scripts/gdb/stackdepot: rename pool_index to pools_num

After stackdepot evicting support patchset[1], we rename pool_index to
pools_num.

To avoid from the below issue, we rename consistently in
gdb scripts.

Python Exception <class 'gdb.error'>: No symbol "pool_index" in current
context.
Error occurred in Python: No symbol "pool_index" in current context.

[1] https://lore.kernel.org/linux-mm/cover.1700502145.git.andreyknvl@google.com/
Link: https://lkml.kernel.org/r/20231129065142.13375-3-Kuan-Ying.Lee@mediatek.comSigned-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Cc: Chinwen Chang <chinwen.chang@mediatek.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Qun-Wei Lin <qun-wei.lin@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

scripts/gdb/linux/stackdepot.py

@@ -25,10 +25,10 @@ def stack_depot_fetch(handle):
     handle_parts_t = gdb.lookup_type("union handle_parts")
     parts = handle.cast(handle_parts_t)
     offset = parts['offset'] << DEPOT_STACK_ALIGN
-    pool_index_cached = gdb.parse_and_eval('pool_index')
+    pools_num = gdb.parse_and_eval('pools_num')
 
-    if parts['pool_index'] > pool_index_cached:
-        gdb.write("pool index %d out of bounds (%d) for stack id 0x%08x\n" % (parts['pool_index'], pool_index_cached, handle))
+    if parts['pool_index'] > pools_num:
+        gdb.write("pool index %d out of bounds (%d) for stack id 0x%08x\n" % (parts['pool_index'], pools_num, handle))
         return gdb.Value(0), 0
 
     stack_pools = gdb.parse_and_eval('stack_pools')