The kernel implements readlink of /proc/pid/exe by getting the file from
the first executable VMA. Then the path to the file is reconstructed and
reported as the result.
Because of the VMA walk the code is slightly different on nommu systems.
This patch avoids separate /proc/pid/exe code on nommu systems. Instead of
walking the VMAs to find the first executable file-backed VMA we store a
reference to the exec'd file in the mm_struct.
That reference would prevent the filesystem holding the executable file
from being unmounted even after unmapping the VMAs. So we track the number
of VM_EXECUTABLE VMAs and drop the new reference when the last one is
unmapped. This avoids pinning the mounted filesystem.
[akpm@linux-foundation.org: improve comments]
[yamamoto@valinux.co.jp: fix dup_mmap]
Signed-off-by: Matt Helsley <matthltc@us.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: David Howells <dhowells@redhat.com>
Cc:"Eric W. Biederman" <ebiederm@xmission.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[mszeredi@suse.cz] rewrite and split big patch into managable chunks
/proc/mounts in its current form lacks important information:
- propagation state
- root of mount for bind mounts
- the st_dev value used within the filesystem
- identifier for each mount and it's parent
It also suffers from the following problems:
- not easily extendable
- ambiguity of mountpoints within a chrooted environment
- doesn't distinguish between filesystem dependent and independent options
- doesn't distinguish between per mount and per super block options
This patch introduces /proc/<pid>/mountinfo which attempts to address
all these deficiencies.
Code shared between /proc/<pid>/mounts and /proc/<pid>/mountinfo is
extracted into separate functions.
Thanks to Al Viro for the help in getting the design right.
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Allow /proc/<pid>/mountinfo to use the root of <pid> to calculate
mountpoints.
- move definition of 'struct proc_mounts' to <linux/mnt_namespace.h>
- add the process's namespace and root to this structure
- pass a pointer to 'struct proc_mounts' into seq_operations
In addition the following cleanups are made:
- use a common open function for /proc/<pid>/{mounts,mountstat}
- surround namespace.c part of these proc files with #ifdef CONFIG_PROC_FS
- make the seq_operations structures const
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Since we drop the rcu_read_lock inside the loop, we can't assume
that files->fdt will remain unchanged (and not freed) between
iterations.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
commit e9720ac ([NET]: Make /proc/net a symlink on /proc/self/net (v3))
broke ganglia and probably other applications that read /proc/net/dev.
This is due to the change of permissions of /proc/net that was
introduced in that commit.
Before: dr-xr-xr-x 5 root root 0 Mar 19 11:30 /proc/net
After: dr-xr--r-- 5 root root 0 Mar 19 11:29 /proc/self/net
This patch restores the permissions to the old value which makes
ganglia happy again.
Pavel Emelyanov says:
This also broke the postfix, as it was reported in bug #10286
and described in detail by Benjamin.
Signed-off-by: Andre Noll <maan@systemlinux.org>
Acked-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (47 commits)
[SCTP]: Fix local_addr deletions during list traversals.
net: fix build with CONFIG_NET=n
[TCP]: Prevent sending past receiver window with TSO (at last skb)
rt2x00: Add new D-Link USB ID
rt2x00: never disable multicast because it disables broadcast too
libertas: fix the 'compare command with itself' properly
drivers/net/Kconfig: fix whitespace for GELIC_WIRELESS entry
[NETFILTER]: nf_queue: don't return error when unregistering a non-existant handler
[NETFILTER]: nfnetlink_queue: fix EPERM when binding/unbinding and instance 0 exists
[NETFILTER]: nfnetlink_log: fix EPERM when binding/unbinding and instance 0 exists
[NETFILTER]: nf_conntrack: replace horrible hack with ksize()
[NETFILTER]: nf_conntrack: add \n to "expectation table full" message
[NETFILTER]: xt_time: fix failure to match on Sundays
[NETFILTER]: nfnetlink_log: fix computation of netlink skb size
[NETFILTER]: nfnetlink_queue: fix computation of allocated size for netlink skb.
[NETFILTER]: nfnetlink: fix ifdef in nfnetlink_compat.h
[NET]: include <linux/types.h> into linux/ethtool.h for __u* typedef
[NET]: Make /proc/net a symlink on /proc/self/net (v3)
RxRPC: fix rxrpc_recvmsg()'s returning of msg_name
net/enc28j60: oops fix
...
fs/built-in.o:(.rodata+0x1134): undefined reference to `proc_net_inode_operations'
fs/built-in.o:(.rodata+0x1138): undefined reference to `proc_net_operations'
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Current /proc/net is done with so called "shadows", but current
implementation is broken and has little chances to get fixed.
The problem is that dentries subtree of /proc/net directory has
fancy revalidation rules to make processes living in different
net namespaces see different entries in /proc/net subtree, but
currently, tasks see in the /proc/net subdir the contents of any
other namespace, depending on who opened the file first.
The proposed fix is to turn /proc/net into a symlink, which points
to /proc/self/net, which in turn shows what previously was in
/proc/net - the network-related info, from the net namespace the
appropriate task lives in.
# ls -l /proc/net
lrwxrwxrwx 1 root root 8 Mar 5 15:17 /proc/net -> self/net
In other words - this behaves like /proc/mounts, but unlike
"mounts", "net" is not a file, but a directory.
Changes from v2:
* Fixed discrepancy of /proc/net nlink count and selinux labeling
screwup pointed out by Stephen.
To get the correct nlink count the ->getattr callback for /proc/net
is overridden to read one from the net->proc_net entry.
To make selinux still work the net->proc_net entry is initialized
properly, i.e. with the "net" name and the proc_net parent.
Selinux fixes are
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Changes from v1:
* Fixed a task_struct leak in get_proc_task_net, pointed out by Paul.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Change getting task_struct by get_proc_task() at read or write time,
and returns -ESRCH if get_proc_task() returns NULL.
This is same behavior as other /proc files.
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
At lstats_open(), calling get_proc_task() gets task struct, but it never put.
put_task_struct() should be called when releasing.
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reading /proc/<pid>/latency or /proc/<pid>/task/<tid>/latency could cause
NULL pointer dereference.
In lstats_open(), get_proc_task() can return NULL, in which case the kernel
will oops at lstats_show_proc() because m->private is NULL.
When get_proc_task() returns NULL, the kernel should return -ENOENT.
This can be reproduced by the following script.
while :
do
date
bash -c 'ls > ls.$$' &
pid=$!
cat /proc/$pid/latency &
cat /proc/$pid/latency &
cat /proc/$pid/latency &
cat /proc/$pid/latency
done
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
RLIMIT_RTTIME was introduced to allow the user to set a runtime timeout on
real-time tasks: http://lkml.org/lkml/2007/12/18/218. This patch updates
/proc/<pid>/limits with the new rlimit.
Signed-off-by: Eugene Teo <eugeneteo@kernel.sg>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
d_path() is used on a <dentry,vfsmount> pair. Lets use a struct path to
reflect this.
[akpm@linux-foundation.org: fix build in mm/memory.c]
Signed-off-by: Jan Blunck <jblunck@suse.de>
Acked-by: Bryan Wu <bryan.wu@analog.com>
Acked-by: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Neil Brown <neilb@suse.de>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
proc_get_link() is always called with a dentry and a vfsmount from a struct
path. Make proc_get_link() take it directly as an argument.
Signed-off-by: Jan Blunck <jblunck@suse.de>
Acked-by: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Neil Brown <neilb@suse.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Use struct path in fs_struct.
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Jan Blunck <jblunck@suse.de>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Add path_put() functions for releasing a reference to the dentry and
vfsmount of a struct path in the right order
* Switch from path_release(nd) to path_put(&nd->path)
* Rename dput_path() to path_put_conditional()
[akpm@linux-foundation.org: fix cifs]
Signed-off-by: Jan Blunck <jblunck@suse.de>
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: <linux-fsdevel@vger.kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Steven French <sfrench@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is the central patch of a cleanup series. In most cases there is no good
reason why someone would want to use a dentry for itself. This series reflects
that fact and embeds a struct path into nameidata.
Together with the other patches of this series
- it enforced the correct order of getting/releasing the reference count on
<dentry,vfsmount> pairs
- it prepares the VFS for stacking support since it is essential to have a
struct path in every place where the stack can be traversed
- it reduces the overall code size:
without patch series:
text data bss dec hex filename
5321639 858418 715768 6895825 6938d1 vmlinux
with patch series:
text data bss dec hex filename
5320026 858418 715768 6894212 693284 vmlinux
This patch:
Switch from nd->{dentry,mnt} to nd->path.{dentry,mnt} everywhere.
