linux-toradex.git/fs/proc, branch v2.6.32.28

mm: Move vma_stack_continue into mm.h

2010-10-29T04:44:18+00:00

commit 39aa3cb3e8250db9188a6f1e3fb62ffa1a717678 upstream.

So it can be used by all that need to check for that.

Signed-off-by: Stefan Bader 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm: fix up some user-visible effects of the stack guard page

2010-08-20T18:34:24+00:00

commit d7824370e26325c881b665350ce64fb0a4fde24a upstream.

This commit makes the stack guard page somewhat less visible to user
space. It does this by:

 - not showing the guard page in /proc//maps

   It looks like lvm-tools will actually read /proc/self/maps to figure
   out where all its mappings are, and effectively do a specialized
   "mlockall()" in user space.  By not showing the guard page as part of
   the mapping (by just adding PAGE_SIZE to the start for grows-up
   pages), lvm-tools ends up not being aware of it.

 - by also teaching the _real_ mlock() functionality not to try to lock
   the guard page.

   That would just expand the mapping down to create a new guard page,
   so there really is no point in trying to lock it in place.

It would perhaps be nice to show the guard page specially in
/proc//maps (or at least mark grow-down segments some way), but
let's not open ourselves up to more breakage by user space from programs
that depends on the exact deails of the 'maps' file.

Special thanks to Henrique de Moraes Holschuh for diving into lvm-tools
source code to see what was going on with the whole new warning.

Reported-and-tested-by: François Valenduc 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

sched, cputime: Introduce thread_group_times()

2010-08-13T20:20:14+00:00

commit 0cf55e1ec08bb5a22e068309e2d8ba1180ab4239 upstream.

This is a real fix for problem of utime/stime values decreasing
described in the thread:

   http://lkml.org/lkml/2009/11/3/522

Now cputime is accounted in the following way:

 - {u,s}time in task_struct are increased every time when the thread
   is interrupted by a tick (timer interrupt).

 - When a thread exits, its {u,s}time are added to signal->{u,s}time,
   after adjusted by task_times().

 - When all threads in a thread_group exits, accumulated {u,s}time
   (and also c{u,s}time) in signal struct are added to c{u,s}time
   in signal struct of the group's parent.

So {u,s}time in task struct are "raw" tick count, while
{u,s}time and c{u,s}time in signal struct are "adjusted" values.

And accounted values are used by:

 - task_times(), to get cputime of a thread:
   This function returns adjusted values that originates from raw
   {u,s}time and scaled by sum_exec_runtime that accounted by CFS.

 - thread_group_cputime(), to get cputime of a thread group:
   This function returns sum of all {u,s}time of living threads in
   the group, plus {u,s}time in the signal struct that is sum of
   adjusted cputimes of all exited threads belonged to the group.

The problem is the return value of thread_group_cputime(),
because it is mixed sum of "raw" value and "adjusted" value:

  group's {u,s}time = foreach(thread){{u,s}time} + exited({u,s}time)

This misbehavior can break {u,s}time monotonicity.
Assume that if there is a thread that have raw values greater
than adjusted values (e.g. interrupted by 1000Hz ticks 50 times
but only runs 45ms) and if it exits, cputime will decrease (e.g.
-5ms).

To fix this, we could do:

  group's {u,s}time = foreach(t){task_times(t)} + exited({u,s}time)

But task_times() contains hard divisions, so applying it for
every thread should be avoided.

This patch fixes the above problem in the following way:

 - Modify thread's exit (= __exit_signal()) not to use task_times().
   It means {u,s}time in signal struct accumulates raw values instead
   of adjusted values.  As the result it makes thread_group_cputime()
   to return pure sum of "raw" values.

 - Introduce a new function thread_group_times(*task, *utime, *stime)
   that converts "raw" values of thread_group_cputime() to "adjusted"
   values, in same calculation procedure as task_times().

 - Modify group's exit (= wait_task_zombie()) to use this introduced
   thread_group_times().  It make c{u,s}time in signal struct to
   have adjusted values like before this patch.

 - Replace some thread_group_cputime() by thread_group_times().
   This replacements are only applied where conveys the "adjusted"
   cputime to users, and where already uses task_times() near by it.
   (i.e. sys_times(), getrusage(), and /proc//stat.)

