Re: [PATCH 4/6] mm: move flush in madvise_free_pte_range()

Re: [PATCH 4/6] mm: move flush in madvise_free_pte_range()

[Hillf Danton]

> 
> From: Dave Hansen <dave.hansen@linux.intel.com>
> 
> I think this code is OK and does not *need* to be patched.  We
> are just rewriting the PTE without the Accessed and Dirty bits.
> The hardware could come along and set them at any time with or
> without the erratum that this series addresses
> 
> But this does make the ptep_get_and_clear_full() and
> tlb_remove_tlb_entry() calls here more consistent with the other
> places they are used together and look *obviously* the same
> between call-sites.
> 
> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: Minchan Kim <minchan@kernel.org>
> ---
> 
>  b/mm/madvise.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff -puN mm/madvise.c~knl-leak-40-madvise_free_pte_range-move-flush mm/madvise.c
> --- a/mm/madvise.c~knl-leak-40-madvise_free_pte_range-move-flush	2016-06-30 17:10:42.557246755 -0700
> +++ b/mm/madvise.c	2016-06-30 17:10:42.561246936 -0700
> @@ -369,13 +369,13 @@ static int madvise_free_pte_range(pmd_t
>  			 */
>  			ptent = ptep_get_and_clear_full(mm, addr, pte,
>  							tlb->fullmm);
> +			tlb_remove_tlb_entry(tlb, pte, addr);
> 

Then the current comment has to be updated, no?-/

thanks
Hillf
>  			ptent = pte_mkold(ptent);
>  			ptent = pte_mkclean(ptent);
>  			set_pte_at(mm, addr, pte, ptent);
>  			if (PageActive(page))
>  				deactivate_page(page);
> -			tlb_remove_tlb_entry(tlb, pte, addr);
>  		}
>  	}
>  out:
> _
> 


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[PATCH 4/6] mm: move flush in madvise_free_pte_range()

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

I think this code is OK and does not *need* to be patched.  We
are just rewriting the PTE without the Accessed and Dirty bits.
The hardware could come along and set them at any time with or
without the erratum that this series addresses

But this does make the ptep_get_and_clear_full() and
tlb_remove_tlb_entry() calls here more consistent with the other
places they are used together and look *obviously* the same
between call-sites.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Minchan Kim <minchan@kernel.org>
---

 b/mm/madvise.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff -puN mm/madvise.c~knl-leak-40-madvise_free_pte_range-move-flush mm/madvise.c
--- a/mm/madvise.c~knl-leak-40-madvise_free_pte_range-move-flush	2016-06-30 17:10:42.557246755 -0700
+++ b/mm/madvise.c	2016-06-30 17:10:42.561246936 -0700
@@ -369,13 +369,13 @@ static int madvise_free_pte_range(pmd_t
 			 */
 			ptent = ptep_get_and_clear_full(mm, addr, pte,
 							tlb->fullmm);
+			tlb_remove_tlb_entry(tlb, pte, addr);
 
 			ptent = pte_mkold(ptent);
 			ptent = pte_mkclean(ptent);
 			set_pte_at(mm, addr, pte, ptent);
 			if (PageActive(page))
 				deactivate_page(page);
-			tlb_remove_tlb_entry(tlb, pte, addr);
 		}
 	}
 out:
_

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