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Commit0bada39

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Fix inplace update buffer self-deadlock.
A CacheInvalidateHeapTuple* callee might callCatalogCacheInitializeCache(), which needs a relcache entry. Acquiringa valid relcache entry might scan pg_class. Hence, to preventundetected LWLock self-deadlock, CacheInvalidateHeapTuple* callers mustnot hold BUFFER_LOCK_EXCLUSIVE on buffers of pg_class. Move theCacheInvalidateHeapTupleInplace() before the BUFFER_LOCK_EXCLUSIVE. Noback-patch, since I've reverted commit243e9b4 from non-master branches.Reported by Alexander Lakhin. Reviewed by Alexander Lakhin.Discussion:https://postgr.es/m/10ec0bc3-5933-1189-6bb8-5dec4114558e@gmail.com
1 parentb412f40 commit0bada39

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3 files changed

+26
-8
lines changed

3 files changed

+26
-8
lines changed

‎src/backend/access/heap/heapam.c

Lines changed: 13 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -6214,6 +6214,17 @@ heap_inplace_lock(Relation relation,
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62156215
Assert(BufferIsValid(buffer));
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6217+
/*
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* Construct shared cache inval if necessary. Because we pass a tuple
6219+
* version without our own inplace changes or inplace changes other
6220+
* sessions complete while we wait for locks, inplace update mustn't
6221+
* change catcache lookup keys. But we aren't bothering with index
6222+
* updates either, so that's true a fortiori. After LockBuffer(), it
6223+
* would be too late, because this might reach a
6224+
* CatalogCacheInitializeCache() that locks "buffer".
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*/
6226+
CacheInvalidateHeapTupleInplace(relation,oldtup_ptr,NULL);
6227+
62176228
LockTuple(relation,&oldtup.t_self,InplaceUpdateTupleLock);
62186229
LockBuffer(buffer,BUFFER_LOCK_EXCLUSIVE);
62196230

@@ -6309,6 +6320,7 @@ heap_inplace_lock(Relation relation,
63096320
if (!ret)
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{
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UnlockTuple(relation,&oldtup.t_self,InplaceUpdateTupleLock);
6323+
ForgetInplace_Inval();
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InvalidateCatalogSnapshot();
63136325
}
63146326
returnret;
@@ -6345,14 +6357,6 @@ heap_inplace_update_and_unlock(Relation relation,
63456357
dst= (char*)htup+htup->t_hoff;
63466358
src= (char*)tuple->t_data+tuple->t_data->t_hoff;
63476359

6348-
/*
6349-
* Construct shared cache inval if necessary. Note that because we only
6350-
* pass the new version of the tuple, this mustn't be used for any
6351-
* operations that could change catcache lookup keys. But we aren't
6352-
* bothering with index updates either, so that's true a fortiori.
6353-
*/
6354-
CacheInvalidateHeapTupleInplace(relation,tuple,NULL);
6355-
63566360
/* Like RecordTransactionCommit(), log only if needed */
63576361
if (XLogStandbyInfoActive())
63586362
nmsgs=inplaceGetInvalidationMessages(&invalMessages,
@@ -6481,6 +6485,7 @@ heap_inplace_unlock(Relation relation,
64816485
{
64826486
LockBuffer(buffer,BUFFER_LOCK_UNLOCK);
64836487
UnlockTuple(relation,&oldtup->t_self,InplaceUpdateTupleLock);
6488+
ForgetInplace_Inval();
64846489
}
64856490

64866491
#defineFRM_NOOP0x0001

‎src/backend/utils/cache/inval.c

Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1201,6 +1201,18 @@ AtInplace_Inval(void)
12011201
inplaceInvalInfo=NULL;
12021202
}
12031203

1204+
/*
1205+
* ForgetInplace_Inval
1206+
*Alternative to PreInplace_Inval()+AtInplace_Inval(): discard queued-up
1207+
*invalidations. This lets inplace update enumerate invalidations
1208+
*optimistically, before locking the buffer.
1209+
*/
1210+
void
1211+
ForgetInplace_Inval(void)
1212+
{
1213+
inplaceInvalInfo=NULL;
1214+
}
1215+
12041216
/*
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* AtEOSubXact_Inval
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*Process queued-up invalidation messages at end of subtransaction.

‎src/include/utils/inval.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -30,6 +30,7 @@ extern void AtEOXact_Inval(bool isCommit);
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3131
externvoidPreInplace_Inval(void);
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externvoidAtInplace_Inval(void);
33+
externvoidForgetInplace_Inval(void);
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3435
externvoidAtEOSubXact_Inval(boolisCommit);
3536

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