linux.git/fs/proc, branch v3.14-rc2

fs/proc/array.c: change do_task_stat() to use while_each_thread()

2014-01-24T00:37:02+00:00

Change the remaining next_thread (ab)users to use while_each_thread().

The last user which should be changed is next_tid(), but we can't do this
now.

__exit_signal() and complete_signal() are fine, they actually need
next_thread() logic.

This patch (of 3):

do_task_stat() can use while_each_thread(), no changes in
the compiled code.

Signed-off-by: Oleg Nesterov 
Cc: KOSAKI Motohiro 
Cc: Al Viro 
Cc: Kees Cook 
Reviewed-by: Sameer Nanda 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs/proc: don't use module_init for non-modular core code

2014-01-24T00:37:02+00:00

PROC_FS is a bool, so this code is either present or absent.  It will
never be modular, so using module_init as an alias for __initcall is
rather misleading.

Fix this up now, so that we can relocate module_init from init.h into
module.h in the future.  If we don't do this, we'd have to add module.h to
obviously non-modular code, and that would be ugly at best.

Note that direct use of __initcall is discouraged, vs.  one of the
priority categorized subgroups.  As __initcall gets mapped onto
device_initcall, our use of fs_initcall (which makes sense for fs code)
will thus change these registrations from level 6-device to level 5-fs
(i.e.  slightly earlier).  However no observable impact of that small
difference has been observed during testing, or is expected.

Also note that this change uncovers a missing semicolon bug in the
registration of vmcore_init as an initcall.

Signed-off-by: Paul Gortmaker 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs/proc/proc_devtree.c: remove empty /proc/device-tree when no openfirmware exists.

2014-01-24T00:37:01+00:00

Distribution kernels might want to build in support for /proc/device-tree
for kernels that might end up running on hardware that doesn't support
openfirmware.  This results in an empty /proc/device-tree existing.
Remove it if the OFW root node doesn't exist.

This situation actually confuses grub2, resulting in install failures.
grub2 sees the /proc/device-tree and picks the wrong install target cf.
http://bzr.savannah.gnu.org/lh/grub/trunk/grub/annotate/4300/util/grub-install.in#L311
grub should be more robust, but still, leaving an empty proc dir seems
pointless.

Addresses https://bugzilla.redhat.com/show_bug.cgi?id=818378.

Signed-off-by: Dave Jones 
Cc: Al Viro 
Cc: Paul Mackerras 
Cc: Josh Boyer 
Cc: Benjamin Herrenschmidt 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: set attributes of pde using accessor functions

2014-01-24T00:37:01+00:00

Use existing accessors proc_set_user() and proc_set_size() to set
attributes.  Just a cleanup.

Signed-off-by: Rui Xiang 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: fix ->f_pos overflows in first_tid()

2014-01-24T00:37:01+00:00

1. proc_task_readdir()->first_tid() path truncates f_pos to int, this
   is wrong even on 64bit.

   We could check that f_pos < PID_MAX or even INT_MAX in
   proc_task_readdir(), but this patch simply checks the potential
   overflow in first_tid(), this check is nop on 64bit.  We do not care if
   it was negative and the new unsigned value is huge, all we need to
   ensure is that we never wrongly return !NULL.

2. Remove the 2nd "nr != 0" check before get_nr_threads(),
   nr_threads == 0 is not distinguishable from !pid_task() above.

Signed-off-by: Oleg Nesterov 
Cc: "Eric W. Biederman" 
Cc: Michal Hocko 
Cc: Sameer Nanda 
Cc: Sergey Dyasly 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: don't (ab)use ->group_leader in proc_task_readdir() paths

2014-01-24T00:37:01+00:00

proc_task_readdir() does not really need "leader", first_tid() has to
revalidate it anyway.  Just pass proc_pid(inode) to first_tid() instead,
it can do pid_task(PIDTYPE_PID) itself and read ->group_leader only if
necessary.

The patch also extracts the "inode is dead" code from
pid_delete_dentry(dentry) into the new trivial helper,
proc_inode_is_dead(inode), proc_task_readdir() uses it to return -ENOENT
if this dir was removed.