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix cifs]
[akpm@linux-foundation.org: fix smack]
Signed-off-by: Jan Blunck <jblunck@suse.de>
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Revert commit c6caeb7c45 ("proc: fix the
threaded /proc/self"), since Eric says "The patch really is wrong.
There is at least one corner case in procps that cares."
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "Guillaume Chazarain" <guichaz@yahoo.fr>
Cc: "Pavel Emelyanov" <xemul@openvz.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Long ago when the CLONE_THREAD support first went it someone thought it
would be wise to point /proc/self at /proc/<tgid> instead of /proc/<pid>.
Given that /proc/<tgid> can return information about a very different task
(if enough things have been unshared) then our current process /proc/<tgid>
seems blatantly wrong. So far I have yet to think up an example where the
current behavior would be advantageous, and I can see several places where
it is seriously non-intuitive.
We may be stuck with the current broken behavior for backwards
compatibility reasons but lets try fixing our ancient bug for the 2.6.25
time frame and see if anyone screams.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: "Guillaume Chazarain" <guichaz@yahoo.fr>
Cc: "Pavel Emelyanov" <xemul@openvz.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently if you access a /proc that is not mounted with your processes
current pid namespace /proc/self will point at a completely random task.
This patch fixes /proc/self to point to the current process if it is
available in the particular mount of /proc or to return -ENOENT if the
current process is not visible.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently we possibly lookup the pid in the wrong pid namespace. So
seq_file convert proc_pid_status which ensures the proper pid namespaces is
passed in.
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: another build fix]
[akpm@linux-foundation.org: s390 build fix]
[akpm@linux-foundation.org: fix task_name() output]
[akpm@linux-foundation.org: fix nommu build]
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Andrew Morgan <morgan@kernel.org>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This conversion is just for code cleanliness, uniformity, and general safety.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently (as pointed out by Oleg) do_task_stat has a race when calling
task_pid_nr_ns with the task exiting. In addition do_task_stat is not
currently displaying information in the context of the pid namespace that
mounted the /proc filesystem. So "cut -d' ' -f 1 /proc/<pid>/stat" may not
equal <pid>.
This patch fixes the problem by converting to a single_open seq_file show
method. Getting the pid namespace from the filesystem superblock instead of
current, and simply using the the struct pid from the inode instead of
attempting to get that same pid from the task.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently many /proc/pid files use a crufty precursor to the current seq_file
api, and they don't have direct access to the pid_namespace or the pid of for
which they are displaying data.
So implement proc_single_file_operations to make the seq_file routines easy to
use, and to give access to the full state of the pid of we are displaying data
for.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch fixes a sles9 system hang in start_this_handle from a customer
with some heavy workload where all tasks are waiting on kjournald to commit
the transaction, but kjournald waits on t_updates to go down to zero (it
never does).
This was reported as a lowmem shortage deadlock but when checking the debug
data I noticed the VM wasn't under pressure at all (well it was really
under vm pressure, because lots of tasks hanged in the VM prune_dcache
methods trying to flush dirty inodes, but no task was hanging in GFP_NOFS
mode, the holder of the journal handle should have if this was a vm issue
in the first place).
No task was apparently holding the leftover handle in the committing
transaction, so I deduced t_updates was stuck to 1 because a journal_stop
was never run by some path (this turned out to be correct). With a debug
patch adding proper reverse links and stack trace logging in ext3 deployed
in production, I found journal_stop is never run because
mark_inode_dirty_sync is called inside release_task called by do_exit.
(that was quite fun because I would have never thought about this
subtleness, I thought a regular path in ext3 had a bug and it forgot to
call journal_stop)
do_exit->release_task->mark_inode_dirty_sync->schedule() (will never
come back to run journal_stop)
The reason is that shrink_dcache_parent is racy by design (feature not
a bug) and it can do blocking I/O in some case, but the point is that
calling shrink_dcache_parent at the last stage of do_exit isn't safe
for self-reaping tasks.
I guess the memory pressure of the unbalanced highmem system allowed
to trigger this more easily.
Now mainline doesn't have this line in iput (like sles9 has):
if (inode->i_state & I_DIRTY_DELAYED)
mark_inode_dirty_sync(inode);
so it will probably not crash with ext3, but for example ext2 implements an
I/O-blocking ext2_put_inode that will lead to similar screwups with
ext2_free_blocks never coming back and it's definitely wrong to call
blocking-IO paths inside do_exit. So this should fix a subtle bug in
mainline too (not verified in practice though). The equivalent fix for
ext3 is also not verified yet to fix the problem in sles9 but I don't have
doubt it will (it usually takes days to crash, so it'll take weeks to be
sure).
