On Wed, Jan 16, 2019 at 02:42:32PM -0700, Jason Gunthorpe wrote: > On Wed, Jan 16, 2019 at 01:12:27PM -0800, Matthew Wilcox wrote: > > > > I don't think the comment explaining why the aglorithm is so special > > > should be deleted :) > > > > Fair, but I think it's in the wrong place. It should be up with the > > definition of RESERVED_PIDS, and it should probably say why! How about this: > > > > /* > > * We avoid reusing PIDs below this to prevent user processes receiving > > * signals which are intended for system daemons. > > */ > > #define RESERVED_PIDS 300 > > This is better, yes.. I assume this old behavior is to support old > init systems that rely on pid files and might experience a race when a > daemon dies if a new process is re-spawned into the old pid? Possibly ... I always heard it was for the purpose of signals, but some greybeard might be able to enlighten us. > > /* Allow allocation below RESERVED_PID the first time */ > > if (min > tmp->last_pid) > > min = tmp->last_pid; > > Not min = 1? I don't think it matters, does it?
