Re: [PATCH v2] mm: kmemleak: Avoid using __va() on addresses that don't have a lowmem mapping

[Vignesh R]

On Wednesday 17 August 2016 02:58 PM, Catalin Marinas wrote:
> Some of the kmemleak_*() callbacks in memblock, bootmem, CMA convert a
> physical address to a virtual one using __va(). However, such physical
> addresses may sometimes be located in highmem and using __va() is
> incorrect, leading to inconsistent object tracking in kmemleak.
> 
> The following functions have been added to the kmemleak API and they
> take a physical address as the object pointer. They only perform the
> corresponding action if the address has a lowmem mapping:
> 
> kmemleak_alloc_phys
> kmemleak_free_part_phys
> kmemleak_not_leak_phys
> kmemleak_ignore_phys
> 
> The affected calling places have been updated to use the new kmemleak
> API.
> 
> Reported-by: Vignesh R <vigneshr@xxxxxx>
> Cc: Vignesh R <vigneshr@xxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> ---
> 
> v1 -> v2:
>   Moved the kmemleak_*_phys() functions out of line to avoid including
>   linux/mm.h in linux/kmemleak.h and cause build errors on several platforms
> 
> Vignesh, I removed your tested/acked tags since this patch has been modified
> slightly. Could you please give it another try? Thank you.

Tested on AM335x EVM and DRA72 EVM on top of linux-next:
Tested-by: Vignesh R <vigneshr@xxxxxx>

