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From: Denis Efremov <efremov@linux.com>
To: Julia Lawall <julia.lawall@inria.fr>
Cc: cocci@systeme.lip6.fr, linux-kernel@vger.kernel.org
Subject: Re: [Cocci] [PATCH v6] coccinelle: api: add kvfree script
Date: Mon, 3 Aug 2020 14:33:45 +0300
Message-ID: <a8d8eade-1d98-b8d9-7c66-bd05b22af751@linux.com> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2008022142550.2531@hadrien>



On 8/2/20 11:24 PM, Julia Lawall wrote:
>> +@initialize:python@
>> +@@
>> +# low-level memory api
>> +filter = frozenset(['__vmalloc_area_node'])
>> +
>> +def relevant(p):
>> +    return not (filter & {el.current_element for el in p})
> 
> Is this used?

I'll remove it in v8. Or do you want me to add iterate_dir_item() in the list?

> 
> Otherwise, I think it would be good to not warn about a use of kvfree
> if that use is reachable from a kvmalloc.  There seems to be such a false
> positive in fs/btrfs/send.c, on line 1118.

I don't know how to handle this case without position filter.
It's too complex. In iterate_dir_item() there is:
buf = kmalloc(buf_len, GFP_KERNEL);
while(...) {
	if (...) {
		if (is_vmalloc_addr(buf)) {
			vfree(buf);
			...
		} else {
			char *tmp = krealloc(buf, ...);

			if (!tmp)
				kfree(buf);
			...
		}
		if (!buf) {
			buf = kvmalloc(buf_len, GFP_KERNEL);
			...
		}
	}
}
kvfree(buf);

Adding "when != kvfree(E)" is not enough:
* E = \(kvmalloc\|kvzalloc\|kvcalloc\|kvzalloc_node\|kvmalloc_node\|
*       kvmalloc_array\)(...)@k
	... when != is_vmalloc_addr(E)
+	when != kvfree(E)
	when any
* \(kfree\|kzfree\|vfree\|vfree_atomic\)(E)@p

> 
> It also seems that when there are both a kmalloc and a vmalloc, there is
> no warning if kfree or vfree is used.  Is that intentional?
> 

No, I will try to address it in v8.

Regards,
Denis
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Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-05 20:42 [Cocci] [PATCH] " Denis Efremov
2020-06-05 20:51 ` Julia Lawall
2020-06-05 21:15   ` Denis Efremov
2020-06-05 21:19     ` Julia Lawall
2020-06-14  9:03   ` Denis Efremov
2020-06-14  9:17     ` Julia Lawall
2020-06-14  9:24       ` Denis Efremov
2020-06-14 18:36 ` [Cocci] [PATCH v2] " Denis Efremov
2020-07-17 12:00   ` Denis Efremov
2020-07-30 14:01 ` [Cocci] [PATCH v3] " Denis Efremov
2020-07-30 14:05   ` Denis Efremov
2020-07-30 14:07 ` [Cocci] [PATCH v4] " Denis Efremov
2020-07-30 20:15   ` Julia Lawall
2020-07-30 20:38   ` Julia Lawall
2020-07-31  8:31     ` Denis Efremov
2020-07-31  8:48       ` Julia Lawall
2020-07-31 10:47 ` [Cocci] [PATCH v5] " Denis Efremov
2020-07-31 21:00 ` [Cocci] [PATCH v6] " Denis Efremov
2020-08-02 20:24   ` Julia Lawall
2020-08-03 11:33     ` Denis Efremov [this message]
2020-08-03 12:18       ` Julia Lawall
2020-08-03 11:45   ` Denis Efremov
2020-08-03 12:12     ` Julia Lawall
2020-08-03 18:34 ` [Cocci] [PATCH v7] coccinelle: api: add kfree_mismatch script Denis Efremov
2020-09-21 17:15   ` Denis Efremov
2020-10-15 20:48   ` Julia Lawall
2020-10-16  8:54 ` [Cocci] [PATCH v8] " Denis Efremov
2020-10-17 21:17   ` Julia Lawall
     [not found] <3aea12cf-68dc-e140-936f-cfefb2adbc8f@web.de>
2020-08-02  7:09 ` [Cocci] [PATCH v6] coccinelle: api: add kvfree script Julia Lawall

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