On 14.3.2021 19.23, Uladzislau Rezki wrote:

Also, using vmaloc test driver i can trigger a kernel BUG:

<snip>
[   24.627577] kernel BUG at mm/vmalloc.c:1272!

It seems that most tests indeed fail. Perhaps the vmalloc subsystem 
isn't very robust in face of fragmented virtual memory. What could be 
done to fix that?

In this patch, I could retry __alloc_vmap_area() with the whole region 
after failure of both [random, vend] and [vstart, random] but I'm not 
sure that would help much. Worth a try of course.

By the way, some of the tests in test_vmalloc.c don't check for 
vmalloc() failure, for example in full_fit_alloc_test().

-Topi