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b0827819b0
Michael Kerrisk noticed that creating SCHED_DEADLINE reservations
with certain parameters (e.g, a runtime of something near 2^64 ns)
can cause a system freeze for some amount of time.
The problem is that in the interface we have
u64 sched_runtime;
while internally we need to have a signed runtime (to cope with
budget overruns)
s64 runtime;
At the time we setup a new dl_entity we copy the first value in
the second. The cast turns out with negative values when
sched_runtime is too big, and this causes the scheduler to go crazy
right from the start.
Moreover, considering how we deal with deadlines wraparound
(s64)(a - b) < 0
we also have to restrict acceptable values for sched_{deadline,period}.
This patch fixes the thing checking that user parameters are always
below 2^63 ns (still large enough for everyone).
It also rewrites other conditions that we check, since in
__checkparam_dl we don't have to deal with deadline wraparounds
and what we have now erroneously fails when the difference between
values is too big.
Reported-by: Michael Kerrisk <mtk.manpages@gmail.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Cc: Dario Faggioli<raistlin@linux.it>
Cc: Dave Jones <davej@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140513141131.20d944f81633ee937f256385@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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| .. | ||
| auto_group.c | ||
| auto_group.h | ||
| clock.c | ||
| completion.c | ||
| core.c | ||
| cpuacct.c | ||
| cpuacct.h | ||
| cpudeadline.c | ||
| cpudeadline.h | ||
| cpupri.c | ||
| cpupri.h | ||
| cputime.c | ||
| deadline.c | ||
| debug.c | ||
| fair.c | ||
| features.h | ||
| idle.c | ||
| idle_task.c | ||
| Makefile | ||
| proc.c | ||
| rt.c | ||
| sched.h | ||
| stats.c | ||
| stats.h | ||
| stop_task.c | ||
| wait.c | ||