Revision 73863ab028579ed98c4f1f36d016536b1b415344 authored by Anton Vorontsov on 31 May 2012, 23:26:23 UTC, committed by Linus Torvalds on 01 June 2012, 00:49:29 UTC
Current CPU hotplug code has some task->mm handling issues: 1. Working with task->mm w/o getting mm or grabing the task lock is dangerous as ->mm might disappear (exit_mm() assigns NULL under task_lock(), so tasklist lock is not enough). We can't use get_task_mm()/mmput() pair as mmput() might sleep, so we must take the task lock while handle its mm. 2. Checking for process->mm is not enough because process' main thread may exit or detach its mm via use_mm(), but other threads may still have a valid mm. To fix this we would need to use find_lock_task_mm(), which would walk up all threads and returns an appropriate task (with task lock held). clear_tasks_mm_cpumask() has all the issues fixed, so let's use it. Suggested-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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t3-l1-pi-3rt.tst
#
# rt-mutex test
#
# Op: C(ommand)/T(est)/W(ait)
# | opcode
# | | threadid: 0-7
# | | | opcode argument
# | | | |
# C: lock: 0: 0
#
# Commands
#
# opcode opcode argument
# schedother nice value
# schedfifo priority
# lock lock nr (0-7)
# locknowait lock nr (0-7)
# lockint lock nr (0-7)
# lockintnowait lock nr (0-7)
# lockcont lock nr (0-7)
# unlock lock nr (0-7)
# signal thread to signal (0-7)
# reset 0
# resetevent 0
#
# Tests / Wait
#
# opcode opcode argument
#
# prioeq priority
# priolt priority
# priogt priority
# nprioeq normal priority
# npriolt normal priority
# npriogt normal priority
# locked lock nr (0-7)
# blocked lock nr (0-7)
# blockedwake lock nr (0-7)
# unlocked lock nr (0-7)
# opcodeeq command opcode or number
# opcodelt number
# opcodegt number
# eventeq number
# eventgt number
# eventlt number
#
# 3 threads 1 lock PI
#
C: resetevent: 0: 0
W: opcodeeq: 0: 0
# Set schedulers
C: schedfifo: 0: 80
C: schedfifo: 1: 81
C: schedfifo: 2: 82
# T0 lock L0
C: locknowait: 0: 0
W: locked: 0: 0
# T1 lock L0
C: locknowait: 1: 0
W: blocked: 1: 0
T: prioeq: 0: 81
# T2 lock L0
C: locknowait: 2: 0
W: blocked: 2: 0
T: prioeq: 0: 82
# T0 unlock L0
C: unlock: 0: 0
# Wait until T2 got the lock
W: locked: 2: 0
W: unlocked: 0: 0
T: prioeq: 0: 80
# T2 unlock L0
C: unlock: 2: 0
W: locked: 1: 0
W: unlocked: 2: 0
C: unlock: 1: 0
W: unlocked: 1: 0
Computing file changes ...
