* Re: [PATCH] hugetlbfs: remove meaningless variable avoid_reserve
2021-01-16 9:26 [PATCH] hugetlbfs: remove meaningless variable avoid_reserve Miaohe Lin
@ 2021-01-16 9:39 ` Souptick Joarder
2021-01-18 9:58 ` David Hildenbrand
2021-01-19 18:41 ` Mike Kravetz
2 siblings, 0 replies; 5+ messages in thread
From: Souptick Joarder @ 2021-01-16 9:39 UTC (permalink / raw)
To: Miaohe Lin; +Cc: Mike Kravetz, Linux-MM, linux-kernel
On Sat, Jan 16, 2021 at 2:57 PM Miaohe Lin <linmiaohe@huawei.com> wrote:
>
> The variable avoid_reserve is meaningless because we never changed its
> value and just passed it to alloc_huge_page(). So remove it to make code
> more clear that in hugetlbfs_fallocate, we never avoid reserve when alloc
> hugepage yet.
>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Souptick Joarder <jrdr.linux@gmail.com>
> ---
> fs/hugetlbfs/inode.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
> index 88751e35e69d..23ad6ed8b75f 100644
> --- a/fs/hugetlbfs/inode.c
> +++ b/fs/hugetlbfs/inode.c
> @@ -680,7 +680,6 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
> */
> struct page *page;
> unsigned long addr;
> - int avoid_reserve = 0;
>
> cond_resched();
>
> @@ -717,7 +716,7 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
> }
>
> /* Allocate page and add to page cache */
> - page = alloc_huge_page(&pseudo_vma, addr, avoid_reserve);
> + page = alloc_huge_page(&pseudo_vma, addr, 0);
> hugetlb_drop_vma_policy(&pseudo_vma);
> if (IS_ERR(page)) {
> mutex_unlock(&hugetlb_fault_mutex_table[hash]);
> --
> 2.19.1
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] hugetlbfs: remove meaningless variable avoid_reserve
2021-01-16 9:26 [PATCH] hugetlbfs: remove meaningless variable avoid_reserve Miaohe Lin
2021-01-16 9:39 ` Souptick Joarder
@ 2021-01-18 9:58 ` David Hildenbrand
2021-01-19 18:41 ` Mike Kravetz
2 siblings, 0 replies; 5+ messages in thread
From: David Hildenbrand @ 2021-01-18 9:58 UTC (permalink / raw)
To: Miaohe Lin, mike.kravetz; +Cc: linux-mm, linux-kernel
On 16.01.21 10:26, Miaohe Lin wrote:
> The variable avoid_reserve is meaningless because we never changed its
> value and just passed it to alloc_huge_page(). So remove it to make code
> more clear that in hugetlbfs_fallocate, we never avoid reserve when alloc
> hugepage yet.
>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
> fs/hugetlbfs/inode.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
> index 88751e35e69d..23ad6ed8b75f 100644
> --- a/fs/hugetlbfs/inode.c
> +++ b/fs/hugetlbfs/inode.c
> @@ -680,7 +680,6 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
> */
> struct page *page;
> unsigned long addr;
> - int avoid_reserve = 0;
>
> cond_resched();
>
> @@ -717,7 +716,7 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
> }
>
> /* Allocate page and add to page cache */
> - page = alloc_huge_page(&pseudo_vma, addr, avoid_reserve);
> + page = alloc_huge_page(&pseudo_vma, addr, 0);
> hugetlb_drop_vma_policy(&pseudo_vma);
> if (IS_ERR(page)) {
> mutex_unlock(&hugetlb_fault_mutex_table[hash]);
>
Reviewed-by: David Hildenbrand <david@redhat.com>
--
Thanks,
David / dhildenb
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] hugetlbfs: remove meaningless variable avoid_reserve
2021-01-16 9:26 [PATCH] hugetlbfs: remove meaningless variable avoid_reserve Miaohe Lin
2021-01-16 9:39 ` Souptick Joarder
2021-01-18 9:58 ` David Hildenbrand
@ 2021-01-19 18:41 ` Mike Kravetz
2021-01-20 2:10 ` Miaohe Lin
2 siblings, 1 reply; 5+ messages in thread
From: Mike Kravetz @ 2021-01-19 18:41 UTC (permalink / raw)
To: Miaohe Lin; +Cc: linux-mm, linux-kernel, Andrew Morton
Please CC Andrew on hugetlb patches as they need to go through his tree.
On 1/16/21 1:26 AM, Miaohe Lin wrote:
> The variable avoid_reserve is meaningless because we never changed its
> value and just passed it to alloc_huge_page(). So remove it to make code
> more clear that in hugetlbfs_fallocate, we never avoid reserve when alloc
> hugepage yet.
One might argue that using a named variable makes the call to alloc_huge_page
more clear. I do not disagree with the change, However, there are some
subtle reasons why alloc_huge_page is called with 'avoid_reserve = 0' from
fallocate. Therefore, I would prefer that a comment be added above the call
in addition to this change. See below.
>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
> fs/hugetlbfs/inode.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
> index 88751e35e69d..23ad6ed8b75f 100644
> --- a/fs/hugetlbfs/inode.c
> +++ b/fs/hugetlbfs/inode.c
> @@ -680,7 +680,6 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
> */
> struct page *page;
> unsigned long addr;
> - int avoid_reserve = 0;
>
> cond_resched();
>
> @@ -717,7 +716,7 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
> }
>
> /* Allocate page and add to page cache */
Perhaps, change comment to read:
/*
* Allocate page without setting the avoid_reserve argument.
* There certainly are no reserves associated with the
* pseudo_vma. However, there could be shared mappings with
* reserves for the file at the inode level. If we fallocate
* pages in these areas, we need to consume the reserves
* to keep reservation accounting consistent.
*/
--
Mike Kravetz
> - page = alloc_huge_page(&pseudo_vma, addr, avoid_reserve);
> + page = alloc_huge_page(&pseudo_vma, addr, 0);
> hugetlb_drop_vma_policy(&pseudo_vma);
> if (IS_ERR(page)) {
> mutex_unlock(&hugetlb_fault_mutex_table[hash]);
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] hugetlbfs: remove meaningless variable avoid_reserve
2021-01-19 18:41 ` Mike Kravetz
@ 2021-01-20 2:10 ` Miaohe Lin
0 siblings, 0 replies; 5+ messages in thread
From: Miaohe Lin @ 2021-01-20 2:10 UTC (permalink / raw)
To: Mike Kravetz; +Cc: linux-mm, linux-kernel, Andrew Morton
Hi:
On 2021/1/20 2:41, Mike Kravetz wrote:
> Please CC Andrew on hugetlb patches as they need to go through his tree.
>
> On 1/16/21 1:26 AM, Miaohe Lin wrote:
>> The variable avoid_reserve is meaningless because we never changed its
>> value and just passed it to alloc_huge_page(). So remove it to make code
>> more clear that in hugetlbfs_fallocate, we never avoid reserve when alloc
>> hugepage yet.
>
> One might argue that using a named variable makes the call to alloc_huge_page
> more clear. I do not disagree with the change, However, there are some
> subtle reasons why alloc_huge_page is called with 'avoid_reserve = 0' from
> fallocate. Therefore, I would prefer that a comment be added above the call
> in addition to this change. See below.
>
>>
>> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
>> ---
>> fs/hugetlbfs/inode.c | 3 +--
>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
>> index 88751e35e69d..23ad6ed8b75f 100644
>> --- a/fs/hugetlbfs/inode.c
>> +++ b/fs/hugetlbfs/inode.c
>> @@ -680,7 +680,6 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
>> */
>> struct page *page;
>> unsigned long addr;
>> - int avoid_reserve = 0;
>>
>> cond_resched();
>>
>> @@ -717,7 +716,7 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
>> }
>>
>> /* Allocate page and add to page cache */
>
> Perhaps, change comment to read:
>
> /*
> * Allocate page without setting the avoid_reserve argument.
> * There certainly are no reserves associated with the
> * pseudo_vma. However, there could be shared mappings with
> * reserves for the file at the inode level. If we fallocate
> * pages in these areas, we need to consume the reserves
> * to keep reservation accounting consistent.
> */
>
Many thanks for detailed and excellent comment. Will do it in v2.
Thanks again.
^ permalink raw reply [flat|nested] 5+ messages in thread