An alternate fix would be to offload that work to a kernel thread, but I
don't think a reschedule for this is worth it, the vm should be able to
collect those entries for the synchronous release_task.
Signed-off-by: Andrea Arcangeli <andrea@suse.de>
Cc: Jan Kara <jack@ucw.cz>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make /proc/ page monitoring configurable
This puts the following files under an embedded config option:
/proc/pid/clear_refs
/proc/pid/smaps
/proc/pid/pagemap
/proc/kpagecount
/proc/kpageflags
[akpm@linux-foundation.org: Kconfig fix]
Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This interface provides a mapping for each page in an address space to its
physical page frame number, allowing precise determination of what pages are
mapped and what pages are shared between processes.
New in this version:
- headers gone again (as recommended by Dave Hansen and Alan Cox)
- 64-bit entries (as per discussion with Andi Kleen)
- swap pte information exported (from Dave Hansen)
- page walker callback for holes (from Dave Hansen)
- direct put_user I/O (as suggested by Rusty Russell)
This patch folds in cleanups and swap PTE support from Dave Hansen
<haveblue@us.ibm.com>.
Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This puts all the clear_refs code where it belongs and probably lets things
compile on MMU-less systems as well.
Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'task_killable' of git://git.kernel.org/pub/scm/linux/kernel/git/willy/misc: (22 commits)
Remove commented-out code copied from NFS
NFS: Switch from intr mount option to TASK_KILLABLE
Add wait_for_completion_killable
Add wait_event_killable
Add schedule_timeout_killable
Use mutex_lock_killable in vfs_readdir
Add mutex_lock_killable
Use lock_page_killable
Add lock_page_killable
Add fatal_signal_pending
Add TASK_WAKEKILL
exit: Use task_is_*
signal: Use task_is_*
sched: Use task_contributes_to_load, TASK_ALL and TASK_NORMAL
ptrace: Use task_is_*
power: Use task_is_*
wait: Use TASK_NORMAL
proc/base.c: Use task_is_*
proc/array.c: Use TASK_REPORT
perfmon: Use task_is_*
...
Fixed up conflicts in NFS/sunrpc manually..
LatencyTOP kernel infrastructure; it measures latencies in the
scheduler and tracks it system wide and per process.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Contents of /proc/*/maps is sensitive and may become sensitive after
open() (e.g. if target originally shares our ->mm and later does exec
on suid-root binary).
Check at read() (actually, ->start() of iterator) time that mm_struct
we'd grabbed and locked is
- still the ->mm of target
- equal to reader's ->mm or the target is ptracable by reader.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Oleg noticed that the call of task_pid_nr_ns() in proc_pid_readdir
is racy with respect to tasks exiting.
After a bit of examination it also appears that the call itself
is completely unnecessary.
So to fix the problem this patch modifies next_tgid() to return
both a tgid and the task struct in question.
A structure is introduced to return these values because it is
slightly cleaner and easier to optimize, and the resulting code
is a little shorter.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently we special case when we have only the initial pid namespace.
Unfortunately in doing so the copied case for the other namespaces was
broken so we don't properly flush the thread directories :(
So this patch removes the unnecessary special case (removing a usage of
proc_mnt) and corrects the flushing of the thread directories.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Kirill Korotaev <dev@sw.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix mnt_flush_task() misplaced kernel-doc.
Fix typos in some of the doc text.
Warning(linux-2.6.23-git17//fs/proc/base.c:2280): No description found for parameter 'mnt'
Warning(linux-2.6.23-git17//fs/proc/base.c:2280): No description found for parameter 'pid'
Warning(linux-2.6.23-git17//fs/proc/base.c:2280): No description found for parameter 'tgid'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When removing the explicit task_struct->pid usage I found that
proc_readfd_common() and proc_pident_readdir() get this field, but do not
use it at all. So this cleanup is a cheap help with the task_struct->pid
isolation.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, there exists no method for a process to query the resource
limits of another process. They can be inferred via some mechanisms but
they cannot be explicitly determined. Given that this information can be
usefull to know during the debugging of an application, I've written this
patch which exports all of a processes limits via /proc/<pid>/limits.
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With pid namespaces this field is now dangerous to use explicitly, so hide
it behind the helpers.
