From: Mike Kravetz <mike.kravetz@oracle.com>
To: Miaohe Lin <linmiaohe@huawei.com>, akpm@linux-foundation.org
Cc: n-horiguchi@ah.jp.nec.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH 3/4] mm/hugeltb: fix potential wrong gbl_reserve value for hugetlb_acct_memory()
Date: Thu, 8 Apr 2021 21:37:46 -0700 [thread overview]
Message-ID: <83e5f2a0-bf92-ab42-c5ff-52a07eab9ee8@oracle.com> (raw)
In-Reply-To: <8dfe32a3-1789-6a40-b650-304c2cfb6531@huawei.com>
On 4/8/21 8:01 PM, Miaohe Lin wrote:
> On 2021/4/9 6:53, Mike Kravetz wrote:
>>
>> Yes, add a comment to hugetlb_unreserve_pages saying that !resv_map
>> implies freed == 0.
>>
>
> Sounds good!
>
>> It would also be helpful to check for (chg - freed) == 0 and skip the
>> calls to hugepage_subpool_put_pages() and hugetlb_acct_memory(). Both
>> of those routines may perform an unnecessary lock/unlock cycle in this
>> case.
>>
>> A simple
>> if (chg == free)
>> return 0;
>> before the call to hugepage_subpool_put_pages would work.
>
> This may not be really helpful because hugepage_subpool_put_pages() and hugetlb_acct_memory()
> both would handle delta == 0 case without unnecessary lock/unlock cycle.
> Does this make sense for you? If so, I will prepare v2 with the changes to add a comment
> to hugetlb_unreserve_pages() __without__ the check for (chg - freed) == 0.
Sorry, I forgot about the recent changes to check for delta == 0.
No need for the check here, just the comment.
--
Mike Kravetz
next prev parent reply other threads:[~2021-04-09 4:38 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-02 9:32 [PATCH 0/4] Cleanup and fixup for hugetlb Miaohe Lin
2021-04-02 9:32 ` [PATCH 1/4] mm/hugeltb: remove redundant VM_BUG_ON() in region_add() Miaohe Lin
2021-04-07 0:16 ` Mike Kravetz
2021-04-02 9:32 ` [PATCH 2/4] mm/hugeltb: simplify the return code of __vma_reservation_common() Miaohe Lin
2021-04-07 0:53 ` Mike Kravetz
2021-04-07 2:05 ` Miaohe Lin
2021-04-07 2:37 ` Mike Kravetz
2021-04-07 3:09 ` Miaohe Lin
2021-04-07 21:23 ` Mike Kravetz
2021-04-08 2:44 ` Miaohe Lin
2021-04-08 22:40 ` Mike Kravetz
2021-04-09 2:52 ` Miaohe Lin
2021-04-02 9:32 ` [PATCH 3/4] mm/hugeltb: fix potential wrong gbl_reserve value for hugetlb_acct_memory() Miaohe Lin
2021-04-07 2:49 ` Mike Kravetz
2021-04-07 7:24 ` Miaohe Lin
2021-04-07 20:53 ` Mike Kravetz
2021-04-08 3:24 ` Miaohe Lin
2021-04-08 3:26 ` Miaohe Lin
2021-04-08 22:53 ` Mike Kravetz
2021-04-09 3:01 ` Miaohe Lin
2021-04-09 4:37 ` Mike Kravetz [this message]
2021-04-09 6:36 ` Miaohe Lin
2021-04-02 9:32 ` [PATCH 4/4] mm/hugeltb: handle the error case in hugetlb_fix_reserve_counts() Miaohe Lin
2021-04-08 23:25 ` Mike Kravetz
2021-04-09 3:17 ` Miaohe Lin
2021-04-09 5:04 ` Andrew Morton
2021-04-09 7:07 ` Miaohe Lin
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