12 Jun
2025
12 Jun
'25
2:58 p.m.
On Thu, Jun 12, 2025 at 04:27:41PM +0200, Thomas Weißschuh wrote:
If the assumption is that this is most likely a kernel bug, shouldn't it be fixed properly rather than worked around? After all the job of a selftest is to detect bugs to be fixed.
I investigated the history for a bit and it seems likely we cannot change the kernel here. Call it an undocumented "feature".
MAP_HUGETLBFS rounds up the length to some value, userspace has to figure that out and not pass incorrect lengths. The selftest is doing that wrong.
If the test is broken on ARM64 64k in general then I am also wondering how it didn't fail before my change to the selftest harness.
It got lucky and didn't overmap something important.
Jason