From: Waiman Long <longman@redhat.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>,
Matthew Wilcox <willy@infradead.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
aneesh.kumar@linux.ibm.com, Jarod Wilson <jarod@redhat.com>
Subject: Re: [PATCH v2] mm/hugetlb: defer free_huge_page() to a workqueue
Date: Mon, 16 Dec 2019 13:44:53 -0500 [thread overview]
Message-ID: <21a92649-bb9f-b024-e52b-4ce9355f973b@redhat.com> (raw)
In-Reply-To: <98ac628d-f8be-270d-80bc-bf2373299caf@redhat.com>
On 12/16/19 10:38 AM, Waiman Long wrote:
> On 12/16/19 8:26 AM, Michal Hocko wrote:
>> On Thu 12-12-19 15:52:20, Waiman Long wrote:
>>> On 12/12/19 2:22 PM, Mike Kravetz wrote:
>>>> On 12/12/19 11:04 AM, Davidlohr Bueso wrote:
>>>>> There have been deadlock reports[1, 2] where put_page is called
>>>>> from softirq context and this causes trouble with the hugetlb_lock,
>>>>> as well as potentially the subpool lock.
>>>>>
>>>>> For such an unlikely scenario, lets not add irq dancing overhead
>>>>> to the lock+unlock operations, which could incur in expensive
>>>>> instruction dependencies, particularly when considering hard-irq
>>>>> safety. For example PUSHF+POPF on x86.
>>>>>
>>>>> Instead, just use a workqueue and do the free_huge_page() in regular
>>>>> task context.
>>>>>
>>>>> [1] https://lore.kernel.org/lkml/20191211194615.18502-1-longman@redhat.com/
>>>>> [2] https://lore.kernel.org/lkml/20180905112341.21355-1-aneesh.kumar@linux.ibm.com/
>>>>>
>>>>> Reported-by: Waiman Long <longman@redhat.com>
>>>>> Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
>>>>> Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
>>>> Thank you Davidlohr.
>>>>
>>>> The patch does seem fairly simple and straight forward. I need to brush up
>>>> on my workqueue knowledge to provide a full review.
>>>>
>>>> Longman,
>>>> Do you have a test to reproduce the issue? If so, can you try running with
>>>> this patch.
>>> Yes, I do have a test that can reproduce the issue. I will run it with
>>> the patch and report the status tomorrow.
>> Can you extract guts of the testcase and integrate them into hugetlb
>> test suite?
BTW, what hugetlb test suite are you talking about?
Cheers,
Longman
next prev parent reply other threads:[~2019-12-16 18:45 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-11 19:46 [PATCH v2] hugetlbfs: Disable softIRQ when taking hugetlb_lock Waiman Long
2019-12-11 22:04 ` Mike Kravetz
2019-12-11 22:19 ` Waiman Long
2019-12-12 1:11 ` Mike Kravetz
2019-12-12 6:06 ` Davidlohr Bueso
2019-12-12 6:30 ` Davidlohr Bueso
2019-12-12 19:04 ` [PATCH v2] mm/hugetlb: defer free_huge_page() to a workqueue Davidlohr Bueso
2019-12-12 19:22 ` Mike Kravetz
2019-12-12 19:36 ` Davidlohr Bueso
2019-12-12 20:52 ` Waiman Long
2019-12-12 21:04 ` Waiman Long
2019-12-16 13:26 ` Michal Hocko
2019-12-16 15:38 ` Waiman Long
2019-12-16 18:44 ` Waiman Long [this message]
2019-12-17 9:00 ` Michal Hocko
2019-12-17 18:05 ` Mike Kravetz
2019-12-18 12:18 ` hugetlbfs testing coverage (was: Re: [PATCH v2] mm/hugetlb: defer free_huge_page() to a workqueue) Michal Hocko
2019-12-12 21:01 ` [PATCH v2] mm/hugetlb: defer free_huge_page() to a workqueue Waiman Long
2019-12-16 13:37 ` Michal Hocko
2019-12-16 16:17 ` Waiman Long
2019-12-16 16:17 ` Davidlohr Bueso
2019-12-16 17:18 ` Matthew Wilcox
2019-12-16 19:08 ` Mike Kravetz
2019-12-16 19:13 ` Waiman Long
2019-12-12 21:32 ` [PATCH v2] hugetlbfs: Disable softIRQ when taking hugetlb_lock Andi Kleen
2019-12-12 22:42 ` Davidlohr Bueso
2019-12-11 23:05 ` Andi Kleen
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