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  1. 14 10月, 2008 1 次提交
    • M
      tracing, sched: LTTng instrumentation - scheduler · 0a16b607
      由 Mathieu Desnoyers 提交于 
      Instrument the scheduler activity (sched_switch, migration, wakeups,
wait for a task, signal delivery) and process/thread
creation/destruction (fork, exit, kthread stop). Actually, kthread
creation is not instrumented in this patch because it is architecture
dependent. It allows to connect tracers such as ftrace which detects
scheduling latencies, good/bad scheduler decisions. Tools like LTTng can
export this scheduler information along with instrumentation of the rest
of the kernel activity to perform post-mortem analysis on the scheduler
activity.

About the performance impact of tracepoints (which is comparable to
markers), even without immediate values optimizations, tests done by
Hideo Aoki on ia64 show no regression. His test case was using hackbench
on a kernel where scheduler instrumentation (about 5 events in code
scheduler code) was added. See the "Tracepoints" patch header for
performance result detail.

Changelog :

- Change instrumentation location and parameter to match ftrace
  instrumentation, previously done with kernel markers.

[ mingo@elte.hu: conflict resolutions ]
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: N'Peter Zijlstra' <peterz@infradead.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      0a16b607
  3. 29 9月, 2008 1 次提交
    • B
      mm owner: fix race between swapoff and exit · 31a78f23
      由 Balbir Singh 提交于 
      There's a race between mm->owner assignment and swapoff, more easily
seen when task slab poisoning is turned on.  The condition occurs when
try_to_unuse() runs in parallel with an exiting task.  A similar race
can occur with callers of get_task_mm(), such as /proc/<pid>/<mmstats>
or ptrace or page migration.

CPU0                                    CPU1
                                        try_to_unuse
                                        looks at mm = task0->mm
                                        increments mm->mm_users
task 0 exits
mm->owner needs to be updated, but no
new owner is found (mm_users > 1, but
no other task has task->mm = task0->mm)
mm_update_next_owner() leaves
                                        mmput(mm) decrements mm->mm_users
task0 freed
                                        dereferencing mm->owner fails

The fix is to notify the subsystem via mm_owner_changed callback(),
if no new owner is found, by specifying the new task as NULL.

Jiri Slaby:
mm->owner was set to NULL prior to calling cgroup_mm_owner_callbacks(), but
must be set after that, so as not to pass NULL as old owner causing oops.

Daisuke Nishimura:
mm_update_next_owner() may set mm->owner to NULL, but mem_cgroup_from_task()
and its callers need to take account of this situation to avoid oops.

Hugh Dickins:
Lockdep warning and hang below exec_mmap() when testing these patches.
exit_mm() up_reads mmap_sem before calling mm_update_next_owner(),
so exec_mmap() now needs to do the same.  And with that repositioning,
there's now no point in mm_need_new_owner() allowing for NULL mm.
Reported-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NBalbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: NJiri Slaby <jirislaby@gmail.com>
Signed-off-by: NDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      31a78f23
  5. 06 9月, 2008 1 次提交
    • B
      sched: fix process time monotonicity · 49048622
      由 Balbir Singh 提交于 
      Spencer reported a problem where utime and stime were going negative despite
the fixes in commit b27f03d4. The suspected
reason for the problem is that signal_struct maintains it's own utime and
stime (of exited tasks), these are not updated using the new task_utime()
routine, hence sig->utime can go backwards and cause the same problem
to occur (sig->utime, adds tsk->utime and not task_utime()). This patch
fixes the problem

TODO: using max(task->prev_utime, derived utime) works for now, but a more
generic solution is to implement cputime_max() and use the cputime_gt()
function for comparison.

Reported-by: spencer@bluehost.com
Signed-off-by: NBalbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      49048622
  7. 03 9月, 2008 1 次提交
  9. 27 8月, 2008 1 次提交
  11. 02 8月, 2008 1 次提交
  13. 28 7月, 2008 1 次提交
    • A
      task IO accounting: improve code readability · 5995477a
      由 Andrea Righi 提交于 
      Put all i/o statistics in struct proc_io_accounting and use inline functions to
initialize and increment statistics, removing a lot of single variable
assignments.

This also reduces the kernel size as following (with CONFIG_TASK_XACCT=y and
CONFIG_TASK_IO_ACCOUNTING=y).

    text    data     bss     dec     hex filename
   11651       0       0   11651    2d83 kernel/exit.o.before
   11619       0       0   11619    2d63 kernel/exit.o.after
   10886     132     136   11154    2b92 kernel/fork.o.before
   10758     132     136   11026    2b12 kernel/fork.o.after

 3082029  807968 4818600 8708597  84e1f5 vmlinux.o.before
 3081869  807968 4818600 8708437  84e155 vmlinux.o.after
Signed-off-by: NAndrea Righi <righi.andrea@gmail.com>
Acked-by: NOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      5995477a
  15. 27 7月, 2008 4 次提交
  17. 26 7月, 2008 8 次提交
  19. 17 7月, 2008 4 次提交
    • R
      fix dangling zombie when new parent ignores children · 666f164f
      由 Roland McGrath 提交于 
      This fixes an arcane bug that we think was a regression introduced
by commit b2b2cbc4.  When a parent
ignores SIGCHLD (or uses SA_NOCLDWAIT), its children would self-reap
but they don't if it's using ptrace on them.  When the parent thread
later exits and ceases to ptrace a child but leaves other live
threads in the parent's thread group, any zombie children are left
dangling.  The fix makes them self-reap then, as they would have
done earlier if ptrace had not been in use.
Signed-off-by: NRoland McGrath <roland@redhat.com>
      666f164f
    • R
      do_wait: return security_task_wait() error code in place of -ECHILD · 14dd0b81
      由 Roland McGrath 提交于 
      This reverts the effect of commit f2cc3eb1
"do_wait: fix security checks".  That change reverted the effect of commit
73243284.  The rationale for the original
commit still stands.  The inconsistent treatment of children hidden by
ptrace was an unintended omission in the original change and in no way
invalidates its purpose.

This makes do_wait return the error returned by security_task_wait()
(usually -EACCES) in place of -ECHILD when there are some children the
caller would be able to wait for if not for the permission failure.  A
permission error will give the user a clue to look for security policy
problems, rather than for mysterious wait bugs.
Signed-off-by: NRoland McGrath <roland@redhat.com>
      14dd0b81
    • R
      ptrace children revamp · f470021a
      由 Roland McGrath 提交于 
      ptrace no longer fiddles with the children/sibling links, and the
old ptrace_children list is gone.  Now ptrace, whether of one's own
children or another's via PTRACE_ATTACH, just uses the new ptraced
list instead.

There should be no user-visible difference that matters.  The only
change is the order in which do_wait() sees multiple stopped
children and stopped ptrace attachees.  Since wait_task_stopped()
was changed earlier so it no longer reorders the children list, we
already know this won't cause any new problems.
Signed-off-by: NRoland McGrath <roland@redhat.com>
      f470021a
    • R
      do_wait reorganization · 98abed02
      由 Roland McGrath 提交于 
      This breaks out the guts of do_wait into three subfunctions.
The control flow is less nonobvious without so much goto.
do_wait_thread and ptrace_do_wait contain the main work of the outer loop.
wait_consider_task contains the main work of the inner loop.
Signed-off-by: NRoland McGrath <roland@redhat.com>
      98abed02
  21. 03 7月, 2008 1 次提交
  23. 25 5月, 2008 1 次提交
  25. 02 5月, 2008 1 次提交
  27. 30 4月, 2008 6 次提交
  29. 29 4月, 2008 1 次提交
    • B
      cgroups: add an owner to the mm_struct · cf475ad2
      由 Balbir Singh 提交于 
      Remove the mem_cgroup member from mm_struct and instead adds an owner.

This approach was suggested by Paul Menage.  The advantage of this approach
is that, once the mm->owner is known, using the subsystem id, the cgroup
can be determined.  It also allows several control groups that are
virtually grouped by mm_struct, to exist independent of the memory
controller i.e., without adding mem_cgroup's for each controller, to
mm_struct.

A new config option CONFIG_MM_OWNER is added and the memory resource
controller selects this config option.

This patch also adds cgroup callbacks to notify subsystems when mm->owner
changes.  The mm_cgroup_changed callback is called with the task_lock() of
the new task held and is called just prior to changing the mm->owner.

I am indebted to Paul Menage for the several reviews of this patchset and
helping me make it lighter and simpler.

This patch was tested on a powerpc box, it was compiled with both the
MM_OWNER config turned on and off.

After the thread group leader exits, it's moved to init_css_state by
cgroup_exit(), thus all future charges from runnings threads would be
redirected to the init_css_set's subsystem.
Signed-off-by: NBalbir Singh <balbir@linux.vnet.ibm.com>
Cc: Pavel Emelianov <xemul@openvz.org>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Sudhir Kumar <skumar@linux.vnet.ibm.com>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Cc: Hirokazu Takahashi <taka@valinux.co.jp>
Cc: David Rientjes <rientjes@google.com>,
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: NPekka Enberg <penberg@cs.helsinki.fi>
Reviewed-by: NPaul Menage <menage@google.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      cf475ad2
  31. 28 4月, 2008 1 次提交
    • L
      mempolicy: rename mpol_free to mpol_put · f0be3d32
      由 Lee Schermerhorn 提交于 
      This is a change that was requested some time ago by Mel Gorman.  Makes sense
to me, so here it is.

Note: I retain the name "mpol_free_shared_policy()" because it actually does
free the shared_policy, which is NOT a reference counted object.  However, ...

The mempolicy object[s] referenced by the shared_policy are reference counted,
so mpol_put() is used to release the reference held by the shared_policy.  The
mempolicy might not be freed at this time, because some task attached to the
shared object associated with the shared policy may be in the process of
allocating a page based on the mempolicy.  In that case, the task performing
the allocation will hold a reference on the mempolicy, obtained via
mpol_shared_policy_lookup().  The mempolicy will be freed when all tasks
holding such a reference have called mpol_put() for the mempolicy.
Signed-off-by: NLee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      f0be3d32
  33. 25 4月, 2008 2 次提交
    • A
      [PATCH] sanitize unshare_files/reset_files_struct · 3b125388
      由 Al Viro 提交于 
      * let unshare_files() give caller the displaced files_struct
* don't bother with grabbing reference only to drop it in the
  caller if it hadn't been shared in the first place
* in that form unshare_files() is trivially implemented via
  unshare_fd(), so we eliminate the duplicate logics in fork.c
* reset_files_struct() is not just only called for current;
  it will break the system if somebody ever calls it for anything
  else (we can't modify ->files of somebody else).  Lose the
  task_struct * argument.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      3b125388
    • A
      [PATCH] sanitize handling of shared descriptor tables in failing execve() · fd8328be
      由 Al Viro 提交于 
      * unshare_files() can fail; doing it after irreversible actions is wrong
  and de_thread() is certainly irreversible.
* since we do it unconditionally anyway, we might as well do it in do_execve()
  and save ourselves the PITA in binfmt handlers, etc.
* while we are at it, binfmt_som actually leaked files_struct on failure.

As a side benefit, unshare_files(), put_files_struct() and reset_files_struct()
become unexported.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      fd8328be
  35. 23 4月, 2008 1 次提交
  37. 11 4月, 2008 1 次提交
    • R
      asmlinkage_protect replaces prevent_tail_call · 54a01510
      由 Roland McGrath 提交于 
      The prevent_tail_call() macro works around the problem of the compiler
clobbering argument words on the stack, which for asmlinkage functions
is the caller's (user's) struct pt_regs.  The tail/sibling-call
optimization is not the only way that the compiler can decide to use
stack argument words as scratch space, which we have to prevent.
Other optimizations can do it too.

Until we have new compiler support to make "asmlinkage" binding on the
compiler's own use of the stack argument frame, we have work around all
the manifestations of this issue that crop up.

More cases seem to be prevented by also keeping the incoming argument
variables live at the end of the function.  This makes their original
stack slots attractive places to leave those variables, so the compiler
tends not clobber them for something else.  It's still no guarantee, but
it handles some observed cases that prevent_tail_call() did not.
Signed-off-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      54a01510
  39. 09 3月, 2008 1 次提交
  41. 04 3月, 2008 1 次提交
    • O
      exit_notify: fix kill_orphaned_pgrp() usage with mt exit · 821c7de7
      由 Oleg Nesterov 提交于 
      1. exit_notify() always calls kill_orphaned_pgrp(). This is wrong, we
   should do this only when the whole process exits.

2. exit_notify() uses "current" as "ignored_task", obviously wrong.
   Use ->group_leader instead.

Test case:

	void hup(int sig)
	{
		printf("HUP received\n");
	}

	void *tfunc(void *arg)
	{
		sleep(2);
		printf("sub-thread exited\n");
		return NULL;
	}

	int main(int argc, char *argv[])
	{
		if (!fork()) {
			signal(SIGHUP, hup);
			kill(getpid(), SIGSTOP);
			exit(0);
		}

		pthread_t thr;
		pthread_create(&thr, NULL, tfunc, NULL);

		sleep(1);
		printf("main thread exited\n");
		syscall(__NR_exit, 0);

		return 0;
	}

output:

	main thread exited
	HUP received
	Hangup

With this patch the output is:

	main thread exited
	sub-thread exited
	HUP received
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      821c7de7