softlockup: make detector be aware of task switch of processes hogging cpu

For now, soft lockup detector warns once for each case of process
softlockup.  But the thread 'watchdog/n' may not always get the cpu at the
time slot between the task switch of two processes hogging that cpu to
reset soft_watchdog_warn.

An example would be two processes hogging the cpu.  Process A causes the
softlockup warning and is killed manually by a user.  Process B
immediately becomes the new process hogging the cpu preventing the
softlockup code from resetting the soft_watchdog_warn variable.

This case is a false negative of "warn only once for a process", as there
may be a different process that is going to hog the cpu.  Resolve this by
saving/checking the task pointer of the hogging process and use that to
reset soft_watchdog_warn too.

[[email protected]: update comment]
Signed-off-by: chai wen <[email protected]>
Signed-off-by: Don Zickus <[email protected]>
Cc: Ingo Molnar <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions