linux-toradex.git/kernel, branch v2.6.16.5

[PATCH] RCU signal handling

2006-04-11T16:46:41+00:00

made this BUG_ON() unsafe. This code runs under ->siglock,
while switch_exec_pids() takes tasklist_lock.

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

[PATCH] Fix module refcount leak in __set_personality()

2006-04-07T16:44:29+00:00

If the change of personality does not lead to change of exec domain,
__set_personality() returned without releasing the module reference
acquired by lookup_exec_domain().

This patch was already included in Linus' tree.

Signed-off-by: Sergey Vlasov 
Cc: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Signed-off-by: Adrian Bunk 
Signed-off-by: Greg Kroah-Hartman

[PATCH] wrong error path in dup_fd() leading to oopses in RCU

2006-04-07T16:44:28+00:00

Wrong error path in dup_fd() - it should return NULL on error,
not an address of already freed memory :/

Triggered by OpenVZ stress test suite.

What is interesting is that it was causing different oopses in RCU like
below:
Call Trace:
   [] rcu_do_batch+0x2c/0x80
   [] rcu_process_callbacks+0x3d/0x70
   [] tasklet_action+0x73/0xe0
   [] __do_softirq+0x10a/0x130
   [] do_softirq+0x4f/0x60
   =======================
   [] smp_apic_timer_interrupt+0x77/0x110
   [] apic_timer_interrupt+0x1c/0x24
  Code:  Bad EIP value.
   <0>Kernel panic - not syncing: Fatal exception in interrupt

Signed-Off-By: Pavel Emelianov 
Signed-Off-By: Dmitry Mishin 
Signed-Off-By: Kirill Korotaev 
Signed-Off-By: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

[PATCH] fix scheduler deadlock

2006-03-28T06:47:31+00:00

We have noticed lockups during boot when stress testing kexec on ppc64.
Two cpus would deadlock in scheduler code trying to grab already taken
spinlocks.

The double_rq_lock code uses the address of the runqueue to order the
taking of multiple locks.  This address is a per cpu variable:

	if (rq1 < rq2) {
		spin_lock(&rq1->lock);
		spin_lock(&rq2->lock);
	} else {
		spin_lock(&rq2->lock);
		spin_lock(&rq1->lock);
	}

On the other hand, the code in wake_sleeping_dependent uses the cpu id
order to grab locks:

	for_each_cpu_mask(i, sibling_map)
		spin_lock(&cpu_rq(i)->lock);

This means we rely on the address of per cpu data increasing as cpu ids
increase.  While this will be true for the generic percpu implementation it
may not be true for arch specific implementations.

One way to solve this is to always take runqueues in cpu id order. To do
this we add a cpu variable to the runqueue and check it in the
double runqueue locking functions.

Signed-off-by: Anton Blanchard 
Acked-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Chris Wright 
Signed-off-by: Greg Kroah-Hartman

[PATCH] disable unshare(CLONE_VM) for now

2006-03-18T18:49:36+00:00

sys_unshare() does mmput(new_mm).  This is not enough if we have
mm->core_waiters.

This patch is a temporary fix for soon to be released 2.6.16.

Signed-off-by: Oleg Nesterov 
[ Checked with Uli: "I'm not planning to use unshare(CLONE_VM).  It's
  not needed for any functionality planned so far.  What we (as in Red
  Hat) need unshare() for now is the filesystem side." ]
Signed-off-by: Linus Torvalds

[PATCH] posix-timers: fix requeue accounting when signal is ignored

2006-03-17T15:51:25+00:00

When the posix-timer signal is ignored then the timer is rearmed by the
callback function.  The requeue pending accounting has to be fixed up else
the state might be wrong.

Signed-off-by: Roman Zippel 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] time_interpolator: add __read_mostly

2006-03-17T15:51:25+00:00

The pointer to the current time interpolator and the current list of time
interpolators are typically only changed during bootup.  Adding
__read_mostly takes them away from possibly hot cachelines.

Signed-off-by: Christoph Lameter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] unshare: Use rcu_assign_pointer when setting sighand

2006-03-17T15:46:59+00:00

The sighand pointer only needs the rcu_read_lock on the
read side.  So only depending on task_lock protection
when setting this pointer is not enough.  We also need
a memory barrier to ensure the initialization is seen first.

Use rcu_assign_pointer as it does this for us, and clearly
documents that we are setting an rcu readable pointer.

Signed-off-by: Eric W. Biederman 
Acked-by: Paul E. McKenney 
Signed-off-by: Linus Torvalds

[PATCH] Fix sigaltstack corruption among cloned threads

2006-03-14T15:57:17+00:00

This patch fixes alternate signal stack corruption among cloned threads
with CLONE_SIGHAND (and CLONE_VM) for linux-2.6.16-rc6.

The value of alternate signal stack is currently inherited after a call of
clone(...  CLONE_SIGHAND | CLONE_VM).  But if sigaltstack is set by a
parent thread, and then if multiple cloned child threads (+ parent threads)
call signal handler at the same time, some threads may be conflicted -
because they share to use the same alternative signal stack region.
Finally they get sigsegv.  It's an undesirable race condition.  Note that
child threads created from NPTL pthread_create() also hit this conflict
when the parent thread uses sigaltstack, without my patch.

To fix this problem, this patch clears the child threads' sigaltstack
information like exec().  This behavior follows the SUSv3 specification.
In SUSv3, pthread_create() says "The alternate stack shall not be inherited
(when new threads are initialized)".  It means that sigaltstack should be
cleared when sigaltstack memory space is shared by cloned threads with
CLONE_SIGHAND.

Note that I chose "if (clone_flags & CLONE_SIGHAND)" line because:
  - If clone_flags line is not existed, fork() does not inherit sigaltstack.
  - CLONE_VM is another choice, but vfork() does not inherit sigaltstack.
  - CLONE_SIGHAND implies CLONE_VM, and it looks suitable.
  - CLONE_THREAD is another candidate, and includes CLONE_SIGHAND + CLONE_VM,
    but this flag has a bit different semantics.
I decided to use CLONE_SIGHAND.

[ Changed to test for CLONE_VM && !CLONE_VFORK after discussion --Linus ]

Signed-off-by: GOTO Masanori 
Cc: Roland McGrath 
Cc: Ingo Molnar 
Acked-by: Linus Torvalds 
Cc: Ulrich Drepper 
Cc: Jakub Jelinek 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] remove __put_task_struct_cb export again

2006-03-11T17:19:34+00:00

The patch '[PATCH] RCU signal handling' [1] added an export for
__put_task_struct_cb, a put_task_struct helper newly introduced in that
patch.  But the put_task_struct couldn't be used modular previously as
__put_task_struct wasn't exported.  There are not callers of it in modular
code, and it shouldn't be exported because we don't want drivers to hold
references to task_structs.

This patch removes the export and folds __put_task_struct into
__put_task_struct_cb as there's no other caller.

[1] http://www2.kernel.org/git/gitweb.cgi?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e56d090310d7625ecb43a1eeebd479f04affb48b

Signed-off-by: Christoph Hellwig 
Acked-by: Paul E. McKenney 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds