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From: Mike Kravetz <mike.kravetz@oracle.com>
To: Andrew Morton <akpm@linux-foundation.org>,
	Waiman Long <longman@redhat.com>,
	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 11:22:55 -0800	[thread overview]
Message-ID: <d6b9743c-776c-d740-73af-a600f15b910a@oracle.com> (raw)
In-Reply-To: <20191212190427.ouyohviijf5inhur@linux-p48b>

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.
-- 
Mike Kravetz

  reply	other threads:[~2019-12-12 19:23 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 [this message]
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
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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