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scylla-gdb.py: scylla small-objects: make freelist traversal more robust

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Traversing the span's freelist is known to generate "Cannot access
memory at address ..." errors, which is especially annoying when it
results in failed CI. Make this loop more robust: catch gdb.error coming
from it and just log a warning that some listed objects in the span may
be free ones.

Fixes: #27681

Closes scylladb/scylladb#27805
This commit is contained in:
Botond Dénes
2025-12-22 11:13:08 +02:00
committed by Pavel Emelyanov
parent f769e52877
commit ebb101f8ae
1 changed files with 9 additions and 4 deletions
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13
scylla-gdb.py
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@@ -5123,10 +5123,15 @@ class scylla_small_objects(gdb.Command):
span_end = int(span_start + span.size() * self._page_size)
# span's free list
span_next_free = span.page['freelist']
while span_next_free:
self._free_in_span.add(int(span_next_free))
span_next_free = span_next_free['next']
try:
span_next_free = span.page['freelist']
while span_next_free:
self._free_in_span.add(int(span_next_free))
span_next_free = span_next_free['next']
except gdb.error:
# This loop sometimes steps on "Cannot access memory at address", causing CI instability.
# Catch the exception and break the freelist traversal loop gracefully.
gdb.write(f"Warning: error traversing freelist of span [0x{span_start:x}, 0x{span_end:x}), some of the listed objects in this span may be free objects.\n")
return span_start, span_end