Re: [PATCH 6.6.y] selftests/bpf: Remove flaky test_btf_id test

[Greg KH <greg@kroah.com>]

On Thu, Feb 01, 2024 at 07:45:45PM -0800, Samasth Norway Ananda wrote:
> From: Yonghong Song <yonghong.song@linux.dev>
> 
> [ Upstream commit 56925f389e152dcb8d093435d43b78a310539c23 ]
> 
> With previous patch, one of subtests in test_btf_id becomes
> flaky and may fail. The following is a failing example:
> 
>   Error: #26 btf
>   Error: #26/174 btf/BTF ID
>     Error: #26/174 btf/BTF ID
>     btf_raw_create:PASS:check 0 nsec
>     btf_raw_create:PASS:check 0 nsec
>     test_btf_id:PASS:check 0 nsec
>     ...
>     test_btf_id:PASS:check 0 nsec
>     test_btf_id:FAIL:check BTF lingersdo_test_get_info:FAIL:check failed: -1
> 
> The test tries to prove a btf_id not available after the map is closed.
> But btf_id is freed only after workqueue and a rcu grace period, compared
> to previous case just after a rcu grade period.
> Depending on system workload, workqueue could take quite some time
> to execute function bpf_map_free_deferred() which may cause the test failure.
> Instead of adding arbitrary delays, let us remove the logic to
> check btf_id availability after map is closed.
> 
> Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
> Link: https://lore.kernel.org/r/20231214203820.1469402-1-yonghong.song@linux.dev
> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
> [Samasth: backport for 6.6.y]
> Signed-off-by: Samasth Norway Ananda <samasth.norway.ananda@oracle.com>
> ---
> Above patch is a fix for 59e5791f59dd ("bpf: Fix a race condition between 
> btf_put() and map_free()"). While the commit causing the error is
> present in 6.6.y the fix is not present. 
> ---
>  tools/testing/selftests/bpf/prog_tests/btf.c | 5 -----
>  1 file changed, 5 deletions(-)

What about 6.7 as well?  Shouldn't this change be there too?

thanks,

greg k-h