Re: Patch "mm: migration: do not lose soft dirty bit if page is in migration state" has been added to the 3.4-stable tree

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On Wed, Oct 30, 2013 at 02:19:33PM -0700, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
> 
> This is a note to let you know that I've just added the patch titled
> 
>     mm: migration: do not lose soft dirty bit if page is in migration state
> 
> to the 3.4-stable tree which can be found at:
>     http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

Nope, it breaks the build so I have to remove this.

If it's needed in 3.4, can someone provide a backported version that
works?

thanks,

greg k-h



> 
> The filename of the patch is:
>      mm-migration-do-not-lose-soft-dirty-bit-if-page-is-in-migration-state.patch
> and it can be found in the queue-3.4 subdirectory.
> 
> If you, or anyone else, feels it should not be added to the stable tree,
> please let <stable@xxxxxxxxxxxxxxx> know about it.
> 
> 
> >From c3d16e16522fe3fe8759735850a0676da18f4b1d Mon Sep 17 00:00:00 2001
> From: Cyrill Gorcunov <gorcunov@xxxxxxxxx>
> Date: Wed, 16 Oct 2013 13:46:51 -0700
> Subject: mm: migration: do not lose soft dirty bit if page is in migration state
> 
> From: Cyrill Gorcunov <gorcunov@xxxxxxxxx>
> 
> commit c3d16e16522fe3fe8759735850a0676da18f4b1d upstream.
> 
> If page migration is turned on in config and the page is migrating, we
> may lose the soft dirty bit.  If fork and mprotect are called on
> migrating pages (once migration is complete) pages do not obtain the
> soft dirty bit in the correspond pte entries.  Fix it adding an
> appropriate test on swap entries.
> 
> Signed-off-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
> Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
> Cc: Matt Mackall <mpm@xxxxxxxxxxx>
> Cc: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx>
> Cc: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
> Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxx>
> Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
> Cc: Mel Gorman <mel@xxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> 
> ---
>  mm/memory.c   |    2 ++
>  mm/migrate.c  |    2 ++
>  mm/mprotect.c |    7 +++++--
>  3 files changed, 9 insertions(+), 2 deletions(-)
> 
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -876,6 +876,8 @@ copy_one_pte(struct mm_struct *dst_mm, s
>  					 */
>  					make_migration_entry_read(&entry);
>  					pte = swp_entry_to_pte(entry);
> +					if (pte_swp_soft_dirty(*src_pte))
> +						pte = pte_swp_mksoft_dirty(pte);
>  					set_pte_at(src_mm, addr, src_pte, pte);
>  				}
>  			}
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -139,6 +139,8 @@ static int remove_migration_pte(struct p
>  
>  	get_page(new);
>  	pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
> +	if (pte_swp_soft_dirty(*ptep))
> +		pte = pte_mksoft_dirty(pte);
>  	if (is_write_migration_entry(entry))
>  		pte = pte_mkwrite(pte);
>  #ifdef CONFIG_HUGETLB_PAGE
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -64,13 +64,16 @@ static void change_pte_range(struct mm_s
>  			swp_entry_t entry = pte_to_swp_entry(oldpte);
>  
>  			if (is_write_migration_entry(entry)) {
> +				pte_t newpte;
>  				/*
>  				 * A protection check is difficult so
>  				 * just be safe and disable write
>  				 */
>  				make_migration_entry_read(&entry);
> -				set_pte_at(mm, addr, pte,
> -					swp_entry_to_pte(entry));
> +				newpte = swp_entry_to_pte(entry);
> +				if (pte_swp_soft_dirty(oldpte))
> +					newpte = pte_swp_mksoft_dirty(newpte);
> +				set_pte_at(mm, addr, pte, newpte);
>  			}
>  		}
>  	} while (pte++, addr += PAGE_SIZE, addr != end);
> 
> 
> Patches currently in stable-queue which might be from gorcunov@xxxxxxxxx are
> 
> queue-3.4/mm-migration-do-not-lose-soft-dirty-bit-if-page-is-in-migration-state.patch
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