linux-stable.git/kernel, branch linux-3.3.y

workqueue: skip nr_running sanity check in worker_enter_idle() if trustee is active

2012-06-01T07:15:46+00:00

commit 544ecf310f0e7f51fa057ac2a295fc1b3b35a9d3 upstream.

worker_enter_idle() has WARN_ON_ONCE() which triggers if nr_running
isn't zero when every worker is idle.  This can trigger spuriously
while a cpu is going down due to the way trustee sets %WORKER_ROGUE
and zaps nr_running.

It first sets %WORKER_ROGUE on all workers without updating
nr_running, releases gcwq->lock, schedules, regrabs gcwq->lock and
then zaps nr_running.  If the last running worker enters idle
inbetween, it would see stale nr_running which hasn't been zapped yet
and trigger the WARN_ON_ONCE().

Fix it by performing the sanity check iff the trustee is idle.

Signed-off-by: Tejun Heo 
Reported-by: "Paul E. McKenney" 
Signed-off-by: Greg Kroah-Hartman

compat: Fix RT signal mask corruption via sigprocmask

2012-05-21T17:46:23+00:00

commit b7dafa0ef3145c31d7753be0a08b3cbda51f0209 upstream.

compat_sys_sigprocmask reads a smaller signal mask from userspace than
sigprogmask accepts for setting.  So the high word of blocked.sig[0]
will be cleared, releasing any potentially blocked RT signal.

This was discovered via userspace code that relies on get/setcontext.
glibc's i386 versions of those functions use sigprogmask instead of
rt_sigprogmask to save/restore signal mask and caused RT signal
unblocking this way.

As suggested by Linus, this replaces the sys_sigprocmask based compat
version with one that open-codes the required logic, including the merge
of the existing blocked set with the new one provided on SIG_SETMASK.

Signed-off-by: Jan Kiszka 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

namespaces, pid_ns: fix leakage on fork() failure

2012-05-21T17:46:17+00:00

commit 5e2bf0142231194d36fdc9596b36a261ed2b9fe7 upstream.

Fork() failure post namespace creation for a child cloned with
CLONE_NEWPID leaks pid_namespace/mnt_cache due to proc being mounted
during creation, but not unmounted during cleanup.  Call
pid_ns_release_proc() during cleanup.

Signed-off-by: Mike Galbraith 
Acked-by: Oleg Nesterov 
Reviewed-by: "Eric W. Biederman" 
Cc: Pavel Emelyanov 
Cc: Cyrill Gorcunov 
Cc: Louis Rilling 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

exit_signal: fix the "parent has changed security domain" logic

2012-05-07T15:53:36+00:00

commit b6e238dceed36891cc633167afe7151f1f3d83c5 upstream.

exit_notify() changes ->exit_signal if the parent already did exec.
This doesn't really work, we are not going to send the signal now
if there is another live thread or the exiting task is traced. The
parent can exec before the last dies or the tracer detaches.

Move this check into do_notify_parent() which actually sends the
signal.

The user-visible change is that we do not change ->exit_signal,
and thus the exiting task is still "clone children" for
do_wait()->eligible_child(__WCLONE). Hopefully this is fine, the
current logic is racy anyway.

Signed-off-by: Oleg Nesterov 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

exit_signal: simplify the "we have changed execution domain" logic

2012-05-07T15:53:35+00:00

commit e636825346b36a07ccfc8e30946d52855e21f681 upstream.

exit_notify() checks "tsk->self_exec_id != tsk->parent_exec_id"
to handle the "we have changed execution domain" case.

We can change do_thread() to always set ->exit_signal = SIGCHLD
and remove this check to simplify the code.

We could change setup_new_exec() instead, this looks more logical
because it increments ->self_exec_id. But note that de_thread()
already resets ->exit_signal if it changes the leader, let's keep
both changes close to each other.

Note that we change ->exit_signal lockless, this changes the rules.
Thereafter ->exit_signal is not stable under tasklist but this is
fine, the only possible change is OLDSIG -> SIGCHLD. This can race
with eligible_child() but the race is harmless. We can race with
reparent_leader() which changes our ->exit_signal in parallel, but
it does the same change to SIGCHLD.

The noticeable user-visible change is that the execing task is not
"visible" to do_wait()->eligible_child(__WCLONE) right after exec.
To me this looks more logical, and this is consistent with mt case.

Signed-off-by: Oleg Nesterov 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

sched: Fix nohz load accounting -- again!

2012-05-07T15:53:35+00:00

commit c308b56b5398779cd3da0f62ab26b0453494c3d4 upstream.

Various people reported nohz load tracking still being wrecked, but Doug
spotted the actual problem. We fold the nohz remainder in too soon,
causing us to loose samples and under-account.

So instead of playing catch-up up-front, always do a single load-fold
with whatever state we encounter and only then fold the nohz remainder
and play catch-up.

Reported-by: Doug Smythies 
Reported-by: LesÅ=82aw Kope=C4=87 
Reported-by: Aman Gupta 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-4v31etnhgg9kwd6ocgx3rxl8@git.kernel.org
Signed-off-by: Ingo Molnar 
Cc: Kerin Millar 
Signed-off-by: Greg Kroah-Hartman

PM / Hibernate: fix the number of pages used for hibernate/thaw buffering

2012-05-07T15:53:35+00:00

commit f8262d476823a7ea1eb497ff9676d1eab2393c75 upstream.

Hibernation regression fix, since 3.2.

Calculate the number of required free pages based on non-high memory
pages only, because that is where the buffers will come from.

Commit 081a9d043c983f161b78fdc4671324d1342b86bc introduced a new buffer
page allocation logic during hibernation, in order to improve the
performance. The amount of pages allocated was calculated based on total
amount of pages available, although only non-high memory pages are
usable for this purpose. This caused hibernation code to attempt to over
allocate pages on platforms that have high memory, which led to hangs.

Signed-off-by: Bojan Smojver 
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Greg Kroah-Hartman

tracing: Fix stacktrace of latency tracers (irqsoff and friends)

2012-05-07T15:53:21+00:00

commit db4c75cbebd7e5910cd3bcb6790272fcc3042857 upstream.

While debugging a latency with someone on IRC (mirage335) on #linux-rt (OFTC),
we discovered that the stacktrace output of the latency tracers
(preemptirqsoff) was empty.

This bug was caused by the creation of the dynamic length stack trace
again (like commit 12b5da3 "tracing: Fix ent_size in trace output" was).

This bug is caused by the latency tracers requiring the next event
to determine the time between the current event and the next. But by
grabbing the next event, the iter->ent_size is set to the next event
instead of the current one. As the stacktrace event is the last event,
this makes the ent_size zero and causes nothing to be printed for
the stack trace. The dynamic stacktrace uses the ent_size to determine
how much of the stack can be printed. The ent_size of zero means
no stack.

The simple fix is to save the iter->ent_size before finding the next event.

Note, mirage335 asked to remain anonymous from LKML and git, so I will
not add the Reported-by and Tested-by tags, even though he did report
the issue and tested the fix.

Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

sched: Fix OOPS when build_sched_domains() percpu allocation fails

2012-05-07T15:53:20+00:00

commit fb2cf2c660971bea0ad86a9a5c19ad39eab61344 upstream.

Under extreme memory used up situations, percpu allocation
might fail. We hit it when system goes to suspend-to-ram,
causing a kworker panic:

 EIP: [] build_sched_domains+0x23a/0xad0
 Kernel panic - not syncing: Fatal exception
 Pid: 3026, comm: kworker/u:3
 3.0.8-137473-gf42fbef #1

 Call Trace:
  [] panic+0x66/0x16c
  [...]
  [] partition_sched_domains+0x287/0x4b0
  [] cpuset_update_active_cpus+0x1fe/0x210
  [] cpuset_cpu_inactive+0x1d/0x30
  [...]

With this fix applied build_sched_domains() will return -ENOMEM and
the suspend attempt fails.

Signed-off-by: he, bo 
Reviewed-by: Zhang, Yanmin 
Reviewed-by: Srivatsa S. Bhat 
Signed-off-by: Peter Zijlstra 
Cc: Linus Torvalds 
Cc: Andrew Morton 
Link: http://lkml.kernel.org/r/1335355161.5892.17.camel@hebo
[ So, we fail to deallocate a CPU because we cannot allocate RAM :-/
  I don't like that kind of sad behavior but nevertheless it should
  not crash under high memory load. ]
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

futex: Do not leak robust list to unprivileged process

2012-04-22T22:39:18+00:00

commit bdbb776f882f5ad431aa1e694c69c1c3d6a4a5b8 upstream.

It was possible to extract the robust list head address from a setuid
process if it had used set_robust_list(), allowing an ASLR info leak. This
changes the permission checks to be the same as those used for similar
info that comes out of /proc.

Running a setuid program that uses robust futexes would have had:
  cred->euid != pcred->euid
  cred->euid == pcred->uid
so the old permissions check would allow it. I'm not aware of any setuid
programs that use robust futexes, so this is just a preventative measure.

(This patch is based on changes from grsecurity.)

Signed-off-by: Kees Cook 
Cc: Darren Hart 
Cc: Peter Zijlstra 
Cc: Jiri Kosina 
Cc: Eric W. Biederman 
Cc: David Howells 
Cc: Serge E. Hallyn 
Cc: kernel-hardening@lists.openwall.com
Cc: spender@grsecurity.net
Link: http://lkml.kernel.org/r/20120319231253.GA20893@www.outflux.net
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman