What is the test for a prison official to be liable under the Eighth Amendment for denying an inmate humane conditions of confinement?

Second, from a subjective point of view, a plaintiff must allege that the defendants acted with a sufficiently culpable state of mind, i.e., with "deliberate indifference." Wilson v. Seiter, 501 U.S. 294, 298-99 (1991). "A prison official cannot be found liable under the Eighth Amendment for denying an inmate humane conditions of confinement unless the official knows of and disregards an excessive risk to inmate health or safety; the official must both be aware of facts from which the inference could be drawn that a substantial risk of serious harm exists, and he must also draw the inference." Farmer, 511 U.S. at 837.