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Subject: Re: [RFC PATCH 7/8] hugetlb: add update_and_free_page_no_sleep for
 irq context
To:     Hillf Danton <hdanton@sina.com>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org
References: <20210319224209.150047-1-mike.kravetz@oracle.com>
 <20210320011857.2004-1-hdanton@sina.com>
From:   Mike Kravetz <mike.kravetz@oracle.com>
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Date:   Wed, 24 Mar 2021 17:26:58 -0700
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On 3/19/21 6:18 PM, Hillf Danton wrote:
> On Fri, 19 Mar 2021 15:42:08 -0700  Mike Kravetz wrote:
>> +
>> +	if (!can_sleep && free_page_may_sleep(h, page)) {
>> +		/*
>> +		 * Send page freeing to workqueue
>> +		 *
>> +		 * Only call schedule_work() if hpage_freelist is previously
>> +		 * empty. Otherwise, schedule_work() had been called but the
>> +		 * workfn hasn't retrieved the list yet.
>> +		 */
>> +		if (llist_add((struct llist_node *)&page->mapping,
>> +					&hpage_freelist))
>> +			schedule_work(&free_hpage_work);
>> +		return;
>> +	}
> 
> Queue work on system_unbound_wq instead of system_wq because of blocking work.
> 

Thanks Hillf,

I am dropping this patch and going with Roman's patches to create an
version of cma_release that will not sleep.  A workqueue handoff like
this may be needed in the vmemmap reduction series, so will keep this in
mind.
-- 
Mike Kravetz