Re: [PATCH 16/36] HMM: add special swap filetype for memory migrated to HMM device memory.

[Haggai Eran]

On 21/05/2015 22:31, j.glisse@xxxxxxxxx wrote:
> From: Jerome Glisse <jglisse@xxxxxxxxxx>
> 
> When migrating anonymous memory from system memory to device memory
> CPU pte are replaced with special HMM swap entry so that page fault,
> get user page (gup), fork, ... are properly redirected to HMM helpers.
> 
> This patch only add the new swap type entry and hooks HMM helpers
> functions inside the page fault and fork code path.
> 
> Signed-off-by: JÃrÃme Glisse <jglisse@xxxxxxxxxx>
> Signed-off-by: Sherry Cheung <SCheung@xxxxxxxxxx>
> Signed-off-by: Subhash Gutti <sgutti@xxxxxxxxxx>
> Signed-off-by: Mark Hairgrove <mhairgrove@xxxxxxxxxx>
> Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
> Signed-off-by: Jatin Kumar <jakumar@xxxxxxxxxx>
> ---
>  include/linux/hmm.h     | 34 ++++++++++++++++++++++++++++++++++
>  include/linux/swap.h    | 12 +++++++++++-
>  include/linux/swapops.h | 43 ++++++++++++++++++++++++++++++++++++++++++-
>  mm/hmm.c                | 21 +++++++++++++++++++++
>  mm/memory.c             | 22 ++++++++++++++++++++++
>  5 files changed, 130 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/hmm.h b/include/linux/hmm.h
> index 186f497..f243eb5 100644
> --- a/include/linux/hmm.h
> +++ b/include/linux/hmm.h
> @@ -257,6 +257,40 @@ void hmm_mirror_range_dirty(struct hmm_mirror *mirror,
>  			    unsigned long start,
>  			    unsigned long end);
>  
> +int hmm_handle_cpu_fault(struct mm_struct *mm,
> +			struct vm_area_struct *vma,
> +			pmd_t *pmdp, unsigned long addr,
> +			unsigned flags, pte_t orig_pte);
> +
> +int hmm_mm_fork(struct mm_struct *src_mm,
> +		struct mm_struct *dst_mm,
> +		struct vm_area_struct *dst_vma,
> +		pmd_t *dst_pmd,
> +		unsigned long start,
> +		unsigned long end);
> +
> +#else /* CONFIG_HMM */
> +
> +static inline int hmm_handle_mm_fault(struct mm_struct *mm,
I think this should be hmm_handle_cpu_fault, to match the function
declared above in the CONFIG_HMM case.

> +				      struct vm_area_struct *vma,
> +				      pmd_t *pmdp, unsigned long addr,
> +				      unsigned flags, pte_t orig_pte)
> +{
> +	return VM_FAULT_SIGBUS;
> +}
> +
> +static inline int hmm_mm_fork(struct mm_struct *src_mm,
> +			      struct mm_struct *dst_mm,
> +			      struct vm_area_struct *dst_vma,
> +			      pmd_t *dst_pmd,
> +			      unsigned long start,
> +			      unsigned long end)
> +{
> +	BUG();
> +	return -ENOMEM;
> +}
>  
>  #endif /* CONFIG_HMM */
> +
> +
>  #endif

Regards,
Haggai
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