linux-kernel - Re: [patch] do_no

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4517A1D9.2090505@sgi.com>
Date:	Mon, 25 Sep 2006 11:31:05 +0200
From:	Jes Sorensen <jes@....com>
To:	Andrew Morton <akpm@...l.org>
Cc:	Linus Torvalds <torvalds@...l.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	bjorn_helgaas@...com, Nick Piggin <nickpiggin@...oo.com.au>,
	Robin Holt <holt@....com>, Dean Nelson <dcn@....com>,
	Hugh Dickins <hugh@...itas.com>
Subject: Re: [patch] do_no_pfn()

Andrew Morton wrote:

> How does this followup look?
> 
> We don't want the rarely-used do_no_pfn() to get inlined in the oft-used
> handle_pte_fault(), using up icache.  Mark it noinline and unlikely.


I'd say it looks good - will give a microscopic slowdown for do_no_pfn
but compared to the overall benefit I think thats more than acceptable.

Acked-by: Jes Sorensen <jes@....com>

Cheers,
Jes

> --- a/mm/memory.c~do_no_pfn-tweaks
> +++ a/mm/memory.c
> @@ -2276,8 +2276,10 @@ oom:
>   *
>   * It is expected that the ->nopfn handler always returns the same pfn
>   * for a given virtual mapping.
> + *
> + * Mark this `noinline' to prevent it from bloating the main pagefault code.
>   */
> -static int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma,
> +static noinline int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma,
>  		     unsigned long address, pte_t *page_table, pmd_t *pmd,
>  		     int write_access)
>  {
> @@ -2376,7 +2378,7 @@ static inline int handle_pte_fault(struc
>  					return do_no_page(mm, vma, address,
>  							  pte, pmd,
>  							  write_access);
> -				if (vma->vm_ops->nopfn)
> +				if (unlikely(vma->vm_ops->nopfn))
>  					return do_no_pfn(mm, vma, address, pte,
>  							 pmd, write_access);
>  			}
> _

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/