From: Waiman Long <longman@redhat.com>
To: 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,
Michal Hocko <mhocko@kernel.org>,
aneesh.kumar@linux.ibm.com
Subject: Re: [PATCH v2] mm/hugetlb: defer free_huge_page() to a workqueue
Date: Thu, 12 Dec 2019 16:04:29 -0500 [thread overview]
Message-ID: <3bdddd47-c93e-6549-d36f-8eb8e8d9be12@redhat.com> (raw)
In-Reply-To: <79d3a7e1-384b-b759-cd84-56253fb9ed40@redhat.com>
On 12/12/19 3:52 PM, 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.
I don't think Davidlohr's patch is ready for prime time yet. So I will
wait until a better version is available.
Cheers,
Longman
next prev parent reply other threads:[~2019-12-12 21:04 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 [this message]
2019-12-16 13:26 ` Michal Hocko
2019-12-16 15:38 ` Waiman Long
2019-12-16 18:44 ` Waiman Long
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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