Re: [PATCH] mm/vmalloc: Do not trigger BUG() on BH disabled context

[Uladzislau Rezki <urezki@gmail.com>]

On Tue, May 19, 2026 at 09:40:19AM +0800, Baoquan He wrote:
> On 05/15/26 at 05:30pm, Uladzislau Rezki (Sony) wrote:
> > __get_vm_area_node() currently triggers a BUG() if in_interrupt()
> > returns true. However, in_interrupt() also reports true when BH
> > are disabled.
> > 
> > The bridge code can call rhashtable_lookup_insert_fast() with
> > bottom halves disabled:
> > 
> > __vlan_add()
> >  -> br_fdb_add_local()
> >   spin_lock_bh(&br->hash_lock); <-- Disable BH
> >    -> fdb_add_local()
> >     -> fdb_create()
> >      -> rhashtable_lookup_insert_fast()
> >       -> kvmalloc()
> >        -> vmalloc()
> >         -> __get_vm_area_node()
> >          -> BUG_ON(in_interrupt())
> >   spin_unlock_bh(&br->hash_lock)
> > 
> > this triggers the BUG() despite the caller not being in NMI or
> > hard IRQ context.
> 
> Because the current vmalloc supports non-blocking allocation, so we
> need to skip disabled BH or in_serving_softirq() cases to avoid unwanted
> BUG(). This change looks great to me, not sure if I undersand it
> correctly.
> 
> Reviewed-by: Baoquan He <baoquan.he@linux.dev>
> 
Thank you!

--
Uladzislau Rezki