scripts/gdb/vmalloc: fix vmallocinfo error

The patch series "Mitigate a vmap lock contention" removes vmap_area_list,
which will break the gdb vmallocinfo command:

(gdb) lx-vmallocinfo
Python Exception <class 'gdb.error'>: No symbol "vmap_area_list" in current context.
Error occurred in Python: No symbol "vmap_area_list" in current context.

So we can instead use vmap_nodes to iterate all vmallocinfo.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Kuan-Ying Lee <[e-mail]>
Cc: Casper Li <[e-mail]>
Cc: AngeloGioacchino Del Regno <[e-mail]>
Cc: Chinwen Chang <[e-mail]>
Cc: Jan Kiszka <[e-mail]>
Cc: Kieran Bingham <[e-mail]>
Cc: Matthias Brugger <[e-mail]>
Cc: Qun-Wei Lin <[e-mail]>
Cc: Uladzislau Rezki (Sony) <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

scripts/gdb/linux/vmalloc.py

···
         if not constants.LX_CONFIG_MMU:
             raise gdb.GdbError("Requires MMU support")
 
-        vmap_area_list = gdb.parse_and_eval('vmap_area_list')
-        for vmap_area in lists.list_for_each_entry(vmap_area_list, vmap_area_ptr_type, "list"):
-            if not vmap_area['vm']:
-                gdb.write("0x%x-0x%x %10d vm_map_ram\n" % (vmap_area['va_start'], vmap_area['va_end'],
-                    vmap_area['va_end'] - vmap_area['va_start']))
-                continue
-            v = vmap_area['vm']
-            gdb.write("0x%x-0x%x %10d" % (v['addr'], v['addr'] + v['size'], v['size']))
-            if v['caller']:
-                gdb.write(" %s" % str(v['caller']).split(' ')[-1])
-            if v['nr_pages']:
-                gdb.write(" pages=%d" % v['nr_pages'])
-            if v['phys_addr']:
-                gdb.write(" phys=0x%x" % v['phys_addr'])
-            if v['flags'] & constants.LX_VM_IOREMAP:
-                gdb.write(" ioremap")
-            if v['flags'] & constants.LX_VM_ALLOC:
-                gdb.write(" vmalloc")
-            if v['flags'] & constants.LX_VM_MAP:
-                gdb.write(" vmap")
-            if v['flags'] & constants.LX_VM_USERMAP:
-                gdb.write(" user")
-            if v['flags'] & constants.LX_VM_DMA_COHERENT:
-                gdb.write(" dma-coherent")
-            if is_vmalloc_addr(v['pages']):
-                gdb.write(" vpages")
-            gdb.write("\n")
+        nr_vmap_nodes = gdb.parse_and_eval('nr_vmap_nodes')
+        for i in range(0, nr_vmap_nodes):
+            vn = gdb.parse_and_eval('&vmap_nodes[%d]' % i)
+            for vmap_area in lists.list_for_each_entry(vn['busy']['head'], vmap_area_ptr_type, "list"):
+                if not vmap_area['vm']:
+                    gdb.write("0x%x-0x%x %10d vm_map_ram\n" % (vmap_area['va_start'], vmap_area['va_end'],
+                        vmap_area['va_end'] - vmap_area['va_start']))
+                    continue
+                v = vmap_area['vm']
+                gdb.write("0x%x-0x%x %10d" % (v['addr'], v['addr'] + v['size'], v['size']))
+                if v['caller']:
+                    gdb.write(" %s" % str(v['caller']).split(' ')[-1])
+                if v['nr_pages']:
+                    gdb.write(" pages=%d" % v['nr_pages'])
+                if v['phys_addr']:
+                    gdb.write(" phys=0x%x" % v['phys_addr'])
+                if v['flags'] & constants.LX_VM_IOREMAP:
+                    gdb.write(" ioremap")
+                if v['flags'] & constants.LX_VM_ALLOC:
+                    gdb.write(" vmalloc")
+                if v['flags'] & constants.LX_VM_MAP:
+                    gdb.write(" vmap")
+                if v['flags'] & constants.LX_VM_USERMAP:
+                    gdb.write(" user")
+                if v['flags'] & constants.LX_VM_DMA_COHERENT:
+                    gdb.write(" dma-coherent")
+                if is_vmalloc_addr(v['pages']):
+                    gdb.write(" vpages")
+                gdb.write("\n")
 
 LxVmallocInfo()