linux-kernel - Re: [PATCH V2 1/4] hugetlbfs: add minimum size tracking fields to subpool structure

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Message-Id: <20150318142558.d2958fbb7f8b083c00c40c0d@linux-foundation.org>
Date:	Wed, 18 Mar 2015 14:25:58 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Mike Kravetz <mike.kravetz@...cle.com>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Davidlohr Bueso <dave@...olabs.net>,
	Aneesh Kumar <aneesh.kumar@...ux.vnet.ibm.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH V2 1/4] hugetlbfs: add minimum size tracking fields to
 subpool structure

On Mon, 16 Mar 2015 16:53:26 -0700 Mike Kravetz <mike.kravetz@...cle.com> wrote:

> Add a field to the subpool structure to indicate the minimimum
> number of huge pages to always be used by this subpool.  This
> minimum count includes allocated pages as well as reserved pages.
> If the minimum number of pages for the subpool have not been
> allocated, pages are reserved up to this minimum.  An additional
> field (rsv_hpages) is used to track the number of pages reserved
> to meet this minimum size.  The hstate pointer in the subpool
> is convenient to have when reserving and unreserving the pages.
> 
> ...
>
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -23,6 +23,8 @@ struct hugepage_subpool {
>  	spinlock_t lock;
>  	long count;
>  	long max_hpages, used_hpages;
> +	struct hstate *hstate;
> +	long min_hpages, rsv_hpages;
>  };

Let's leave room for the descriptive comments which aren't there.

--- a/include/linux/hugetlb.h~hugetlbfs-add-minimum-size-tracking-fields-to-subpool-structure-fix
+++ a/include/linux/hugetlb.h
@@ -22,9 +22,11 @@ struct mmu_gather;
 struct hugepage_subpool {
 	spinlock_t lock;
 	long count;
-	long max_hpages, used_hpages;
+	long max_hpagesl
+	long used_hpages;
 	struct hstate *hstate;
-	long min_hpages, rsv_hpages;
+	long min_hpages;
+	long rsv_hpages;
 };
 
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -85,6 +85,9 @@ struct hugepage_subpool *hugepage_new_subpool(long nr_blocks)
>  	spool->count = 1;
>  	spool->max_hpages = nr_blocks;
>  	spool->used_hpages = 0;
> +	spool->hstate = NULL;
> +	spool->min_hpages = 0;
> +	spool->rsv_hpages = 0;

Four strikes and you're out!

--- a/mm/hugetlb.c~hugetlbfs-add-minimum-size-tracking-fields-to-subpool-structure-fix
+++ a/mm/hugetlb.c
@@ -77,17 +77,13 @@ struct hugepage_subpool *hugepage_new_su
 {
 	struct hugepage_subpool *spool;
 
-	spool = kmalloc(sizeof(*spool), GFP_KERNEL);
+	spool = kzalloc(sizeof(*spool), GFP_KERNEL);
 	if (!spool)
 		return NULL;
 
 	spin_lock_init(&spool->lock);
 	spool->count = 1;
 	spool->max_hpages = nr_blocks;
-	spool->used_hpages = 0;
-	spool->hstate = NULL;
-	spool->min_hpages = 0;
-	spool->rsv_hpages = 0;
 
 	return spool;
 }
_

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