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Message-ID: <96f13b3c-ec74-4f87-be37-fbf796fe51eb@linux.dev>
Date: Fri, 7 Jun 2024 15:26:46 +0800
From: Chengming Zhou <chengming.zhou@...ux.dev>
To: Vlastimil Babka <vbabka@...e.cz>, Christoph Lameter <cl@...ux.com>,
Pekka Enberg <penberg@...nel.org>, David Rientjes <rientjes@...gle.com>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
Andrew Morton <akpm@...ux-foundation.org>,
Roman Gushchin <roman.gushchin@...ux.dev>,
Hyeonggon Yoo <42.hyeyoo@...il.com>, Feng Tang <feng.tang@...el.com>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
zhouchengming@...edance.com
Subject: Re: [PATCH v2 1/3] slab: make check_object() more consistent
On 2024/6/6 16:28, Vlastimil Babka wrote:
> On 6/5/24 9:13 AM, Chengming Zhou wrote:
>> Now check_object() calls check_bytes_and_report() multiple times to
>> check every section of the object it cares about, like left and right
>> redzones, object poison, paddings poison and freepointer. It will
>> abort the checking process and return 0 once it finds an error.
>>
[...]
>> - /* Check free pointer validity */
>> - if (!check_valid_pointer(s, slab, get_freepointer(s, p))) {
>> + /*
>> + * Cannot check freepointer while object is allocated if
>> + * object and freepointer overlap.
>> + */
>> + if (!freeptr_outside_object(s) && val == SLUB_RED_ACTIVE &&
>
> Seems this condition should have been logically flipped?
Ah, right, will fix.
>
>> + !check_valid_pointer(s, slab, get_freepointer(s, p))) {
>> object_err(s, slab, p, "Freepointer corrupt");
>> /*
>> * No choice but to zap it and thus lose the remainder
>> @@ -1370,9 +1368,14 @@ static int check_object(struct kmem_cache *s, struct slab *slab,
>> * another error because the object count is now wrong.
>> */
>> set_freepointer(s, p, NULL);
>> - return 0;
>
> Should set ret = 0 here?
Yes.
>
>> }
>> - return 1;
>> +
>> + if (!ret && !slab_add_kunit_errors()) {
>
> Also 5/6 of slub_kunit tests now fail as we increased the number of recorded
My bad, I didn't test with slub_kunit, will test later.
> errors vs expected. Either the slab_add_kunit_errors() test above should
> have a variant (parameter?) so it will only detect we are in slab-kunit test
> (to suppress the printing and taint) but doesn't increase slab_errors (we
I think this way is simpler for me, only suppress the printing but doesn't
increase slab_errors, will take this way and test again.
Thanks!
> increased them for the individual issues already), or simply raise the
> expectations of the tests so it matches the new implementation.
>
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