Also the pid and pgrp fields o task_struct and signal_struct are to be
deprecated. Unfortunately this patch cannot be sent right now as this
leads to tons of warnings, so start isolating them, and deprecate later.
Actually the p->tgid == pid has to be changed to has_group_leader_pid(),
but Oleg pointed out that in case of posix cpu timers this is the same, and
thread_group_leader() is more preferable.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is the largest patch in the set. Make all (I hope) the places where
the pid is shown to or get from user operate on the virtual pids.
The idea is:
- all in-kernel data structures must store either struct pid itself
or the pid's global nr, obtained with pid_nr() call;
- when seeking the task from kernel code with the stored id one
should use find_task_by_pid() call that works with global pids;
- when showing pid's numerical value to the user the virtual one
should be used, but however when one shows task's pid outside this
task's namespace the global one is to be used;
- when getting the pid from userspace one need to consider this as
the virtual one and use appropriate task/pid-searching functions.
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: nuther build fix]
[akpm@linux-foundation.org: yet nuther build fix]
[akpm@linux-foundation.org: remove unneeded casts]
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The namespace's proc_mnt must be kern_mount-ed to make this pointer always
valid, independently of whether the user space mounted the proc or not. This
solves raced in proc_flush_task, etc. with the proc_mnt switching from NULL
to not-NULL.
The initialization is done after the init's pid is created and hashed to make
proc_get_sb() finr it and get for root inode.
Sice the namespace holds the vfsmnt, vfsmnt holds the superblock and the
superblock holds the namespace we must explicitly break this circle to destroy
all the stuff. This is done after the init of the namespace dies. Running a
few steps forward - when init exits it will kill all its children, so no
proc_mnt will be needed after its death.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This means that proc_flush_task_mnt() is to be called for many proc mounts and
with different ids, depending on the namespace this pid is to be flushed from.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When searching the task by numerical id on may need to find it using global
pid (as it is done now in kernel) or by its virtual id, e.g. when sending a
signal to a task from one namespace the sender will specify the task's virtual
id and we should find the task by this value.
[akpm@linux-foundation.org: fix gfs2 linkage]
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The first part is trivial - we just make the proc_flush_task() to operate on
arbitrary vfsmount with arbitrary ids and pass the pid and global proc_mnt to
it.
The other change is more tricky: I moved the proc_flush_task() call in
release_task() higher to address the following problem.
When flushing task from many proc trees we need to know the set of ids (not
just one pid) to find the dentries' names to flush. Thus we need to pass the
task's pid to proc_flush_task() as struct pid is the only object that can
provide all the pid numbers. But after __exit_signal() task has detached all
his pids and this information is lost.
This creates a tiny gap for proc_pid_lookup() to bring some dentries back to
tree and keep them in hash (since pids are still alive before __exit_signal())
till the next shrink, but since proc_flush_task() does not provide a 100%
guarantee that the dentries will be flushed, this is OK to do so.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When someone wants to deal with some other taks's namespaces it has to lock
the task and then to get the desired namespace if the one exists. This is
slow on read-only paths and may be impossible in some cases.
E.g. Oleg recently noticed a race between unshare() and the (sent for
review in cgroups) pid namespaces - when the task notifies the parent it
has to know the parent's namespace, but taking the task_lock() is
impossible there - the code is under write locked tasklist lock.
On the other hand switching the namespace on task (daemonize) and releasing
the namespace (after the last task exit) is rather rare operation and we
can sacrifice its speed to solve the issues above.
The access to other task namespaces is proposed to be performed
like this:
rcu_read_lock();
nsproxy = task_nsproxy(tsk);
if (nsproxy != NULL) {
/ *
* work with the namespaces here
* e.g. get the reference on one of them
* /
} / *
* NULL task_nsproxy() means that this task is
* almost dead (zombie)
* /
rcu_read_unlock();
This patch has passed the review by Eric and Oleg :) and,
of course, tested.
[clg@fr.ibm.com: fix unshare()]
[ebiederm@xmission.com: Update get_net_ns_by_pid]
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove the filesystem support logic from the cpusets system and makes cpusets
a cgroup subsystem
The "cpuset" filesystem becomes a dummy filesystem; attempts to mount it get
passed through to the cgroup filesystem with the appropriate options to
emulate the old cpuset filesystem behaviour.
Signed-off-by: Paul Menage <menage@google.com>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
