The local metadata btree has a NULL root page

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    • Type: Bug
    • Resolution: Unresolved
    • Priority: Major - P3
    • None
    • Affects Version/s: None
    • Component/s: Disagg CI-blocker
    • None
    • Storage Engines, Storage Engines - Foundations
    • SE Foundations - 2025-09-12, SE Foundations - 2025-09-26
    • 5

      We see a crash in the mongodb disagg integration branch because of seg fault.

      #0  0x0000ffffb302b9b4 in __pthread_kill_implementation () from /lib64/libc.so.6
      (gdb) bt
      #0  0x0000ffffb302b9b4 in __pthread_kill_implementation () from /lib64/libc.so.6
      #1  0x0000ffffb2fe23a0 in raise () from /lib64/libc.so.6
      #2  0x0000aaaaf3741164 in mongo::endProcessWithSignal (signalNum=signalNum@entry=11) at src/mongo/util/signal_handlers_synchronous.cpp:392
      #3  0x0000aaaaf3743734 in mongo::(anonymous namespace)::abruptQuitWithAddrSignal (signalNum=11, siginfo=0x317778d0cda0, ucontext_erased=<optimized out>) at src/mongo/util/signal_handlers_synchronous.cpp:324
      #4  <signal handler called>
      #5  __wt_row_search (cbt=cbt@entry=0x317778ab2000, srch_key=srch_key@entry=0x317778ab2120, insert=insert@entry=false, leaf=leaf@entry=0x0, leaf_safe=leaf_safe@entry=false, leaf_foundp=leaf_foundp@entry=0x0) at src/third_party/wiredtiger/src/btree/row_srch.c:434
      #6  0x0000aaaaed4d2860 in __cursor_row_search (cbt=0x317778ab2000, insert=false, leaf=0x0, leaf_foundp=0x0) at src/third_party/wiredtiger/src/btree/bt_cursor.c:573
      #7  __wt_btcur_search (cbt=cbt@entry=0x317778ab2000) at src/third_party/wiredtiger/src/btree/bt_cursor.c:826
      #8  0x0000aaaaee0908bc in __curfile_search (cursor=0x317778ab2000) at src/third_party/wiredtiger/src/cursor/cur_file.c:314
      #9  0x0000aaaaee06bd3c in __disagg_pick_up_checkpoint (session=session@entry=0x31777c200000, meta_lsn=<optimized out>) at src/third_party/wiredtiger/src/conn/conn_layered.c:289
      #10 0x0000aaaaee06da50 in __disagg_pick_up_checkpoint_meta (session=0x31777c200000, meta_item=0xffff866e60c8) at src/third_party/wiredtiger/src/conn/conn_layered.c:453
      #11 __wti_disagg_conn_config (session=session@entry=0x31777c200000, cfg=cfg@entry=0xffff866e6460, reconfig=reconfig@entry=true) at src/third_party/wiredtiger/src/conn/conn_layered.c:941
      #12 0x0000aaaaee07450c in __wti_conn_reconfig (session=session@entry=0x31777c200000, cfg=cfg@entry=0xffff866e6460) at src/third_party/wiredtiger/src/conn/conn_reconfig.c:436
      #13 0x0000aaaaee05869c in __conn_reconfigure (wt_conn=<optimized out>, config=<optimized out>) at src/third_party/wiredtiger/src/conn/conn_api.c
      

      The issue is that due to an unknown reason, the local metadata btree has a root page with a NULL page.

      (gdb) p btree->root
      $3 = {
        page = 0x0,
        home = 0x0,
        pindex_hint = 0,
        ref_changes = 0 '\000',
        flags = 1 '\001',
        flags_atomic = 0 '\000',
        __state = 3 '\003',
        addr = 0x0,
        key = {
          recno = 0,
          ikey = 0x0
        },
        page_del = 0x0
      }
      

            Assignee:
            Will Korteland
            Reporter:
            Chenhao Qu
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              Created:
              Updated: