Extent.c: Avoid an rtree NULL-check.
The edge case in which pages_map returns (void *)PAGE can trigger an incorrect assertion failure. Avoid it.
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16
src/extent.c
16
src/extent.c
@ -893,8 +893,22 @@ extent_try_coalesce_impl(tsdn_t *tsdn, pac_t *pac, ehooks_t *ehooks,
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}
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/* Try to coalesce backward. */
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edata_t *prev = emap_lock_edata_from_addr(tsdn, pac->emap,
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edata_t *prev = NULL;
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if (edata_before_get(edata) != NULL) {
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/*
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* This is subtle; the rtree code asserts that its input
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* pointer is non-NULL, and this is a useful thing to
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* check. But it's possible that edata corresponds to
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* an address of (void *)PAGE (in practice, this has
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* only been observed on FreeBSD when address-space
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* randomization is on, but it could in principle happen
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* anywhere). In this case, edata_before_get(edata) is
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* NULL, triggering the assert.
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*/
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prev = emap_lock_edata_from_addr(tsdn, pac->emap,
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edata_before_get(edata), inactive_only);
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}
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if (prev != NULL) {
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bool can_coalesce = extent_can_coalesce(ecache, edata,
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prev);
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