASSEMBLY__ */
>  #endif /* __KERNEL__ */
> diff -puN include/asm-arm26/types.h~slab-leak-detector include/asm-arm26/types.h
> --- 25/include/asm-arm26/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-arm26/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -52,7 +52,7 @@ typedef unsigned long long u64;
>  typedef u32 dma_addr_t;
>  typedef u32 dma64_addr_t;
> 
> -typedef unsigned int kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #endif /* __ASSEMBLY__ */
> 
> diff -puN include/asm-arm/types.h~slab-leak-detector include/asm-arm/types.h
> --- 25/include/asm-arm/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-arm/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -52,7 +52,7 @@ typedef unsigned long long u64;
>  typedef u32 dma_addr_t;
>  typedef u32 dma64_addr_t;
> 
> -typedef unsigned int kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #endif /* __ASSEMBLY__ */
> 
> diff -puN include/asm-cris/types.h~slab-leak-detector include/asm-cris/types.h
> --- 25/include/asm-cris/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-cris/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -52,7 +52,7 @@ typedef unsigned long long u64;
>  typedef u32 dma_addr_t;
>  typedef u32 dma64_addr_t;
> 
> -typedef unsigned int kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #endif /* __ASSEMBLY__ */
> 
> diff -puN include/asm-frv/types.h~slab-leak-detector include/asm-frv/types.h
> --- 25/include/asm-frv/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-frv/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -65,7 +65,7 @@ typedef u64 u_quad_t;
> 
>  typedef u32 dma_addr_t;
> 
> -typedef unsigned short kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #endif /* __ASSEMBLY__ */
> 
> diff -puN include/asm-h8300/types.h~slab-leak-detector include/asm-h8300/types.h
> --- 25/include/asm-h8300/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-h8300/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -58,7 +58,7 @@ typedef u32 dma_addr_t;
>  #define HAVE_SECTOR_T
>  typedef u64 sector_t;
> 
> -typedef unsigned int kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #endif /* __KERNEL__ */
> 
> diff -puN include/asm-i386/types.h~slab-leak-detector include/asm-i386/types.h
> --- 25/include/asm-i386/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-i386/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -63,7 +63,7 @@ typedef u64 sector_t;
>  #define HAVE_SECTOR_T
>  #endif
> 
> -typedef unsigned short kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #endif /* __ASSEMBLY__ */
> 
> diff -puN include/asm-ia64/types.h~slab-leak-detector include/asm-ia64/types.h
> --- 25/include/asm-ia64/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-ia64/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -67,7 +67,7 @@ typedef __u64 u64;
> 
>  typedef u64 dma_addr_t;
> 
> -typedef unsigned short kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  # endif /* __KERNEL__ */
>  #endif /* !__ASSEMBLY__ */
> diff -puN include/asm-m32r/types.h~slab-leak-detector include/asm-m32r/types.h
> --- 25/include/asm-m32r/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-m32r/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -55,7 +55,7 @@ typedef unsigned long long u64;
>  typedef u32 dma_addr_t;
>  typedef u64 dma64_addr_t;
> 
> -typedef unsigned short kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #endif /* __ASSEMBLY__ */
> 
> diff -puN include/asm-m68k/types.h~slab-leak-detector include/asm-m68k/types.h
> --- 25/include/asm-m68k/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-m68k/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -60,7 +60,7 @@ typedef unsigned long long u64;
>  typedef u32 dma_addr_t;
>  typedef u32 dma64_addr_t;
> 
> -typedef unsigned short kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #endif /* __ASSEMBLY__ */
> 
> diff -puN include/asm-mips/types.h~slab-leak-detector include/asm-mips/types.h
> --- 25/include/asm-mips/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-mips/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -99,7 +99,7 @@ typedef u64 sector_t;
>  #define HAVE_SECTOR_T
>  #endif
> 
> -typedef unsigned short kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #endif /* __ASSEMBLY__ */
> 
> diff -puN include/asm-parisc/types.h~slab-leak-detector include/asm-parisc/types.h
> --- 25/include/asm-parisc/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-parisc/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -56,7 +56,7 @@ typedef unsigned long long u64;
>  typedef u32 dma_addr_t;
>  typedef u64 dma64_addr_t;
> 
> -typedef unsigned int kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #endif /* __ASSEMBLY__ */
> 
> diff -puN include/asm-ppc64/types.h~slab-leak-detector include/asm-ppc64/types.h
> --- 25/include/asm-ppc64/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-ppc64/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -72,7 +72,7 @@ typedef struct {
>  	unsigned long env;
>  } func_descr_t;
> 
> -typedef unsigned int kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
>  #endif /* __ASSEMBLY__ */
> 
>  #endif /* __KERNEL__ */
> diff -puN include/asm-ppc/types.h~slab-leak-detector include/asm-ppc/types.h
> --- 25/include/asm-ppc/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-ppc/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -62,7 +62,7 @@ typedef u64 sector_t;
>  #define HAVE_SECTOR_T
>  #endif
> 
