[sqlsmith] Crash in GetOldestSnapshot()

Hi,

since updating master from c93d873..fc509cd, I see crashes in
GetOldestSnapshot() on update/delete returning statements.

I reduced the triggering statements down to this:
   update clstr_tst set d = d returning d;

Backtrace below.

regards,
Andreas

Program received signal SIGSEGV, Segmentation fault.
(gdb) bt
#0  GetOldestSnapshot () at snapmgr.c:422
#1  0x00000000004b8279 in init_toast_snapshot (toast_snapshot=0x7ffcd824b010) at tuptoaster.c:2314
#2  0x00000000004b83bc in toast_fetch_datum (attr=<optimized out>) at tuptoaster.c:1869
#3  0x00000000004b9ab5 in heap_tuple_untoast_attr (attr=0x18226c8) at tuptoaster.c:179
#4  0x00000000007f71ad in pg_detoast_datum_packed (datum=<optimized out>) at fmgr.c:2266
#5  0x00000000007cfc12 in text_to_cstring (t=0x18226c8) at varlena.c:186
#6  0x00000000007f5735 in FunctionCall1Coll (flinfo=flinfo@entry=0x18221c0, collation=collation@entry=0,
arg1=arg1@entry=25306824)at fmgr.c:1297
 
#7  0x00000000007f68ee in OutputFunctionCall (flinfo=0x18221c0, val=25306824) at fmgr.c:1946
#8  0x0000000000478bc1 in printtup (slot=0x1821f80, self=0x181ce48) at printtup.c:359
#9  0x00000000006f9c8e in RunFromStore (portal=portal@entry=0x177cbf8, direction=direction@entry=ForwardScanDirection,
count=count@entry=0,dest=0x181ce48) at pquery.c:1117
 
#10 0x00000000006f9d52 in PortalRunSelect (portal=portal@entry=0x177cbf8, forward=forward@entry=1 '\001', count=0,
count@entry=9223372036854775807,dest=dest@entry=0x181ce48) at pquery.c:942
 
#11 0x00000000006fb41e in PortalRun (portal=portal@entry=0x177cbf8, count=count@entry=9223372036854775807,
isTopLevel=isTopLevel@entry=1'\001', dest=dest@entry=0x181ce48, altdest=altdest@entry=0x181ce48,
completionTag=completionTag@entry=0x7ffcd824b920"") at pquery.c:787
 
#12 0x00000000006f822b in exec_simple_query (query_string=0x17db878 "update clstr_tst set d = d returning d;") at
postgres.c:1094
#13 PostgresMain (argc=<optimized out>, argv=argv@entry=0x1781ce0, dbname=0x1781b40 "regression", username=<optimized
out>)at postgres.c:4074
 
#14 0x000000000046c9bd in BackendRun (port=0x1786920) at postmaster.c:4262
#15 BackendStartup (port=0x1786920) at postmaster.c:3936
#16 ServerLoop () at postmaster.c:1693
#17 0x0000000000693044 in PostmasterMain (argc=argc@entry=3, argv=argv@entry=0x175d5f0) at postmaster.c:1301
#18 0x000000000046dd26 in main (argc=3, argv=0x175d5f0) at main.c:228
(gdb) list
417
418        if (OldestActiveSnapshot != NULL)
419            ActiveLSN = OldestActiveSnapshot->as_snap->lsn;
420
421        if (XLogRecPtrIsInvalid(RegisteredLSN) || RegisteredLSN > ActiveLSN)
422            return OldestActiveSnapshot->as_snap;
423
424        return OldestRegisteredSnapshot;
425    }
426
(gdb) bt full
#0  GetOldestSnapshot () at snapmgr.c:422       OldestRegisteredSnapshot = <optimized out>       RegisteredLSN =
<optimizedout>       ActiveLSN = <optimized out>
 
#1  0x00000000004b8279 in init_toast_snapshot (toast_snapshot=0x7ffcd824b010) at tuptoaster.c:2314       snapshot =
<optimizedout>
 
