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SubjectRe: [PATCH -mmotm-2010-01-06-14-34] Count minor fault in break_ksm
On Mon, 11 Jan 2010, Minchan Kim wrote:

> We have counted task's maj/min fault after handle_mm_fault.
> break_ksm misses that.
>
> I wanted to check by VM_FAULT_ERROR.
> But now break_ksm doesn't handle HWPOISON error.

Sorry, no, I just don't see a good reason to add this.
Imagine it this way: these aren't really faults, KSM simply
happens to be using "handle_mm_fault" to achieve what it needs.

(And, of course, if we did add something like this, I'd be
disagreeing with you about which tsk's min_flt to increment.)

Hugh

>
> Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
> CC: Hugh Dickins <hugh.dickins@tiscali.co.uk>
> CC: Izik Eidus <ieidus@redhat.com>
> ---
> mm/ksm.c | 6 +++++-
> 1 files changed, 5 insertions(+), 1 deletions(-)
>
> diff --git a/mm/ksm.c b/mm/ksm.c
> index 56a0da1..3a1fda4 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -367,9 +367,13 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr)
> page = follow_page(vma, addr, FOLL_GET);
> if (!page)
> break;
> - if (PageKsm(page))
> + if (PageKsm(page)) {
> ret = handle_mm_fault(vma->vm_mm, vma, addr,
> FAULT_FLAG_WRITE);
> + if (!(ret & (VM_FAULT_SIGBUS | VM_FAULT_OOM)
> + || current->flags & PF_KTHREAD))
> + current->min_flt++;
> + }
> else
> ret = VM_FAULT_WRITE;
> put_page(page);
> --
> 1.5.6.3
>
>
>
> --
> Kind regards,
> Minchan Kim


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