Subject: Re: [RFC 1/2] mm, slub: prevent kmalloc_node crashes and memory leaks

From: Srikar Dronamraju <[email-masked]>
Date: Fri, 20 Mar 2020 13:16:38 +0530

* Vlastimil Babka <[email-masked]> [2020-03-19 15:10:19]:

> On 3/19/20 3:05 PM, Srikar Dronamraju wrote:
> > * Vlastimil Babka <[email-masked]> [2020-03-19 14:47:58]:
> > 
> >> ----8<----
> >> diff --git a/mm/slub.c b/mm/slub.c
> >> index 17dc00e33115..7113b1f9cd77 100644
> >> --- a/mm/slub.c
> >> +++ b/mm/slub.c
> >> @@ -1973,8 +1973,6 @@ static void *get_partial(struct kmem_cache *s, gfp_t flags, int node,
> >> 
> >>  	if (node == NUMA_NO_NODE)
> >>  		searchnode = numa_mem_id();
> >> -	else if (!node_present_pages(node))
> >> -		searchnode = node_to_mem_node(node);
> >> 
> >>  	object = get_partial_node(s, get_node(s, searchnode), c, flags);
> > 
> > Are we okay with passing a node to get_partial_node with !NUMA_NO_NODE and
> > !N_MEMORY including possible nodes?
> 
> No, but AFAICS, such node values are already handled in ___slab_alloc, and
> cannot reach get_partial(). If you see something I missed, please do tell.
> 

Ah I probably got confused with your previous version where
alloc_slab_page() was modified. I see no problems with this version.

Sorry for the noise.

A question just for my better understanding,
How worse would it be to set node to numa_mem_id() instead of NUMA_NODE_ID
when the current node is !N_NORMAL_MEMORY?

> >>  	if (object || node != NUMA_NO_NODE)
> > 
> 

-- 
Thanks and Regards
Srikar Dronamraju