Re: [PATCH 6.12.y] mm/vmalloc: take vmap_purge_lock in shrinker

["Heiko Stübner" <heiko@sntech.de>]

Hi,

Am Freitag, 8. Mai 2026, 21:10:50 Mitteleuropäische Sommerzeit schrieb Sasha Levin:
> From: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
> 
> [ Upstream commit ec05f51f1e65bce95528543eb73fda56fd201d94 ]
> 
> decay_va_pool_node() can be invoked concurrently from two paths:
> __purge_vmap_area_lazy() when pools are being purged, and the shrinker via
> vmap_node_shrink_scan().
> 
> However, decay_va_pool_node() is not safe to run concurrently, and the
> shrinker path currently lacks serialization, leading to races and possible
> leaks.
> 
> Protect decay_va_pool_node() by taking vmap_purge_lock in the shrinker
> path to ensure serialization with purge users.
> 
> Link: https://lore.kernel.org/20260413192646.14683-1-urezki@gmail.com
> Fixes: 7679ba6b36db ("mm: vmalloc: add a shrinker to drain vmap pools")
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> Reviewed-by: Baoquan He <baoquan.he@linux.dev>
> Cc: chenyichong <chenyichong@uniontech.com>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> [ kept index-based loop instead of for_each_vmap_node() helper ]
> Signed-off-by: Sasha Levin <sashal@kernel.org>

it seems this fell through the cracks?

Because I don't see an applied message and couldn't find it in a 6.12
release up to now as well.

Would be nice to have in 6.12 though :-)


Thanks
Heiko

> ---
>  mm/vmalloc.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 1d2262fb54185..d4a42980b4d02 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -5204,6 +5204,7 @@ vmap_node_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
>  {
>  	int i;
>  
> +	guard(mutex)(&vmap_purge_lock);
>  	for (i = 0; i < nr_vmap_nodes; i++)
>  		decay_va_pool_node(&vmap_nodes[i], true);
>  
>