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Date: Mon, 16 Sep 2019 15:25:57 -0700
From: Mike Kravetz <mike.kravetz@...cle.com>
To: Mina Almasry <almasrymina@...gle.com>
Cc: shuah@...nel.org, rientjes@...gle.com, shakeelb@...gle.com,
gthelen@...gle.com, akpm@...ux-foundation.org,
khalid.aziz@...cle.com, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, linux-kselftest@...r.kernel.org,
cgroups@...r.kernel.org, aneesh.kumar@...ux.vnet.ibm.com,
mkoutny@...e.com
Subject: Re: [PATCH v4 5/9] hugetlb: remove duplicated code
On 9/10/19 4:31 PM, Mina Almasry wrote:
> Remove duplicated code between region_chg and region_add, and refactor it into
> a common function, add_reservation_in_range. This is mostly done because
> there is a follow up change in this series that disables region
> coalescing in region_add, and I want to make that change in one place
> only. It should improve maintainability anyway on its own.
>
> Signed-off-by: Mina Almasry <almasrymina@...gle.com>
Like the previous patch, this is a good improvement indepentent of the
rest of the series. Thanks!
Reviewed-by: Mike Kravetz <mike.kravetz@...cle.com>
--
Mike Kravetz
> ---
> mm/hugetlb.c | 116 ++++++++++++++++++++++++---------------------------
> 1 file changed, 54 insertions(+), 62 deletions(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index bea51ae422f63..ce5ed1056fefd 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -244,6 +244,57 @@ struct file_region {
> long to;
> };
>
> +static long add_reservation_in_range(
> + struct resv_map *resv, long f, long t, bool count_only)
> +{
> +
> + long chg = 0;
> + struct list_head *head = &resv->regions;
> + struct file_region *rg = NULL, *trg = NULL, *nrg = NULL;
> +
> + /* Locate the region we are before or in. */
> + list_for_each_entry(rg, head, link)
> + if (f <= rg->to)
> + break;
> +
> + /* Round our left edge to the current segment if it encloses us. */
> + if (f > rg->from)
> + f = rg->from;
> +
> + chg = t - f;
> +
> + /* Check for and consume any regions we now overlap with. */
> + nrg = rg;
> + list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
> + if (&rg->link == head)
> + break;
> + if (rg->from > t)
> + break;
> +
> + /* We overlap with this area, if it extends further than
> + * us then we must extend ourselves. Account for its
> + * existing reservation.
> + */
> + if (rg->to > t) {
> + chg += rg->to - t;
> + t = rg->to;
> + }
> + chg -= rg->to - rg->from;
> +
> + if (!count_only && rg != nrg) {
> + list_del(&rg->link);
> + kfree(rg);
> + }
> + }
> +
> + if (!count_only) {
> + nrg->from = f;
> + nrg->to = t;
> + }
> +
> + return chg;
> +}
> +
> /*
> * Add the huge page range represented by [f, t) to the reserve
> * map. Existing regions will be expanded to accommodate the specified
> @@ -257,7 +308,7 @@ struct file_region {
> static long region_add(struct resv_map *resv, long f, long t)
> {
> struct list_head *head = &resv->regions;
> - struct file_region *rg, *nrg, *trg;
> + struct file_region *rg, *nrg;
> long add = 0;
>
> spin_lock(&resv->lock);
> @@ -287,38 +338,7 @@ static long region_add(struct resv_map *resv, long f, long t)
> goto out_locked;
> }
>
> - /* Round our left edge to the current segment if it encloses us. */
> - if (f > rg->from)
> - f = rg->from;
> -
> - /* Check for and consume any regions we now overlap with. */
> - nrg = rg;
> - list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
> - if (&rg->link == head)
> - break;
> - if (rg->from > t)
> - break;
> -
> - /* If this area reaches higher then extend our area to
> - * include it completely. If this is not the first area
> - * which we intend to reuse, free it. */
> - if (rg->to > t)
> - t = rg->to;
> - if (rg != nrg) {
> - /* Decrement return value by the deleted range.
> - * Another range will span this area so that by
> - * end of routine add will be >= zero
> - */
> - add -= (rg->to - rg->from);
> - list_del(&rg->link);
> - kfree(rg);
> - }
> - }
> -
> - add += (nrg->from - f); /* Added to beginning of region */
> - nrg->from = f;
> - add += t - nrg->to; /* Added to end of region */
> - nrg->to = t;
> + add = add_reservation_in_range(resv, f, t, false);
>
> out_locked:
> resv->adds_in_progress--;
> @@ -345,8 +365,6 @@ static long region_add(struct resv_map *resv, long f, long t)
> */
> static long region_chg(struct resv_map *resv, long f, long t)
> {
> - struct list_head *head = &resv->regions;
> - struct file_region *rg;
> long chg = 0;
>
> spin_lock(&resv->lock);
> @@ -375,34 +393,8 @@ static long region_chg(struct resv_map *resv, long f, long t)
> goto retry_locked;
> }
>
> - /* Locate the region we are before or in. */
> - list_for_each_entry(rg, head, link)
> - if (f <= rg->to)
> - break;
> -
> - /* Round our left edge to the current segment if it encloses us. */
> - if (f > rg->from)
> - f = rg->from;
> - chg = t - f;
> -
> - /* Check for and consume any regions we now overlap with. */
> - list_for_each_entry(rg, rg->link.prev, link) {
> - if (&rg->link == head)
> - break;
> - if (rg->from > t)
> - goto out;
> + chg = add_reservation_in_range(resv, f, t, true);
>
> - /* We overlap with this area, if it extends further than
> - * us then we must extend ourselves. Account for its
> - * existing reservation. */
> - if (rg->to > t) {
> - chg += rg->to - t;
> - t = rg->to;
> - }
> - chg -= rg->to - rg->from;
> - }
> -
> -out:
> spin_unlock(&resv->lock);
> return chg;
> }
> --
> 2.23.0.162.g0b9fbb3734-goog
>
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