This patch have a positive side effect:

 - Before this patch, if a group contains many short-life threads
   (e.g. runs 0.9ms and not interrupted by ticks), the group's
   cputime could be invisible since thread's cputime was accumulated
   after adjusted: imagine adjustment function as adj(ticks, runtime),
     {adj(0, 0.9) + adj(0, 0.9) + ....} = {0 + 0 + ....} = 0.
   After this patch it will not happen because the adjustment is
   applied after accumulated.

v2:
 - remove if()s, put new variables into signal_struct.

Signed-off-by: Hidetoshi Seto 
Acked-by: Peter Zijlstra 
Cc: Spencer Candland 
Cc: Americo Wang 
Cc: Oleg Nesterov 
Cc: Balbir Singh 
Cc: Stanislaw Gruszka 
LKML-Reference: <4B162517.8040909@jp.fujitsu.com>
Signed-off-by: Ingo Molnar 
Signed-off-by: Jiri Slaby 
Signed-off-by: Greg Kroah-Hartman

revert "procfs: provide stack information for threads" and its fixup commits

2010-05-26T21:29:19+00:00

commit 34441427aab4bdb3069a4ffcda69a99357abcb2e upstream.

Originally, commit d899bf7b ("procfs: provide stack information for
threads") attempted to introduce a new feature for showing where the
threadstack was located and how many pages are being utilized by the
stack.

Commit c44972f1 ("procfs: disable per-task stack usage on NOMMU") was
applied to fix the NO_MMU case.

Commit 89240ba0 ("x86, fs: Fix x86 procfs stack information for threads on
64-bit") was applied to fix a bug in ia32 executables being loaded.

Commit 9ebd4eba7 ("procfs: fix /proc//stat stack pointer for kernel
threads") was applied to fix a bug which had kernel threads printing a
userland stack address.

Commit 1306d603f ('proc: partially revert "procfs: provide stack
information for threads"') was then applied to revert the stack pages
being used to solve a significant performance regression.

This patch nearly undoes the effect of all these patches.

The reason for reverting these is it provides an unusable value in
field 28.  For x86_64, a fork will result in the task->stack_start
value being updated to the current user top of stack and not the stack
start address.  This unpredictability of the stack_start value makes
it worthless.  That includes the intended use of showing how much stack
space a thread has.

Other architectures will get different values.  As an example, ia64
gets 0.  The do_fork() and copy_process() functions appear to treat the
stack_start and stack_size parameters as architecture specific.

I only partially reverted c44972f1 ("procfs: disable per-task stack usage
on NOMMU") .  If I had completely reverted it, I would have had to change
mm/Makefile only build pagewalk.o when CONFIG_PROC_PAGE_MONITOR is
configured.  Since I could not test the builds without significant effort,
I decided to not change mm/Makefile.

I only partially reverted 89240ba0 ("x86, fs: Fix x86 procfs stack
information for threads on 64-bit") .  I left the KSTK_ESP() change in
place as that seemed worthwhile.

Signed-off-by: Robin Holt 
Cc: Stefani Seibold 
Cc: KOSAKI Motohiro 
Cc: Michal Simek 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

proc: partially revert "procfs: provide stack information for threads"

2010-05-26T21:29:19+00:00

commit 1306d603fcf1f6682f8575d1ff23631a24184b21 upstream.

Commit d899bf7b (procfs: provide stack information for threads) introduced
to show stack information in /proc/{pid}/status.  But it cause large
performance regression.  Unfortunately /proc/{pid}/status is used ps
command too and ps is one of most important component.  Because both to
take mmap_sem and page table walk are heavily operation.

If many process run, the ps performance is,

[before d899bf7b]

% perf stat ps >/dev/null

 Performance counter stats for 'ps':

     4090.435806  task-clock-msecs         #      0.032 CPUs
             229  context-switches         #      0.000 M/sec
               0  CPU-migrations           #      0.000 M/sec
             234  page-faults              #      0.000 M/sec
      8587565207  cycles                   #   2099.425 M/sec
      9866662403  instructions             #      1.149 IPC
      3789415411  cache-references         #    926.409 M/sec
        30419509  cache-misses             #      7.437 M/sec

   128.859521955  seconds time elapsed

[after d899bf7b]

% perf stat  ps  > /dev/null

 Performance counter stats for 'ps':

     4305.081146  task-clock-msecs         #      0.028 CPUs
             480  context-switches         #      0.000 M/sec
               2  CPU-migrations           #      0.000 M/sec
             237  page-faults              #      0.000 M/sec
      9021211334  cycles                   #   2095.480 M/sec
     10605887536  instructions             #      1.176 IPC
      3612650999  cache-references         #    839.160 M/sec
        23917502  cache-misses             #      5.556 M/sec

   152.277819582  seconds time elapsed

Thus, this patch revert it. Fortunately /proc/{pid}/task/{tid}/smaps
provide almost same information. we can use it.

Commit d899bf7b introduced two features:

 1) Add the annotattion of [thread stack: xxxx] mark to
    /proc/{pid}/task/{tid}/maps.
 2) Add StackUsage field to /proc/{pid}/status.

I only revert (2), because I haven't seen (1) cause regression.

Signed-off-by: KOSAKI Motohiro 
Cc: Stefani Seibold 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Alexey Dobriyan 
Cc: "Eric W. Biederman" 
Cc: Randy Dunlap 
Cc: Andrew Morton 
Cc: Andi Kleen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

procfs: fix tid fdinfo

2010-05-12T21:57:03+00:00

commit 3835541dd481091c4dbf5ef83c08aed12e50fd61 upstream.

Correct the file_operations struct in fdinfo entry of tid_base_stuff[].

Presently /proc/*/task/*/fdinfo contains symlinks to opened files like
/proc/*/fd/.

Signed-off-by: Jerome Marchand 
Cc: Alexander Viro 
Cc: Miklos Szeredi 
Cc: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

oom: fix the unsafe usage of badness() in proc_oom_score()

2010-04-26T14:41:13+00:00

commit b95c35e76b29ba812e5dabdd91592e25ec640e93 upstream.

proc_oom_score(task) has a reference to task_struct, but that is all.
If this task was already released before we take tasklist_lock

	- we can't use task->group_leader, it points to nowhere

	- it is not safe to call badness() even if this task is
	  ->group_leader, has_intersects_mems_allowed() assumes
	  it is safe to iterate over ->thread_group list.

	- even worse, badness() can hit ->signal == NULL

Add the pid_alive() check to ensure __unhash_process() was not called.

Also, use "task" instead of task->group_leader. badness() should return
the same result for any sub-thread. Currently this is not true, but
this should be changed anyway.

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

Switch proc/self to nd_set_link()

2010-03-15T15:49:37+00:00

commit 7fee4868be91e71a3ee8e57289ebf5e10a12297e upstream.

Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

procfs: fix /proc//stat stack pointer for kernel threads

2009-11-18T01:40:33+00:00

Fix a small issue for the stack pointer in /proc//stat.  In case of a
kernel thread the value of the printed stack pointer should be 0.

Signed-off-by: Stefani Seibold 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

pidns: fix a leak in /proc dentries and inodes with pid namespaces.

2009-11-12T15:25:57+00:00

Daniel Lezcano reported a leak in 'struct pid' and 'struct pid_namespace'
that is discussed in:

	http://lkml.org/lkml/2009/10/2/159.

To summarize the thread, when container-init is terminated, it sets the
PF_EXITING flag, zaps other processes in the container and waits to reap
them.  As a part of reaping, the container-init should flush any /proc
dentries associated with the processes.  But because the container-init is
itself exiting and the following PF_EXITING check, the dentries are not
flushed, resulting in leak in /proc inodes and dentries.

This fix reverts the commit 7766755a2f249e7e0 ("Fix /proc dcache deadlock
in do_exit") which introduced the check for PF_EXITING.  At the time of
the commit, shrink_dcache_parent() flushed dentries from other filesystems
also and could have caused a deadlock which the commit fixed.  But as
pointed out by Eric Biederman, after commit 0feae5c47aabdde59,
shrink_dcache_parent() no longer affects other filesystems.  So reverting
the commit is now safe.

As pointed out by Jan Kara, the leak is not as critical since the
unclaimed space will be reclaimed under memory pressure or by:

	echo 3 > /proc/sys/vm/drop_caches

But since this check is no longer required, its best to remove it.

Signed-off-by: Sukadev Bhattiprolu 
Reported-by: Daniel Lezcano 
Acked-by: Eric W. Biederman 
Acked-by: Jan Kara 
Cc: Andrea Arcangeli 
Cc: Serge Hallyn 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds