Alisertib and Gemcitabine Hydrochloride in Treating Patients With Solid Tumors or Pancreatic Cancer

Inclusion Criteria: * Eligibility for dose escalation cohort: histologically or cytologically confirmed metastatic or unresectable solid tumor for which standard curative or palliative measures do not exist or are no longer effective * Eligibility for the expansion cohort: histologically or cytologically confirmed metastatic or unresectable pancreatic adenocarcinoma for which curative treatment does not exist * Zubrod (Eastern Cooperative Oncology Group \[ECOG\]) performance status 0 - 2 * Measurable or non-measurable disease. x-rays and/or scans for disease assessment of measurable disease must have been completed within 28 days prior to registration; non-measurable disease must also be assessed within 28 days prior to registration; (expansion - patients must have measurable disease) * Absolute neutrophil count (ANC) \>= 1,500/mm\^3 * Platelet count \>= 100,000/mm\^3 * Total bilirubin within institutional normal limits * Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) =\< 2.5 times institutional upper limit of normal or =\< 5 times institutional upper limit of normal in the presence of liver metastases * Creatinine =\< 1.5 times institutional upper limit of normal OR * Creatinine Clearance \>= 60ml/min/1.73m\^2 measured by 24-hour urine collection * Any number of prior chemotherapy regimens; up to two prior chemotherapy regimen in the palliative setting will be allowed in the expansion cohort. Prior gemcitabine-based regimes in the palliative setting …