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SubjectRe: [PATCH v2 2/2] x86, range: Do not add new blank slot with add_range_with_merge
Hi,

On 10 June 2013 09:29, Yinghai Lu <yinghai@kernel.org> wrote:
> Joshua reported: Commit cd7b304dfaf1 (x86, range: fix missing merge
> during add range) broke mtrr cleanup on his setup in 3.9.5.
> corresponding commit in upstream is fbe06b7bae7c.
>
> The reason is add_range_with_merge could generate blank spot.
>
> We could avoid that by searching new expanded start/end, that
> new range should include all connected ranges in range array.
> At last add the new expanded start/end to the range array.
> Also move up left array so do not add new blank slot in the
> range array.
>
> -v2: move left array to avoid enhance add_range()
>
> Reported-by: Joshua Covington <joshuacov@googlemail.com>
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> Cc: <stable@vger.kernel.org> v3.9
>
> ---
> arch/x86/kernel/cpu/mtrr/cleanup.c | 2 +-
> kernel/range.c | 21 +++++++++++----------
> 2 files changed, 12 insertions(+), 11 deletions(-)
>
> Index: linux-2.6/kernel/range.c
> ===================================================================
> --- linux-2.6.orig/kernel/range.c
> +++ linux-2.6/kernel/range.c
> @@ -32,9 +32,8 @@ int add_range_with_merge(struct range *r
> if (start >= end)
> return nr_range;
>
> - /* Try to merge it with old one: */
> + /* get new start/end: */
> for (i = 0; i < nr_range; i++) {
> - u64 final_start, final_end;
> u64 common_start, common_end;
>
> if (!range[i].end)
> @@ -45,14 +44,16 @@ int add_range_with_merge(struct range *r
> if (common_start > common_end)
> continue;
>
> - final_start = min(range[i].start, start);
> - final_end = max(range[i].end, end);
> -
> - /* clear it and add it back for further merge */
> - range[i].start = 0;
> - range[i].end = 0;
> - return add_range_with_merge(range, az, nr_range,
> - final_start, final_end);
> + /* new start/end, will add it back at last */
> + start = min(range[i].start, start);
> + end = max(range[i].end, end);
> +
> + memmove(&range[i], &range[i + 1],
> + (nr_range - (i + 1)) * sizeof(range[i]));
> + range[nr_range - 1].start = 0;
> + range[nr_range - 1].end = 0;
> + nr_range--;
> + i--;
> }
>
> /* Need to add it: */
> --
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patches 1,2(latest one) have not helped me on 3.9.5:

rathamahata@piledriver /usr/local/src/linux-3.9.5 $ cat /proc/cmdline
BOOT_IMAGE=/boot/linux-3.9.5 root=/dev/sda1 rootflags=commit=9
elevator=cfq enable_mtrr_cleanup mtrr_spare_reg_nr=1
rathamahata@piledriver /usr/local/src/linux-3.9.5 $ cat /proc/mtrr
reg00: base=0x000000000 ( 0MB), size= 2048MB, count=1: write-back
reg01: base=0x080000000 ( 2048MB), size= 256MB, count=1: write-back
reg02: base=0x08f800000 ( 2296MB), size= 8MB, count=1: uncachable
reg03: base=0x0b0000000 ( 2816MB), size= 256MB, count=1: write-combining
reg04: base=0x0c0000000 ( 3072MB), size= 256MB, count=1: write-combining
rathamahata@piledriver /usr/local/src/linux-3.9.5 $ free -m
total used free shared buffers cached
Mem: 7370 714 6656 0 35 243
-/+ buffers/cache: 434 6935
Swap: 3659 0 3659
rathamahata@piledriver /usr/local/src/linux-3.9.5 $


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