Subject: Re: [PATCH 1/4] mm/vmalloc: allow to call vfree() in atomic context
To: Michal Hocko <mhocko@kernel.org>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>
References: <20170330102719.13119-1-aryabinin@virtuozzo.com>
 <2cfc601e-3093-143e-b93d-402f330a748a@vmware.com>
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 <20170404094148.GJ15132@dhcp22.suse.cz>
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        <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>, <hpa@zytor.com>,
        <chris@chris-wilson.co.uk>, <hch@lst.de>, <mingo@elte.hu>,
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From: Thomas Hellstrom <thellstrom@vmware.com>
Message-ID: <2b95af00-e4e6-4df7-7cd5-30b4f6980b09@vmware.com>
Date: Tue, 4 Apr 2017 11:49:03 +0200
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On 04/04/2017 11:41 AM, Michal Hocko wrote:
> On Thu 30-03-17 17:48:39, Andrey Ryabinin wrote:
>> From: Andrey Ryabinin <aryabinin@virtuozzo.com>
>> Subject: mm/vmalloc: allow to call vfree() in atomic context fix
>>
>> Don't spawn worker if we already purging.
>>
>> Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
> I would rather put this into a separate patch. Ideally with some numners
> as this is an optimization...

Actually, this just mimics what the code was doing before, as it only
invoked
__purge_vmap_area_lazy() if the trylock succeeded.

/Thomas


>
>> ---
>>  mm/vmalloc.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
>> index ea1b4ab..88168b8 100644
>> --- a/mm/vmalloc.c
>> +++ b/mm/vmalloc.c
>> @@ -737,7 +737,8 @@ static void free_vmap_area_noflush(struct vmap_area *va)
>>  	/* After this point, we may free va at any time */
>>  	llist_add(&va->purge_list, &vmap_purge_list);
>>  
>> -	if (unlikely(nr_lazy > lazy_max_pages()))
>> +	if (unlikely(nr_lazy > lazy_max_pages()) &&
>> +	    !mutex_is_locked(&vmap_purge_lock))
>>  		schedule_work(&purge_vmap_work);
>>  }
>>  
>> -- 
>> 2.10.2
>>