Re: [PATCH 1/2] mm/vmalloc: Add a safer version of find_vm_area() for debug

[Matthew Wilcox]

On Wed, Aug 30, 2023 at 11:03:59AM +0000, Joel Fernandes (Google) wrote:
> It is unsafe to dump vmalloc area information when trying to do so from
> some contexts. Add a safer trylock version of the same function to do a
> best-effort VMA finding and use it from vmalloc_dump_obj().
> 
> Reported-by: Zhen Lei <thunder.leizhen@xxxxxxxxxxxxxxx>
> Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
> Cc: rcu@xxxxxxxxxxxxxxx
> Cc: Zqiang <qiang.zhang1211@xxxxxxxxx>
> Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>

Reviewed-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>

I once started writing something similar, but got distracted and the
immediate problem got solved a different way.

It does make me wonder if we couldn't make this tree RCU-safe, but
that's obviously a much larger job.