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Fix race condition where heap_delete() fails to pin VM page.

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Similar to 5f12bc94dc, the code must re-check PageIsAllVisible() after
buffer lock is re-acquired. Backpatching to the same version, 12.

Discussion: https://postgr.es/m/CAEP4nAw9jYQDKd_5Y+-s2E4YiUJq1vqiikFjYGpLShtp-K3gag@mail.gmail.com
Reported-by: Robins Tharakan
Reviewed-by: Robins Tharakan
Backpatch-through: 12
This commit is contained in:
Jeff Davis 2022-09-22 10:58:49 -07:00
parent 790bf615dd
commit 163b0993a1
1 changed files with 19 additions and 11 deletions
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30
src/backend/access/heap/heapam.c
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@ -2711,6 +2711,15 @@ heap_delete(Relation relation, ItemPointer tid,
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
lp = PageGetItemId(page, ItemPointerGetOffsetNumber(tid));
Assert(ItemIdIsNormal(lp));
tp.t_tableOid = RelationGetRelid(relation);
tp.t_data = (HeapTupleHeader) PageGetItem(page, lp);
tp.t_len = ItemIdGetLength(lp);
tp.t_self = *tid;
l1:
/*
* If we didn't pin the visibility map page and the page has become all
* visible while we were busy locking the buffer, we'll have to unlock and
@ -2724,15 +2733,6 @@ heap_delete(Relation relation, ItemPointer tid,
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
}
lp = PageGetItemId(page, ItemPointerGetOffsetNumber(tid));
Assert(ItemIdIsNormal(lp));
tp.t_tableOid = RelationGetRelid(relation);
tp.t_data = (HeapTupleHeader) PageGetItem(page, lp);
tp.t_len = ItemIdGetLength(lp);
tp.t_self = *tid;
l1:
result = HeapTupleSatisfiesUpdate(&tp, cid, buffer);
if (result == TM_Invisible)
@ -2791,8 +2791,12 @@ l1:
* If xwait had just locked the tuple then some other xact
* could update this tuple before we get to this point. Check
* for xmax change, and start over if so.
*
* We also must start over if we didn't pin the VM page, and
* the page has become all visible.
*/
if (xmax_infomask_changed(tp.t_data->t_infomask, infomask) ||
if ((vmbuffer == InvalidBuffer && PageIsAllVisible(page)) ||
xmax_infomask_changed(tp.t_data->t_infomask, infomask) ||
!TransactionIdEquals(HeapTupleHeaderGetRawXmax(tp.t_data),
xwait))
goto l1;
@ -2824,8 +2828,12 @@ l1:
* xwait is done, but if xwait had just locked the tuple then some
* other xact could update this tuple before we get to this point.
* Check for xmax change, and start over if so.
*
* We also must start over if we didn't pin the VM page, and the
* page has become all visible.
*/
if (xmax_infomask_changed(tp.t_data->t_infomask, infomask) ||
if ((vmbuffer == InvalidBuffer && PageIsAllVisible(page)) ||
xmax_infomask_changed(tp.t_data->t_infomask, infomask) ||
!TransactionIdEquals(HeapTupleHeaderGetRawXmax(tp.t_data),
xwait))
goto l1;