#2  0x00000000004b83bc in toast_fetch_datum (attr=<optimized out>) at tuptoaster.c:1869       toastrel = 0x7f8b4ca88920
     toastidxs = 0x18447c8       toastkey = {         sk_flags = 0,         sk_attno = 1,         sk_strategy = 3,
  sk_subtype = 0,         sk_collation = 100,         sk_func = {           fn_addr = 0x77c490 <oideq>,
fn_oid= 184,           fn_nargs = 2,           fn_strict = 1 '\001',           fn_retset = 0 '\000',           fn_stats
=2 '\002',           fn_extra = 0x0,           fn_mcxt = 0x18282a8,           fn_expr = 0x0         },
sk_argument= 34491       }       toastscan = <optimized out>       ttup = <optimized out>       toasttupDesc =
0x7f8b4ca88c50      result = 0x18422d8       toast_pointer = <optimized out>       ressize = 5735       residx =
<optimizedout>       nextidx = 0       numchunks = 3       chunk = <optimized out>       isnull = <optimized out>
chunkdata= <optimized out>       chunksize = <optimized out>       num_indexes = 1       validIndex = 0
SnapshotToast= {         satisfies = 0x112,         xmin = 3626283536,         xmax = 32764,         xip = 0xf8ac628,
     xcnt = 5221870,         subxip = 0x0,         subxcnt = 0,         suboverflowed = 0 '\000',
takenDuringRecovery= 0 '\000',         copied = 0 '\000',         curcid = 14,         speculativeToken = 0,
active_count= 260753304,         regd_count = 0,         ph_node = {           first_child = 0xf8ac680,
next_sibling= 0xa40000000000112,           prev_or_parent = 0x0         },         whenTaken = 274,         lsn = 0
 }       __func__ = "toast_fetch_datum"
 
#3  0x00000000004b9ab5 in heap_tuple_untoast_attr (attr=0x18226c8) at tuptoaster.c:179
No locals.
#4  0x00000000007f71ad in pg_detoast_datum_packed (datum=<optimized out>) at fmgr.c:2266
No locals.
#5  0x00000000007cfc12 in text_to_cstring (t=0x18226c8) at varlena.c:186       tunpacked = <optimized out>       result
=<optimized out>
 
#6  0x00000000007f5735 in FunctionCall1Coll (flinfo=flinfo@entry=0x18221c0, collation=collation@entry=0,
arg1=arg1@entry=25306824)at fmgr.c:1297       fcinfo = {         flinfo = 0x18221c0,         context = 0x0,
resultinfo= 0x0,         fncollation = 0,         isnull = 0 '\000',         nargs = 1,         arg = {25306824,
6868497,0, 25356976, 1966, 1966, 0, 25207736, 1966, 8470236, 1966, 1966, 140236265213248, 7113528, 0, 4, 1, 25358272,
0,309237645256, 140236281446912, 1966, 25349336, 25207736, 1966, 8470236, 1966, 1966, 140236265213248, 7113605, 47,
148110127398913,25346992, 25358272, 25346992, 1, 25348352, 6188273, 3689292519771913624, 140723934769840,
140723934770607,140723934769840, 0, 10024654, 140723934770200, 0, 140723934770544, 140236311507497, 4222418944,
140723934770544,0, 8226869, 0, 140236263291992, 25, 140723934769968, 24856000, 8232733, 140236263291992, 15294443587,
25,140723934770016, 1125891316908032, 0, 7849104, 281483566645432, 2, 0, 24651624, 0, 25, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
107,8192, 8240, 128, 755914244609, 16, 2, 481036337259, 0, 0, 532575944823, 0, 140236314839840, 8192, 1024, 8192, 0,
25304960,140236311549156},         argnull =
"\000\000\000\000\000\000\000\000\250\202\202\001\000\000\000\000\250\202\202\001\000\000\000\000p\203\202\001\000\000\000\000\000\004\000\000\000\000\000\000\000\004\000\000\000\000\000\000\360\264$\330\374\177\000\000H\316\201\001\000\000\000\000\b\261\200\001\000\000\000\000\002\000\000\000\000\000\000\000\360\264$\330\374\177\000\000\033\314`\000\000\000\000\000\000\000\000"
     }       result = <optimized out>       __func__ = "FunctionCall1Coll"
 
#7  0x00000000007f68ee in OutputFunctionCall (flinfo=0x18221c0, val=25306824) at fmgr.c:1946       result = <optimized
out>      pushed = 0 '\000'
 
#8  0x0000000000478bc1 in printtup (slot=0x1821f80, self=0x181ce48) at printtup.c:359       outputstr = <optimized out>
     thisState = <optimized out>       attr = <optimized out>       typeinfo = <optimized out>       myState =
0x181ce48      oldcontext = 0x180b108       buf = {         data = 0x182aac8 "",         len = 2,         maxlen =
1024,        cursor = 68       }       natts = 1       i = 0
 
#9  0x00000000006f9c8e in RunFromStore (portal=portal@entry=0x177cbf8, direction=direction@entry=ForwardScanDirection,
count=count@entry=0,dest=0x181ce48) at pquery.c:1117       oldcontext = 0x180b108       ok = <optimized out>
forward= 1 '\001'       current_tuple_count = 14       slot = 0x1821f80
 
#10 0x00000000006f9d52 in PortalRunSelect (portal=portal@entry=0x177cbf8, forward=forward@entry=1 '\001', count=0,
count@entry=9223372036854775807,dest=dest@entry=0x181ce48) at pquery.c:942       queryDesc = 0x0       direction =
<optimizedout>       nprocessed = <optimized out>       __func__ = "PortalRunSelect"
 
#11 0x00000000006fb41e in PortalRun (portal=portal@entry=0x177cbf8, count=count@entry=9223372036854775807,
isTopLevel=isTopLevel@entry=1'\001', dest=dest@entry=0x181ce48, altdest=altdest@entry=0x181ce48,
completionTag=completionTag@entry=0x7ffcd824b920"") at pquery.c:787       save_exception_stack = 0x7ffcd824b9a0
save_context_stack= 0x0       local_sigjmp_buf = {{           __jmpbuf = {25020000, 8117249591578047072, 25020088, 2,
25284168,24503472, -8115502085312499104, 8117247189865575008},           __mask_was_saved = 0,           __saved_mask =
{            __val = {8368164, 1, 24911592, 10273694, 2, 1, 2, 140723934771202, 88, 24628216, 25020088, 2, 8459620,
25020000,2, 24628216}           }         }}       result = <optimized out>       nprocessed = <optimized out>
saveTopTransactionResourceOwner= 0x1782df8       saveTopTransactionContext = 0x175e4b0       saveActivePortal = 0x0
 saveResourceOwner = 0x1782df8       savePortalContext = 0x0       saveMemoryContext = 0x175e4b0       __func__ =
"PortalRun"
#12 0x00000000006f822b in exec_simple_query (query_string=0x17db878 "update clstr_tst set d = d returning d;") at
postgres.c:1094      parsetree = 0x17dc660       portal = 0x177cbf8       snapshot_set = <optimized out>
commandTag= <optimized out>       completionTag = "\000ELECT 1\000\377\377\177", '\000' <repeats 12 times>,
"\240\364\272O\213\177\000\000\000\000\000\000\000\000\000\000\"\000\000\000\000\000\000\000\330\367u\001\000\000\000\000\310\327u\001\000\000\000"
     querytree_list = <optimized out>       plantree_list = <optimized out>       receiver = 0x181ce48       format = 0
     dest = DestRemote       parsetree_list = 0x17dc6e0       save_log_statement_stats = 0 '\000'       was_logged = 0
'\000'      msec_str = "\310\317$\330\374\177", '\000' <repeats 25 times>       parsetree_item = 0x17dc6b8
isTopLevel= 1 '\001'
 
#13 PostgresMain (argc=<optimized out>, argv=argv@entry=0x1781ce0, dbname=0x1781b40 "regression", username=<optimized
out>)at postgres.c:4074       query_string = 0x17db878 "update clstr_tst set d = d returning d;"       firstchar =
25020000      input_message = {         data = 0x17db878 "update clstr_tst set d = d returning d;",         len = 40,
     maxlen = 1024,         cursor = 40       }       local_sigjmp_buf = {{           __jmpbuf = {24648928,
8117247467474629216,24648480, 0, 0, 24636608, -8115502085385899424, 8117247183479878240},           __mask_was_saved =
1,          __saved_mask = {             __val = {0, 24648856, 24648480, 24648512, 1024, 140723934771904, 24648928, 0,
8459304,24632953, 8454626, 13256160, 140723934771904, 24648928, 8376332, 24633416}           }         }}
send_ready_for_query= 0 '\000'       disable_idle_in_transaction_timeout = <optimized out>       __func__ =
"PostgresMain"