Study of BKM120 & Rituximab in Patients With Relapsed or Refractory Indolent B-Cell Lymphoma

Inclusion Criteria:

* Patients must have histologically confirmed indolent B-cell NHL or mantle cell lymphoma; acceptable subtypes of indolent B-cell NHL include follicular lymphoma (grades 1, 2, or 3a), marginal zone lymphoma, or lymphoplasmacytic lymphoma/Waldenstrom's macroglobulinemia; patients with mantle cell lymphoma must have a documented t(11;14) or overexpression of cyclin D1 by immunohistochemical evaluation; patients with active large cell transformation are not eligible; however, patients with a history of large cell transformation are eligible provided that there is no current clinical evidence of active transformed lymphoma
* Eastern Cooperative Oncology Group (ECOG) performance status 0-2
* At least one prior therapy; prior autologous or allogeneic stem cell transplant is allowed; patients may not be on chronic immunosuppressive therapy for graft-versus-host disease (GVHD); patients who have received prior treatment with a pan-selective PI3K inhibitor are not eligible; however, prior therapy with a selective PI3K inhibitor, Bruton's tyrosine kinase inhibitor, or other B-cell receptor targeting agents is allowed
* Serum creatinine =\< 2.0 mg/dL
* Total bilirubin =\< upper limit of normal
* Aspartate aminotransferase (AST)/alanine aminotransferase (ALT) =\< 2.0 x upper limit of normal
* Absolute neutrophil count (ANC) \>= 750/mm\^3
* Platelets \>= 50,000/ mm\^3
* Serum lipase =\< upper limit of normal
* Serum amylase =\< upper limit of normal
* International normalized ratio (INR) =\< 2.0
* Fasting glucose \< 120mg/dL
* Recovery to =\< grade 1 toxicities associated with prior therapy
* Negative serum pregnancy test; if, on cycle 1 day 1, greater than 72 hours has elapsed since the last negative result, a serum pregnancy test must be repeated and be negative on cycle 1 day 1 (C1D1) for the patient to remain eligible
* Patient has the ability and willingness to provide informed consent and has signed the informed consent document

Exclusion Criteria:

* Pregnant or breast-feeding women and women of childbearing age or men who are unwilling to use adequate contraception; females of childbearing age and potential (i.e., not surgically sterilized) must use a second form of contraception, including total abstinence, intra-uterine device, double-barrier contraception, or other non-hormonal form of contraception
* Patients with a history of central nervous system involvement by lymphoma
* The presence of co-existing medical conditions that would limit compliance with study medications, including, but not limited to active infection, active or untreated cardiac or pulmonary disease, or malignancy
* Patients with significant, symptomatic deterioration of lung function confirmed by spirometry, diffusion capacity of carbon monoxide (DLCO), or resting oxygen (O2) saturation
* Patients with impairment of gastrointestinal function that may alter the absorption of BKM120
* Patients currently being actively treated or who have been treated within the past 3 years for an unrelated malignancy (except non-melanoma skin cancer, cervical carcinoma in-situ, and low risk prostate cancer)
* Patients who have undergone major surgery within 2 weeks prior to study enrollment or who have not recovered from a major surgery
* Patients with known human immunodeficiency virus (HIV), hepatitis B or hepatitis C (active or carriers)
* Patients with a fasting blood glucose \>= 120 mg/dL (6.7mmol/L); patients with diabetes mellitus are eligible if they require oral agents only and have a fasting blood glucose =\< 120 mg/dL; patients with a history of diabetes mellitus who require daily long-acting or mealtime insulin are not eligible; patients who have previously required treatment for hyperglycemia due to steroids or other medications are eligible as long as they have not required insulin or any other oral agent within 2 months prior to study enrollment
* Patients who are on chronic steroids for unrelated conditions (i.e. rheumatologic conditions) are not eligible if their total daily dose of steroids is \>= 10mg prednisone
* Patients with a known hypersensitivity to BKM120 or its excipients
* Patients with active moderate or severe major mood or psychiatric disorder as judged by the investigator, primary care physician, counselor, psychiatrist, or as a result of the patient's mood assessment questionnaire that may interfere with the ability to comply with the trial; in addition, given the prior mood-associated toxicities, patients with a history of psychiatric hospitalization within the past 5 years, electroconvulsive therapy (ECT) within the past 5 years, or whose psychiatric condition has been unstable within 2 months prior to study enrollment requiring addition or change of psychotropic medications are not eligible; examples include, but are not limited to:

  * Medically documented history of or active major depressive episode requiring inpatient or intensive outpatient therapy, bipolar disorder (I or II), obsessive-compulsive disorder, schizophrenia, a history of suicidal attempt or active ideation, or homicidal ideation (immediate risk of doing harm to others); patients under the care of a primary care physician who are treated with one oral agent and who have not required dose adjustments or new medications within 2 months prior to study enrollment and who otherwise meet eligibility requirements may be enrolled
  * \>= Common Terminology for Adverse Events (CTCAE) version 4.0 grade 3 anxiety
  * Patients meeting the cutoff score of \>= 12 in the Patient Health Questionnaire-9 (PHQ-9) or a cut-off of \>= 15 in the Generalized Anxiety Disorder-7 (GAD-7) mood scale, respectively, or who select a positive response of "1, 2, or 3" to question number 9 regarding potential for suicidal thoughts in the PHQ-9 (independent of the total score of the PHQ-9) are not eligible
* Patients with diarrhea \>= CTCAE grade 2
* Patients with active cardiac disease including any of the following:

  * Left ventricular ejection fraction \< 50% as determined by multi gated acquisition scan (MUGA) scan or echocardiogram
  * Corrected QT interval (QTc) \> 480 msec on screening ECG (using the QTcF formula)
  * Active angina pectoris
  * Ventricular arrhythmias except for benign premature ventricular contractions
  * Supraventricular or nodal arrhythmias or any conduction abnormality requiring a pacemaker or automatic implantable cardioverter defibrillator (AICD)
  * Valvular disease with documented compromise in cardiac function
  * Symptomatic pericarditis
  * Myocardial infarction within the past 6 months
  * Congestive heart failure (New York Heart Association \[NYHA\] functional classification III-IV)
* Patients who are currently receiving treatment with medications with a known risk to prolong the QT interval or inducing Torsades de Pointes and the treatment cannot either be discontinued or switched to a different medication prior to study enrollment
* Patients who have taken herbal medications and certain fruits within 7 days prior to study enrollment are not eligible; herbal medications include, but are not limited to, St John's wort, Kava, ephedra (ma huang), gingko biloba, dehydroepiandrosterone (DHEA), yohimbe, saw palmetto, and ginseng; exclusionary fruits include the cytochrome P450 family 3, subfamily A, polypeptide 4 (CYP3A) inhibitors Seville oranges, grapefruit, pummelos, or exotic citrus fruits
* Patients who are currently treated with drugs known to be moderate and strong inhibitors or inducers of isoenzyme CYP3A, and the treatment cannot be discontinued or switched to a different medication prior to study enrollment; (please note that co-treatment with weak inhibitors of CYP3A is allowed)
* Patients who have received oral or IV chemotherapy, targeted anticancer therapy or radiation therapy =\< 4 weeks (6 weeks for nitrosourea, antibodies or mitomycin-C) prior to study enrollment
* Patients who are currently taking therapeutic doses of warfarin sodium or any other Coumadin-derivative anticoagulant; patients who can be safely changed to enoxaparin or other non-warfarin derived anti-coagulant and who otherwise meet eligibility requirements may be enrolled