Re: [PATCH 6.15.y] mm/vmalloc: fix data race in show_numa_info()

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

✅ All tests passed successfully. No issues detected.
No action required from the submitter.

The upstream commit SHA1 provided is correct: 5c5f0468d172ddec2e333d738d2a1f85402cf0bc

Note: The patch differs from the upstream commit:
---
1:  5c5f0468d172d ! 1:  99ac6d1cf98b4 mm/vmalloc: fix data race in show_numa_info()
    @@ Metadata
      ## Commit message ##
         mm/vmalloc: fix data race in show_numa_info()
     
    +    commit 5c5f0468d172ddec2e333d738d2a1f85402cf0bc upstream.
    +
         The following data-race was found in show_numa_info():
     
         ==================================================================
    @@ Commit message
         m->private, vmalloc_info_show() should allocate the heap.
     
         Link: https://lkml.kernel.org/r/20250508165620.15321-1-aha310510@gmail.com
    -    Fixes: 8e1d743f2c26 ("mm: vmalloc: support multiple nodes in vmallocinfo")
    +    Fixes: 8e1d743 ("mm: vmalloc: support multiple nodes in vmallocinfo")
         Signed-off-by: Jeongjun Park <aha310510@gmail.com>
         Suggested-by: Eric Dumazet <edumazet@google.com>
         Suggested-by: Andrew Morton <akpm@linux-foundation.org>
    @@ mm/vmalloc.c: bool vmalloc_dump_obj(void *object)
      
      static void show_purge_info(struct seq_file *m)
     @@ mm/vmalloc.c: static int vmalloc_info_show(struct seq_file *m, void *p)
    - 	struct vmap_node *vn;
      	struct vmap_area *va;
      	struct vm_struct *v;
    + 	int i;
     +	unsigned int *counters;
     +
     +	if (IS_ENABLED(CONFIG_NUMA))
     +		counters = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL);
      
    - 	for_each_vmap_node(vn) {
    - 		spin_lock(&vn->busy.lock);
    + 	for (i = 0; i < nr_vmap_nodes; i++) {
    + 		vn = &vmap_nodes[i];
     @@ mm/vmalloc.c: static int vmalloc_info_show(struct seq_file *m, void *p)
      			}
      
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.15.y       |  Success    |  Success   |