Re: [PATCH RESEND] bpf: fix order of args in call to bpf_map_kvcalloc

[Linux regression tracking (Thorsten Leemhuis)]

[CCing the regressions list and people mentioned below]

On 12.06.24 16:53, Alexei Starovoitov wrote:
> On Wed, Jun 12, 2024 at 2:51 AM Mohammad Shehar Yaar Tausif
> <sheharyaar48@xxxxxxxxx> wrote:
>>
>> The original function call passed size of smap->bucket before the number of
>> buckets which raises the error 'calloc-transposed-args' on compilation.
>>
>> Fixes: 62827d612ae5 ("bpf: Remove __bpf_local_storage_map_alloc")
>> Reviewed-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
>> Signed-off-by: Mohammad Shehar Yaar Tausif <sheharyaar48@xxxxxxxxx>
>> ---
>> - already merged in linux-next
>> - [1] suggested sending as a fix for 6.10 cycle
> 
> No. It's not a fix.

If you have a minute, could you please explain why that is? From what I
can see a quite a few people run into build problems with 6.10-rc
recently that are fixed by the patch:

* Péter Ujfalusi
https://lore.kernel.org/bpf/363ad8d1-a2d2-4fca-b66a-3d838eb5def9@xxxxxxxxx/

* Christian Kujau
https://lore.kernel.org/bpf/48360912-b239-51f2-8f25-07a46516dc76@xxxxxxxxxxxxxxx/
https://lore.kernel.org/lkml/d0dd2457-ab58-1b08-caa4-93eaa2de221e@xxxxxxxxxxxxxxx/

* Lorenzo Stoakes
https://fosstodon.org/@ljs@xxxxxxxxxxxxxxxxx/112734050799590482

At the same time I see that the culprit mentioned above is from 6.4-rc1,
so I guess it there must be some other reason why a few people seem to
tun into this now. Did some other change expose this problem? Or are
updated compilers causing this?

Ciao, Thorsten

>> [1] https://lore.kernel.org/all/363ad8d1-a2d2-4fca-b66a-3d838eb5def9@xxxxxxxxx/
>> ---
>>  kernel/bpf/bpf_local_storage.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c
>> index 976cb258a0ed..c938dea5ddbf 100644
>> --- a/kernel/bpf/bpf_local_storage.c
>> +++ b/kernel/bpf/bpf_local_storage.c
>> @@ -782,8 +782,8 @@ bpf_local_storage_map_alloc(union bpf_attr *attr,
>>         nbuckets = max_t(u32, 2, nbuckets);
>>         smap->bucket_log = ilog2(nbuckets);
>>
>> -       smap->buckets = bpf_map_kvcalloc(&smap->map, sizeof(*smap->buckets),
>> -                                        nbuckets, GFP_USER | __GFP_NOWARN);
>> +       smap->buckets = bpf_map_kvcalloc(&smap->map, nbuckets,
>> +                                        sizeof(*smap->buckets), GFP_USER | __GFP_NOWARN);
>>         if (!smap->buckets) {
>>                 err = -ENOMEM;
>>                 goto free_smap;
>>
>> ---
>> base-commit: 2ef5971ff345d3c000873725db555085e0131961
>> change-id: 20240612-master-fe9e63ab5c95
>>
>> Best regards,
>> --
>> Mohammad Shehar Yaar Tausif <sheharyaar48@xxxxxxxxx>
>>