Hi Zi,
On <Date of Zi's email>, Zi Yan wrote:
On 9 Jul 2025, at 8:32, wang lian wrote:
Hi Zi Yan, Thanks for testing the patch and reporting this build failure. I don't have an arm64 environment readily available for testing, so I appreciate you catching this. I suspect this is caused by missing or older userspace headers in the cross-compilation toolchain.
Right. My /usr/include/sys does not have pidfd.h. IMHO selftests should not rely on userspace headers, otherwise we cannot test latest kernel changes.
I will try to fix this in the next version. If the problem persists, a good solution would be to manually define the syscall wrapper to avoid the dependency on <sys/pidfd.h>.
Based on what I see in other mm tests, the following patch fixes my compilation issue.
[ ... patch snippet ... ]
Thank you very much for not only identifying the root cause but also providing a concrete patch to fix the compilation issue. Your analysis that selftests should be independent of userspace headers is spot on, and this approach aligns perfectly with the feedback I've received.
I have integrated your suggested changes into my local tree and will include them in the next version of the patch. I will also be sure to add your "Suggested-by" tag in the commit message to properly credit your contribution.
Your help has been invaluable.
Best regards, Wang Lian