This is a bit racy, but the race is very inlikely and the getdents() after
openndir() can see the empty "." + ".." dir only once.

Signed-off-by: Oleg Nesterov 
Cc: "Eric W. Biederman" 
Cc: Michal Hocko 
Cc: Sameer Nanda 
Cc: Sergey Dyasly 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: change first_tid() to use while_each_thread() rather than next_thread()

2014-01-24T00:37:01+00:00

Rerwrite the main loop to use while_each_thread() instead of
next_thread().  We are going to fix or replace while_each_thread(),
next_thread() should be avoided whenever possible.

Signed-off-by: Oleg Nesterov 
Cc: "Eric W. Biederman" 
Cc: Michal Hocko 
Cc: Sameer Nanda 
Cc: Sergey Dyasly 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: fix the potential use-after-free in first_tid()

2014-01-24T00:37:01+00:00

proc_task_readdir() verifies that the result of get_proc_task() is
pid_alive() and thus its ->group_leader is fine too.  However this is not
necessarily true after rcu_read_unlock(), we need to recheck this again
after first_tid() does rcu_read_lock().  Otherwise
leader->thread_group.next (used by next_thread()) can be invalid if the
rcu grace period expires in between.

The race is subtle and unlikely, but still it is possible afaics.  To
simplify lets ignore the "likely" case when tid != 0, f_version can be
cleared by proc_task_operations->llseek().

Suppose we have a main thread M and its subthread T.  Suppose that f_pos
== 3, iow first_tid() should return T.  Now suppose that the following
happens between rcu_read_unlock() and rcu_read_lock():

	1. T execs and becomes the new leader. This removes M from
	    ->thread_group but next_thread(M) is still T.

	2. T creates another thread X which does exec as well, T
	   goes away.

	3. X creates another subthread, this increments nr_threads.

	4. first_tid() does next_thread(M) and returns the already
	   dead T.

Note also that we need 2.  and 3.  only because of get_nr_threads() check,
and this check was supposed to be optimization only.

Signed-off-by: Oleg Nesterov 
Cc: "Eric W. Biederman" 
Cc: Michal Hocko 
Cc: Sameer Nanda 
Cc: Sergey Dyasly 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: cleanup/simplify get_task_state/task_state_array

2014-01-24T00:37:01+00:00

get_task_state() and task_state_array[] look confusing and suboptimal, it
is not clear what it can actually report to user-space and
task_state_array[] blows .data for no reason.

1. state = (tsk->state & TASK_REPORT) | tsk->exit_state is not
   clear. TASK_REPORT is self-documenting but it is not clear
   what ->exit_state can add.

   Move the potential exit_state's (EXIT_ZOMBIE and EXIT_DEAD)
   into TASK_REPORT and use it to calculate the final result.

2. With the change above it is obvious that task_state_array[]
   has the unused entries just to make BUILD_BUG_ON() happy.

   Change this BUILD_BUG_ON() to use TASK_REPORT rather than
   TASK_STATE_MAX and shrink task_state_array[].

3. Turn the "while (state)" loop into fls(state).

Signed-off-by: Oleg Nesterov 
Cc: Peter Zijlstra 
Cc: David Laight 
Cc: Geert Uytterhoeven 
Cc: Ingo Molnar 
Cc: Tejun Heo 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs/proc/page.c: add PageAnon check to surely detect thp

2014-01-24T00:36:50+00:00

stable_page_flags() checks !PageHuge && PageTransCompound && PageLRU to
know that a specified page is thp or not.  But sometimes it's not enough
and we fail to detect thp when the thp is on pagevec.  This happens only
for a few seconds after LRU list operations, but it makes it difficult
to control our applications depending on this flag.

So this patch adds another check PageAnon to detect thps on pagevec.  It
might not give the future extensibility for thp pagecache, but it's OK
at least for now.

Signed-off-by: Naoya Horiguchi 
Cc: David Rientjes 
Cc: KOSAKI Motohiro 
Cc: Wu Fengguang 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds