Subject: Re: [PATCH] mm/util.c: Make kvfree() safe for calling while holding
 spinlocks
To:     Manfred Spraul <manfred@colorfullife.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     cgel.zte@gmail.com, shakeelb@google.com, rdunlap@infradead.org,
        dbueso@suse.de, unixbhaskar@gmail.com, chi.minghao@zte.com.cn,
        arnd@arndb.de, Zeal Robot <zealci@zte.com.cn>, linux-mm@kvack.org,
        1vier1@web.de, stable@vger.kernel.org
References: <20211222194828.15320-1-manfred@colorfullife.com>
 <3ca4dec8-f0bd-740f-73c8-34fc6fc1cf66@virtuozzo.com>
 <937f1320-6b7e-9aa2-2a21-7fd2f94eeb32@colorfullife.com>
From:   Vasily Averin <vvs@virtuozzo.com>
Message-ID: <f24d2e3f-1dfd-7bf4-78fa-4eb515b4cd7c@virtuozzo.com>
Date:   Thu, 23 Dec 2021 15:34:26 +0300
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On 23.12.2021 14:52, Manfred Spraul wrote:
> Hello Vasily,
> 
> On 12/23/21 08:21, Vasily Averin wrote:
>>
>> I would prefer to release memory ASAP if it's possible.
>> What do you think about this change?
>> --- a/mm/util.c
>> +++ b/mm/util.c
>> @@ -614,9 +614,12 @@ EXPORT_SYMBOL(kvmalloc_node);
>>    */
>>   void kvfree(const void *addr)
>>   {
>> -       if (is_vmalloc_addr(addr))
>> -               vfree(addr);
>> -       else
>> +       if (is_vmalloc_addr(addr)) {
>> +               if (in_atomic())
>> +                       vfree_atomic();
>> +               else
>> +                       vfree(addr);
>> +       } else
>>                  kfree(addr);
>>   }
>>   EXPORT_SYMBOL(kvfree);
>>
> Unfortunately this cannot work:

yes, you're right and I do not see any better solution yet.