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Date:   Fri, 22 Oct 2021 14:22:44 +0200
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Subject: Re: [PATCH v2 2/2] memblock: exclude MEMBLOCK_NOMAP regions from
 kmemleak
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To:     Mike Rapoport <rppt@kernel.org>, linux-mm@kvack.org
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Mike Rapoport <rppt@linux.ibm.com>,
        Qian Cai <quic_qiancai@quicinc.com>,
        Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>,
        linux-kernel@vger.kernel.org
References: <20211021070929.23272-1-rppt@kernel.org>
 <20211021070929.23272-3-rppt@kernel.org>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
In-Reply-To: <20211021070929.23272-3-rppt@kernel.org>
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On 21.10.21 09:09, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@linux.ibm.com>
> 
> Vladimir Zapolskiy reports:
> 
> commit a7259df76702 ("memblock: make memblock_find_in_range method private")
> invokes a kernel panic while running kmemleak on OF platforms with nomaped
> regions:
> 
>   Unable to handle kernel paging request at virtual address fff000021e00000
>   [...]
>     scan_block+0x64/0x170
>     scan_gray_list+0xe8/0x17c
>     kmemleak_scan+0x270/0x514
>     kmemleak_write+0x34c/0x4ac
> 
> The memory allocated from memblock is registered with kmemleak, but if it
> is marked MEMBLOCK_NOMAP it won't have linear map entries so an attempt to
> scan such areas will fault.
> 
> Ideally, memblock_mark_nomap() would inform kmemleak to ignore
> MEMBLOCK_NOMAP memory, but it can be called before kmemleak interfaces
> operating on physical addresses can use __va() conversion.
> 
> Make sure that functions that mark allocated memory as MEMBLOCK_NOMAP take
> care of informing kmemleak to ignore such memory.
> 
> Link: https://lore.kernel.org/all/8ade5174-b143-d621-8c8e-dc6a1898c6fb@linaro.org
> Link: https://lore.kernel.org/all/c30ff0a2-d196-c50d-22f0-bd50696b1205@quicinc.com
> Fixes: a7259df76702 ("memblock: make memblock_find_in_range method private")
> Reported-by: Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>
> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> ---
>  drivers/acpi/tables.c        | 3 +++
>  drivers/of/of_reserved_mem.c | 2 ++
>  mm/memblock.c                | 3 +++
>  3 files changed, 8 insertions(+)
> 
> diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
> index f9383736fa0f..71419eb16e09 100644
> --- a/drivers/acpi/tables.c
> +++ b/drivers/acpi/tables.c
> @@ -21,6 +21,7 @@
>  #include <linux/earlycpio.h>
>  #include <linux/initrd.h>
>  #include <linux/security.h>
> +#include <linux/kmemleak.h>
>  #include "internal.h"
>  
>  #ifdef CONFIG_ACPI_CUSTOM_DSDT
> @@ -601,6 +602,8 @@ void __init acpi_table_upgrade(void)
>  	 */
>  	arch_reserve_mem_area(acpi_tables_addr, all_tables_size);
>  
> +	kmemleak_ignore_phys(acpi_tables_addr);
> +
>  	/*
>  	 * early_ioremap only can remap 256k one time. If we map all
>  	 * tables one time, we will hit the limit. Need to map chunks
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> index 59c1390cdf42..9da8835ba5a5 100644
> --- a/drivers/of/of_reserved_mem.c
> +++ b/drivers/of/of_reserved_mem.c
> @@ -21,6 +21,7 @@
>  #include <linux/sort.h>
>  #include <linux/slab.h>
>  #include <linux/memblock.h>
> +#include <linux/kmemleak.h>
>  
>  #include "of_private.h"
>  
> @@ -46,6 +47,7 @@ static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
>  		err = memblock_mark_nomap(base, size);
>  		if (err)
>  			memblock_free(base, size);
> +		kmemleak_ignore_phys(base);
>  	}
>  
>  	return err;
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 184dcd2e5d99..dab804b09d62 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -932,6 +932,9 @@ int __init_memblock memblock_mark_mirror(phys_addr_t base, phys_addr_t size)
>   * covered by the memory map. The struct page representing NOMAP memory
>   * frames in the memory map will be PageReserved()
>   *
> + * Note: if the memory being marked %MEMBLOCK_NOMAP was allocated from
> + * memblock, the caller must inform kmemleak to ignore that memory
> + *
>   * Return: 0 on success, -errno on failure.
>   */
>  int __init_memblock memblock_mark_nomap(phys_addr_t base, phys_addr_t size)
> 

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb