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Nope, it's vm_map_ram() not being handled

Another suspicious one. Related to kasan/vmalloc?

Very likely the same as with ion:

# git grep vm_map_ram|grep xfs
fs/xfs/xfs_buf.c:                * vm_map_ram() will allocate auxiliary structures (e.g.
fs/xfs/xfs_buf.c:                       bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,

Aaargh, that's an embarassing miss.

It's a bit intricate because kasan_vmalloc_populate function is
currently set up to take a vm_struct not a vmap_area, but I'll see if I
can get something simple out this evening - I'm away for the first part
of next week.

For crashes in XFS, binder etc that implicate vm_map_ram, see:
https://lore.kernel.org/linux-mm/20191129154519.30964-1-dja@axtens.net/ (local)

The easiest way I found to repro the bug is
sudo modprobe i915 mock_selftest=-1

For lock warns, one that goes through the percpu alloc path, the patch
is already queued in mmots.

For Dmitry's latest one where there's an allocation in the
purge_vmap_area_lazy path that triggers a locking warning, you'll have
to wait until next week, sorry.

Regards,
Daniel