Thanks
Vignesh

> 
>  Documentation/kmemleak.txt |  9 +++++++++
>  include/linux/kmemleak.h   | 18 ++++++++++++++++++
>  mm/bootmem.c               |  6 +++---
>  mm/cma.c                   |  2 +-
>  mm/kmemleak.c              | 45 +++++++++++++++++++++++++++++++++++++++++++++
>  mm/memblock.c              |  8 ++++----
>  mm/nobootmem.c             |  2 +-
>  7 files changed, 81 insertions(+), 9 deletions(-)
> 
> diff --git a/Documentation/kmemleak.txt b/Documentation/kmemleak.txt
> index 18e24abb3ecf..35e1a8891e3a 100644
> --- a/Documentation/kmemleak.txt
> +++ b/Documentation/kmemleak.txt
> @@ -155,6 +155,15 @@ kmemleak_erase		 - erase an old value in a pointer variable
>  kmemleak_alloc_recursive - as kmemleak_alloc but checks the recursiveness
>  kmemleak_free_recursive	 - as kmemleak_free but checks the recursiveness
>  
> +The following functions take a physical address as the object pointer
> +and only perform the corresponding action if the address has a lowmem
> +mapping:
> +
> +kmemleak_alloc_phys
> +kmemleak_free_part_phys
> +kmemleak_not_leak_phys
> +kmemleak_ignore_phys
> +
>  Dealing with false positives/negatives
>  --------------------------------------
>  
> diff --git a/include/linux/kmemleak.h b/include/linux/kmemleak.h
> index 4894c6888bc6..1c2a32829620 100644
> --- a/include/linux/kmemleak.h
> +++ b/include/linux/kmemleak.h
> @@ -38,6 +38,11 @@ extern void kmemleak_not_leak(const void *ptr) __ref;
>  extern void kmemleak_ignore(const void *ptr) __ref;
>  extern void kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp) __ref;
>  extern void kmemleak_no_scan(const void *ptr) __ref;
> +extern void kmemleak_alloc_phys(phys_addr_t phys, size_t size, int min_count,
> +				gfp_t gfp) __ref;
> +extern void kmemleak_free_part_phys(phys_addr_t phys, size_t size) __ref;
> +extern void kmemleak_not_leak_phys(phys_addr_t phys) __ref;
> +extern void kmemleak_ignore_phys(phys_addr_t phys) __ref;
>  
>  static inline void kmemleak_alloc_recursive(const void *ptr, size_t size,
>  					    int min_count, unsigned long flags,
> @@ -106,6 +111,19 @@ static inline void kmemleak_erase(void **ptr)
>  static inline void kmemleak_no_scan(const void *ptr)
>  {
>  }
> +static inline void kmemleak_alloc_phys(phys_addr_t phys, size_t size,
> +				       int min_count, gfp_t gfp)
> +{
> +}
> +static inline void kmemleak_free_part_phys(phys_addr_t phys, size_t size)
> +{
> +}
> +static inline void kmemleak_not_leak_phys(phys_addr_t phys)
> +{
> +}
> +static inline void kmemleak_ignore_phys(phys_addr_t phys)
> +{
> +}
>  
>  #endif	/* CONFIG_DEBUG_KMEMLEAK */
>  
> diff --git a/mm/bootmem.c b/mm/bootmem.c
> index 0aa7dda52402..80f1d70bad2d 100644
> --- a/mm/bootmem.c
> +++ b/mm/bootmem.c
> @@ -158,7 +158,7 @@ void __init free_bootmem_late(unsigned long physaddr, unsigned long size)
>  {
>  	unsigned long cursor, end;
>  
> -	kmemleak_free_part(__va(physaddr), size);
> +	kmemleak_free_part_phys(physaddr, size);
>  
>  	cursor = PFN_UP(physaddr);
>  	end = PFN_DOWN(physaddr + size);
> @@ -402,7 +402,7 @@ void __init free_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
>  {
>  	unsigned long start, end;
>  
> -	kmemleak_free_part(__va(physaddr), size);
> +	kmemleak_free_part_phys(physaddr, size);
>  
>  	start = PFN_UP(physaddr);
>  	end = PFN_DOWN(physaddr + size);
> @@ -423,7 +423,7 @@ void __init free_bootmem(unsigned long physaddr, unsigned long size)
>  {
>  	unsigned long start, end;
>  
> -	kmemleak_free_part(__va(physaddr), size);
> +	kmemleak_free_part_phys(physaddr, size);
>  
>  	start = PFN_UP(physaddr);
>  	end = PFN_DOWN(physaddr + size);
> diff --git a/mm/cma.c b/mm/cma.c
> index bd0e1412475e..384c2cb51b56 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -336,7 +336,7 @@ int __init cma_declare_contiguous(phys_addr_t base,
>  		 * kmemleak scans/reads tracked objects for pointers to other
>  		 * objects but this address isn't mapped and accessible
>  		 */
> -		kmemleak_ignore(phys_to_virt(addr));
> +		kmemleak_ignore_phys(addr);
>  		base = addr;
>  	}
>  
> diff --git a/mm/kmemleak.c b/mm/kmemleak.c
> index 086292f7c59d..4a717788998b 100644
> --- a/mm/kmemleak.c
> +++ b/mm/kmemleak.c
> @@ -1121,6 +1121,51 @@ void __ref kmemleak_no_scan(const void *ptr)
>  }
>  EXPORT_SYMBOL(kmemleak_no_scan);
>  
> +/**
> + * kmemleak_alloc_phys - similar to kmemleak_alloc but taking a physical
> + *			 address argument
> + */
> +void __ref kmemleak_alloc_phys(phys_addr_t phys, size_t size, int min_count,
> +			       gfp_t gfp)
> +{
> +	if (!IS_ENABLED(CONFIG_HIGHMEM) || phys < __pa(high_memory))
> +		kmemleak_alloc(__va(phys), size, min_count, gfp);
> +}
> +EXPORT_SYMBOL(kmemleak_alloc_phys);
> +
> +/**
> + * kmemleak_free_part_phys - similar to kmemleak_free_part but taking a
> + *			     physical address argument
> + */
> +void __ref kmemleak_free_part_phys(phys_addr_t phys, size_t size)
> +{
> +	if (!IS_ENABLED(CONFIG_HIGHMEM) || phys < __pa(high_memory))
> +		kmemleak_free_part(__va(phys), size);
> +}
> +EXPORT_SYMBOL(kmemleak_free_part_phys);
> +
> +/**
> + * kmemleak_not_leak_phys - similar to kmemleak_not_leak but taking a physical
> + *			    address argument
> + */
> +void __ref kmemleak_not_leak_phys(phys_addr_t phys)
> +{
> +	if (!IS_ENABLED(CONFIG_HIGHMEM) || phys < __pa(high_memory))
> +		kmemleak_not_leak(__va(phys));
> +}
> +EXPORT_SYMBOL(kmemleak_not_leak_phys);
> +
> +/**
> + * kmemleak_ignore_phys - similar to kmemleak_ignore but taking a physical
> + *			  address argument
> + */
> +void __ref kmemleak_ignore_phys(phys_addr_t phys)
> +{
> +	if (!IS_ENABLED(CONFIG_HIGHMEM) || phys < __pa(high_memory))
> +		kmemleak_ignore(__va(phys));
> +}
> +EXPORT_SYMBOL(kmemleak_ignore_phys);
> +
>  /*
>   * Update an object's checksum and return true if it was modified.
>   */
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 483197ef613f..30ecea7b45d1 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -723,7 +723,7 @@ int __init_memblock memblock_free(phys_addr_t base, phys_addr_t size)
>  		     (unsigned long long)base + size - 1,
>  		     (void *)_RET_IP_);
>  
> -	kmemleak_free_part(__va(base), size);
> +	kmemleak_free_part_phys(base, size);
>  	return memblock_remove_range(&memblock.reserved, base, size);
>  }
>  
> @@ -1152,7 +1152,7 @@ static phys_addr_t __init memblock_alloc_range_nid(phys_addr_t size,
>  		 * The min_count is set to 0 so that memblock allocations are
>  		 * never reported as leaks.
>  		 */
> -		kmemleak_alloc(__va(found), size, 0, 0);
> +		kmemleak_alloc_phys(found, size, 0, 0);
>  		return found;
>  	}
>  	return 0;
> @@ -1399,7 +1399,7 @@ void __init __memblock_free_early(phys_addr_t base, phys_addr_t size)
>  	memblock_dbg("%s: [%#016llx-%#016llx] %pF\n",
>  		     __func__, (u64)base, (u64)base + size - 1,
>  		     (void *)_RET_IP_);
> -	kmemleak_free_part(__va(base), size);
> +	kmemleak_free_part_phys(base, size);
>  	memblock_remove_range(&memblock.reserved, base, size);
>  }
>  
> @@ -1419,7 +1419,7 @@ void __init __memblock_free_late(phys_addr_t base, phys_addr_t size)
>  	memblock_dbg("%s: [%#016llx-%#016llx] %pF\n",
>  		     __func__, (u64)base, (u64)base + size - 1,
>  		     (void *)_RET_IP_);
> -	kmemleak_free_part(__va(base), size);
> +	kmemleak_free_part_phys(base, size);
>  	cursor = PFN_UP(base);
>  	end = PFN_DOWN(base + size);
>  
> diff --git a/mm/nobootmem.c b/mm/nobootmem.c
> index bd05a70f44b9..a056d31dff7e 100644
> --- a/mm/nobootmem.c
> +++ b/mm/nobootmem.c
> @@ -81,7 +81,7 @@ void __init free_bootmem_late(unsigned long addr, unsigned long size)
>  {
>  	unsigned long cursor, end;
>  
> -	kmemleak_free_part(__va(addr), size);
> +	kmemleak_free_part_phys(addr, size);
>  
>  	cursor = PFN_UP(addr);
>  	end = PFN_DOWN(addr + size);
> 

-- 
Regards
Vignesh