select() states non-blocking pipe is readable, read() returns EAGAIN in RHEL5

Issue

• On two cluster nodes, we had two winbindd processes running in a 100% CPU cycle.

• strace'ing revealed the following:

  select(1033, [7 9 774 1024 1025 1026 1027 1029 1032], [1031], NULL, {12817, 174879}) = 6 (in [7 1024 1025 1026 1027 1029], left {12817, 174879})
  read(7, 0x7fff684702f0, 16)             = -1 EAGAIN (Resource temporarily unavailable)
  select(1033, [7 9 774 1024 1025 1026 1027 1029 1032], [1031], NULL, {12817, 174745}) = 6 (in [7 1024 1025 1026 1027 1029], left {12817, 174745})
  read(7, 0x7fff684702f0, 16)             = -1 EAGAIN (Resource temporarily unavailable)
  

• This went on indefinitely.  select() gave back, that fd #7 is readable. But trying to read() from it fails.