linux-kernel - Re: [v6 15/15] mm: debug for raw alloctor

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Date:   Fri, 11 Aug 2017 15:08:31 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Pavel Tatashin <pasha.tatashin@...cle.com>
Cc:     linux-kernel@...r.kernel.org, sparclinux@...r.kernel.org,
        linux-mm@...ck.org, linuxppc-dev@...ts.ozlabs.org,
        linux-s390@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        x86@...nel.org, kasan-dev@...glegroups.com, borntraeger@...ibm.com,
        heiko.carstens@...ibm.com, davem@...emloft.net,
        willy@...radead.org, ard.biesheuvel@...aro.org,
        will.deacon@....com, catalin.marinas@....com, sam@...nborg.org
Subject: Re: [v6 15/15] mm: debug for raw alloctor

On Mon 07-08-17 16:38:49, Pavel Tatashin wrote:
> When CONFIG_DEBUG_VM is enabled, this patch sets all the memory that is
> returned by memblock_virt_alloc_try_nid_raw() to ones to ensure that no
> places excpect zeroed memory.

Please fold this into the patch which introduces
memblock_virt_alloc_try_nid_raw. I am not sure CONFIG_DEBUG_VM is the
best config because that tends to be enabled quite often. Maybe
CONFIG_MEMBLOCK_DEBUG? Or even make it kernel command line parameter?

> Signed-off-by: Pavel Tatashin <pasha.tatashin@...cle.com>
> Reviewed-by: Steven Sistare <steven.sistare@...cle.com>
> Reviewed-by: Daniel Jordan <daniel.m.jordan@...cle.com>
> Reviewed-by: Bob Picco <bob.picco@...cle.com>
> ---
>  mm/memblock.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 3fbf3bcb52d9..29fcb1dd8a81 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -1363,12 +1363,19 @@ void * __init memblock_virt_alloc_try_nid_raw(
>  			phys_addr_t min_addr, phys_addr_t max_addr,
>  			int nid)
>  {
> +	void *ptr;
> +
>  	memblock_dbg("%s: %llu bytes align=0x%llx nid=%d from=0x%llx max_addr=0x%llx %pF\n",
>  		     __func__, (u64)size, (u64)align, nid, (u64)min_addr,
>  		     (u64)max_addr, (void *)_RET_IP_);
>  
> -	return memblock_virt_alloc_internal(size, align,
> -					    min_addr, max_addr, nid);
> +	ptr = memblock_virt_alloc_internal(size, align,
> +					   min_addr, max_addr, nid);
> +#ifdef CONFIG_DEBUG_VM
> +	if (ptr && size > 0)
> +		memset(ptr, 0xff, size);
> +#endif
> +	return ptr;
>  }
>  
>  /**
> -- 
> 2.14.0

-- 
Michal Hocko
SUSE Labs