> -typedef unsigned int kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #endif /* __ASSEMBLY__ */
> 
> diff -puN include/asm-s390/types.h~slab-leak-detector include/asm-s390/types.h
> --- 25/include/asm-s390/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-s390/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -79,7 +79,7 @@ typedef unsigned  long u64;
> 
>  typedef u32 dma_addr_t;
> 
> -typedef unsigned int kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #ifndef __s390x__
>  typedef union {
> diff -puN include/asm-sh64/types.h~slab-leak-detector include/asm-sh64/types.h
> --- 25/include/asm-sh64/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-sh64/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -65,7 +65,7 @@ typedef u32 dma_addr_t;
>  #endif
>  typedef u64 dma64_addr_t;
> 
> -typedef unsigned int kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #endif /* __ASSEMBLY__ */
> 
> diff -puN include/asm-sh/types.h~slab-leak-detector include/asm-sh/types.h
> --- 25/include/asm-sh/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-sh/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -58,7 +58,7 @@ typedef u64 sector_t;
>  #define HAVE_SECTOR_T
>  #endif
> 
> -typedef unsigned int kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #endif /* __ASSEMBLY__ */
> 
> diff -puN include/asm-sparc64/types.h~slab-leak-detector include/asm-sparc64/types.h
> --- 25/include/asm-sparc64/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-sparc64/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -56,7 +56,7 @@ typedef unsigned long u64;
>  typedef u32 dma_addr_t;
>  typedef u64 dma64_addr_t;
> 
> -typedef unsigned short kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #endif /* __ASSEMBLY__ */
> 
> diff -puN include/asm-sparc/types.h~slab-leak-detector include/asm-sparc/types.h
> --- 25/include/asm-sparc/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-sparc/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -54,7 +54,7 @@ typedef unsigned long long u64;
>  typedef u32 dma_addr_t;
>  typedef u32 dma64_addr_t;
> 
> -typedef unsigned short kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #endif /* __ASSEMBLY__ */
> 
> diff -puN include/asm-v850/types.h~slab-leak-detector include/asm-v850/types.h
> --- 25/include/asm-v850/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-v850/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -59,7 +59,7 @@ typedef unsigned long long u64;
> 
>  typedef u32 dma_addr_t;
> 
> -typedef unsigned int kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #endif /* !__ASSEMBLY__ */
> 
> diff -puN include/asm-x86_64/types.h~slab-leak-detector include/asm-x86_64/types.h
> --- 25/include/asm-x86_64/types.h~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/include/asm-x86_64/types.h	2005-03-02 08:30:59.000000000 -0800
> @@ -51,7 +51,7 @@ typedef u64 dma_addr_t;
>  typedef u64 sector_t;
>  #define HAVE_SECTOR_T
> 
> -typedef unsigned short kmem_bufctl_t;
> +typedef unsigned long kmem_bufctl_t;
> 
>  #endif /* __ASSEMBLY__ */
> 
> diff -puN mm/slab.c~slab-leak-detector mm/slab.c
> --- 25/mm/slab.c~slab-leak-detector	2005-03-02 08:30:59.000000000 -0800
> +++ 25-akpm/mm/slab.c	2005-03-02 08:30:59.000000000 -0800
> @@ -2116,6 +2116,15 @@ cache_alloc_debugcheck_after(kmem_cache_
>  		*dbg_redzone1(cachep, objp) = RED_ACTIVE;
>  		*dbg_redzone2(cachep, objp) = RED_ACTIVE;
>  	}
> +	{
> +		int objnr;
> +		struct slab *slabp;
> +
> +		slabp = GET_PAGE_SLAB(virt_to_page(objp));
> +
> +		objnr = (objp - slabp->s_mem) / cachep->objsize;
> +		slab_bufctl(slabp)[objnr] = (unsigned long)caller;
> +	}
>  	objp += obj_dbghead(cachep);
>  	if (cachep->ctor && cachep->flags & SLAB_POISON) {
>  		unsigned long	ctor_flags = SLAB_CTOR_CONSTRUCTOR;
> @@ -2179,12 +2188,14 @@ static void free_block(kmem_cache_t *cac
>  		objnr = (objp - slabp->s_mem) / cachep->objsize;
>  		check_slabp(cachep, slabp);
>  #if DEBUG
> +#if 0
>  		if (slab_bufctl(slabp)[objnr] != BUFCTL_FREE) {
>  			printk(KERN_ERR "slab: double free detected in cache '%s', objp %p.\n",
>  						cachep->name, objp);
>  			BUG();
>  		}
>  #endif
> +#endif
>  		slab_bufctl(slabp)[objnr] = slabp->free;
>  		slabp->free = objnr;
>  		STATS_DEC_ACTIVE(cachep);
> @@ -2998,6 +3009,29 @@ struct seq_operations slabinfo_op = {
>  	.show	= s_show,
>  };
> 
> +static void do_dump_slabp(kmem_cache_t *cachep)
> +{
> +#if DEBUG
> +	struct list_head *q;
> +
> +	check_irq_on();
> +	spin_lock_irq(&cachep->spinlock);
> +	list_for_each(q,&cachep->lists.slabs_full) {
> +		struct slab *slabp;
> +		int i;
> +		slabp = list_entry(q, struct slab, list);
> +		for (i = 0; i < cachep->num; i++) {
> +			unsigned long sym = slab_bufctl(slabp)[i];
> +
> +			printk("obj %p/%d: %p", slabp, i, (void *)sym);
> +			print_symbol(" <%s>", sym);
> +			printk("\n");
> +		}
> +	}
> +	spin_unlock_irq(&cachep->spinlock);
> +#endif
> +}
> +
>  #define MAX_SLABINFO_WRITE 128
>  /**
>   * slabinfo_write - Tuning for the slab allocator
> @@ -3038,9 +3072,11 @@ ssize_t slabinfo_write(struct file *file
>  			    batchcount < 1 ||
>  			    batchcount > limit ||
>  			    shared < 0) {
> -				res = -EINVAL;
> +				do_dump_slabp(cachep);
> +				res = 0;
>  			} else {
> -				res = do_tune_cpucache(cachep, limit, batchcount, shared);
> +				res = do_tune_cpucache(cachep, limit,
> +							batchcount, shared);
>  			}
>  			break;
>  		}
> _
> 
> -
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