[Crash-utility] More fixes for kmem on slabs

[Dave Anderson]

----- Original Message -----

> But your patch does this:
> 
> @@ -8117,8 +8135,9 @@ kmem_cache_s_array_nodes:
>              "array cache array", RETURN_ON_ERROR))
>                 goto bail_out;
> 
> -       for (i = max_limit = 0; (i < ARRAY_LENGTH(kmem_cache_s_array)) &&
> -            cpudata[i]; i++) {
> +       for (i = max_limit = 0; (i < kmem_cache_nr_cpu)
> +                       && (i < ARRAY_LENGTH(kmem_cache_s_array))
> +                       && cpudata[i]; i++) {
>                  if (!readmem(cpudata[i]+OFFSET(array_cache_limit),
>                      KVADDR, &limit, sizeof(int),
>                      "array cache limit", RETURN_ON_ERROR))
> 
> On "old" slab systems, your new "kmem_cache_nr_cpu" variable remains at
> its initialized value of zero, and the loop never gets entered.  So I don't
> think you wanted to keep the (i < kmem_cache_nr_cpu) there, right?

How's this work for you?  (patch also attached)

--- crash-6.0.3/memory.c.orig
+++ crash-6.0.3/memory.c
@@ -7977,14 +7977,32 @@ kmem_cache_downsize(void)
        char *cache_buf;
        uint buffer_size; 
        int nr_node_ids;
+       int nr_cpu_ids;
 
        if ((THIS_KERNEL_VERSION < LINUX(2,6,22)) ||
-           (vt->flags & NODELISTS_IS_PTR) ||
            !(vt->flags & PERCPU_KMALLOC_V2_NODES) ||
            !kernel_symbol_exists("cache_cache") ||
            !MEMBER_EXISTS("kmem_cache", "buffer_size"))
                return;
 
+       if (vt->flags & NODELISTS_IS_PTR) {
+               /* 
+                * kmem_cache.array[] is actually sized by 
+                * the number of cpus; real value is nr_cpu_ids, 
+                * but fallback is kt->cpus.
+                */
+               if (kernel_symbol_exists("nr_cpu_ids"))
+                       get_symbol_data("nr_cpu_ids", sizeof(int), 
+                               &nr_cpu_ids);
+               else 
+                       nr_cpu_ids = kt->cpus;
+
+               ARRAY_LENGTH(kmem_cache_s_array) = nr_cpu_ids;
+               ASSIGN_SIZE(kmem_cache_s) = OFFSET(kmem_cache_s_array) +
+                       sizeof(ulong) * nr_cpu_ids;
+               return;
+       }
+
        cache_buf = GETBUF(SIZE(kmem_cache_s));
 
        if (!readmem(symbol_value("cache_cache"), KVADDR, cache_buf, 

Dave

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