On 2020-08-12 14:45:22 [+0200], Thomas Graziadei wrote:

Hi Sebastian,

Hi Thomas,

any progress on your side?

Do you think the patch could be applied for the next versions?

Yes.  The ->active_mm change needs to be protected against scheduling
regardless of the arch/mmu. Otherwise the mm will be put twice. For this
to trigger you need to exec from a kernel thread and get preempted.
This will be addressed in use_mm() by commit
    38cf307c1f201 ("mm: fix kthread_use_mm() vs TLB invalidate")

which is in v5.9-rc1 and exec_mmap() is under discussion at
    https://lore.kernel.org/linux-arch/20200828100022.1099682-2-npiggin@gmail.com/ (local)

Regards,
Thomas

Sebastian