Valproic Acid in Treating Patients With Previously Treated Non-Hodgkin Lymphoma, Hodgkin Lymphoma, or Chronic Lymphocytic Leukemia

DISEASE CHARACTERISTICS: * Diagnosis of relapsed or refractory Hodgkin lymphoma (HL), non-Hodgkin lymphoma (NHL), or chronic lymphocytic leukemia (CLL ) * Patient must have evaluable or measurable disease * Have failed prior treatment, as evidenced by 1 of the following: * Aggressive NHL * Failed at least 1 regimen containing rituximab and CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) (unless anthracyclines are contraindicated) in addition to another salvage regimen (unless it is determined by the treating physician that it is to the patient's best interest to receive valproic acid after the first relapse) * Hodgkin lymphoma * Failed ABVD (doxorubicin, bleomycin, vinblastine, and dacarbazine) and received salvage chemotherapy with at least 1 salvage combination regimen * Indolent or low-grade lymphoma * Failed at least 1 combination regimen containing rituximab (patients who are intolerant to the available therapies or have contraindications for them are eligible for the study) * No CNS involvement by lymphoma PATIENT CHARACTERISTICS: * ECOG performance status 0-2 * Absolute granulocyte count ≥ 1,000/mm\^3 * Platelet count ≥ 50,000/µL * AST and ALT ≤ 3 times upper limit of normal * Creatinine ≤ 2.0 mg/dL * Bilirubin ≤ 1.5 mg/dL * Not pregnant or nursing * Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: * More than 14 days since prior anticancer treatment * Prior high-dose chemotherapy with transplant allowed * No prior valproic acid * No concurrent corticosteroids