LoadChainTip requires cs_main to be locked. Under some conditions, it may call ActivateBestChain. However, ActivateBestChain requires cs_main NOT to be taken when called.
{
    CTxUndo txundo;
    UpdateCoins(tx, inputs, txundo, nHeight);
}
bool CScriptCheck::operator()() {
    const CScript &scriptSig = ptxTo->vin[nIn].scriptSig;
    const CScriptWitness *witness = &ptxTo->vin[nIn].scriptWitness;
    return VerifyScript(scriptSig, m_tx_out.scriptPubKey, witness, nFlags, CachingTransactionSignatureChecker(ptxTo, nIn, m_tx_out.nValue, cacheStore, *txdata), &error);
}
int GetSpendHeight(const CCoinsViewCache& inputs)
{
    LOCK(cs_main);
    CBlockIndex* pindexPrev = LookupBlockIndex(inputs.GetBestBlock());
    return pindexPrev->nHeight + 1;
}
static CuckooCache::cache<uint256, SignatureCacheHasher> scriptExecutionCache;
static uint256 scriptExecutionCacheNonce(GetRandHash());
void InitScriptExecutionCache() {