linux-kernel - Re: [PATCH 1/3] vmalloc: Add __vmalloc_node_try

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Message-ID: <12014310-19f7-dc31-d983-9c7e00c8b446@infradead.org>
Date:   Wed, 20 Jun 2018 15:16:50 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Rick Edgecombe <rick.p.edgecombe@...el.com>, tglx@...utronix.de,
        mingo@...hat.com, hpa@...or.com, x86@...nel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        kernel-hardening@...ts.openwall.com
Cc:     kristen.c.accardi@...el.com, dave.hansen@...el.com,
        arjan.van.de.ven@...el.com
Subject: Re: [PATCH 1/3] vmalloc: Add __vmalloc_node_try_addr function

On 06/20/2018 03:09 PM, Rick Edgecombe wrote:
> Create __vmalloc_node_try_addr function that tries to allocate at a specific
> address.  The implementation relies on __vmalloc_node_range for the bulk of the
> work.  To keep this function from spamming the logs when an allocation failure
> is fails, __vmalloc_node_range is changed to only warn when __GFP_NOWARN is not
> set.  This behavior is consistent with this flags interpretation in
> alloc_vmap_area.
> 
> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
> ---
>  include/linux/vmalloc.h |  3 +++
>  mm/vmalloc.c            | 41 +++++++++++++++++++++++++++++++++++++++--
>  2 files changed, 42 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> index 398e9c9..6eaa896 100644
> --- a/include/linux/vmalloc.h
> +++ b/include/linux/vmalloc.h
> @@ -82,6 +82,9 @@ extern void *__vmalloc_node_range(unsigned long size, unsigned long align,
>  			unsigned long start, unsigned long end, gfp_t gfp_mask,
>  			pgprot_t prot, unsigned long vm_flags, int node,
>  			const void *caller);
> +extern void *__vmalloc_node_try_addr(unsigned long addr, unsigned long size,
> +			gfp_t gfp_mask,	pgprot_t prot, unsigned long vm_flags,
> +			int node, const void *caller);
>  #ifndef CONFIG_MMU
>  extern void *__vmalloc_node_flags(unsigned long size, int node, gfp_t flags);
>  static inline void *__vmalloc_node_flags_caller(unsigned long size, int node,

> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index cfea25b..9e0820c9 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1710,6 +1710,42 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
>  }
>  
>  /**
> + *	__vmalloc_try_addr  -  try to alloc at a specific address

    *   __vmalloc_node_try_addr - try to allocate at a specific address

> + *	@addr:		address to try
> + *	@size:		size to try
> + *	@gfp_mask:	flags for the page level allocator
> + *	@prot:		protection mask for the allocated pages
> + *	@vm_flags:	additional vm area flags (e.g. %VM_NO_GUARD)
> + *	@node:		node to use for allocation or NUMA_NO_NODE
> + *	@caller:	caller's return address
> + *
> + *	Try to allocate at the specific address. If it succeeds the address is
> + *	returned. If it fails NULL is returned.  It may trigger TLB flushes.
> + */
> +void *__vmalloc_node_try_addr(unsigned long addr, unsigned long size,
> +			gfp_t gfp_mask,	pgprot_t prot, unsigned long vm_flags,
> +			int node, const void *caller)
> +{

so this isn't optional, eh?  You are going to force it on people because?

thanks,
-- 
~Randy