sched/fair: Avoid pulling all tasks in idle balancing
sched/fair: Avoid pulling all tasks in idle balancing

In idle balancing where a CPU going idle pulls tasks from another CPU,
a livelock may happen if the CPU pulls all tasks from another, makes
it idle, and this iterates. So just avoid this.

Reported-by: Rabin Vincent <b8c38523cce7640aaeed4045bf245272d3b467e3@axis.com>
Signed-off-by: Yuyang Du <7bbcbf7f034930139b3e7cdc7068af37f6004f7b@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <3fddac958924aef220f202ca567388ddab3f14a8@infradead.org>
Cc: Ben Segall <7dc6b67dc6a1a2319718815cbe6519298041ac95@google.com>
Cc: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>
Cc: Mike Galbraith <3cfa3897b7f55b5396b7a47c83b66325184bc9b4@gmx.de>
Cc: Mike Galbraith <d1e2fad1f6337a0a3a08db0a5375a8a96150db4c@gmail.com>
Cc: Morten Rasmussen <4cb630890d50903d357308bfb549e0e4022cee38@arm.com>
Cc: Paul Turner <56b59ac50e86208fd62726b53c1d890b9a8ff058@google.com>
Cc: Peter Zijlstra <3fddac958924aef220f202ca567388ddab3f14a8@infradead.org>
Cc: Thomas Gleixner <00e4cf8f46a57000a44449bf9dd8cbbcc209fd2a@linutronix.de>
Link: 2bb66b50c47f3760345a846f5fda8beb3e2d26e4@intel.com
Signed-off-by: Ingo Molnar <9dbbbf0688fedc85ad4da37637f1a64b8c718ee2@kernel.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs