linux-toradex.git/kernel/fork.c, branch v2.6.20.21

initialise pi_lock if CONFIG_RT_MUTEXES=N

2007-03-23T19:49:23+00:00

Fixes a bogus lockdep warning which causes lockdep to disable itself.

Acked-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

[PATCH] fork_idle() should be cpuinit, not devinit

2007-02-02T00:17:06+00:00

Signed-off-by: Al Viro 
Signed-off-by: Linus Torvalds

Revert "[PATCH] namespaces: fix exit race by splitting exit"

2007-01-30T21:35:18+00:00

This reverts commit 7a238fcba0629b6f2edbcd37458bae56fcf36be5 in
preparation for a better and simpler fix proposed by Eric Biederman
(and fixed up by Serge Hallyn)

Acked-by: Serge E. Hallyn 
Signed-off-by: Linus Torvalds

[PATCH] namespaces: fix exit race by splitting exit

2007-01-30T16:26:44+00:00

Fix exit race by splitting the nsproxy putting into two pieces.  First
piece reduces the nsproxy refcount.  If we dropped the last reference, then
it puts the mnt_ns, and returns the nsproxy as a hint to the caller.  Else
it returns NULL.  The second piece of exiting task namespaces sets
tsk->nsproxy to NULL, and drops the references to other namespaces and
frees the nsproxy only if an nsproxy was passed in.

A little awkward and should probably be reworked, but hopefully it fixes
the NFS oops.

Signed-off-by: Serge E. Hallyn 
Cc: Herbert Poetzl 
Cc: Oleg Nesterov 
Cc: "Eric W. Biederman" 
Cc: Cedric Le Goater 
Cc: Daniel Hokka Zakrisson 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Optimize D-cache alias handling on fork

2006-12-13T17:27:08+00:00

Virtually index, physically tagged cache architectures can get away
without cache flushing when forking.  This patch adds a new cache
flushing function flush_cache_dup_mm(struct mm_struct *) which for the
moment I've implemented to do the same thing on all architectures
except on MIPS where it's a no-op.

Signed-off-by: Ralf Baechle 
Signed-off-by: Linus Torvalds

[PATCH] fdtable: Remove the free_files field

2006-12-10T17:57:22+00:00

An fdtable can either be embedded inside a files_struct or standalone (after
being expanded).  When an fdtable is being discarded after all RCU references
to it have expired, we must either free it directly, in the standalone case,
or free the files_struct it is contained within, in the embedded case.

Currently the free_files field controls this behavior, but we can get rid of
it entirely, as all the necessary information is already recorded.  We can
distinguish embedded and standalone fdtables using max_fds, and if it is
embedded we can divine the relevant files_struct using container_of().

Signed-off-by: Vadim Lobanov 
Cc: Christoph Hellwig 
Cc: Al Viro 
Cc: Dipankar Sarma 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] fdtable: Make fdarray and fdsets equal in size

2006-12-10T17:57:22+00:00

Currently, each fdtable supports three dynamically-sized arrays of data: the
fdarray and two fdsets.  The code allows the number of fds supported by the
fdarray (fdtable->max_fds) to differ from the number of fds supported by each
of the fdsets (fdtable->max_fdset).

In practice, it is wasteful for these two sizes to differ: whenever we hit a
limit on the smaller-capacity structure, we will reallocate the entire fdtable
and all the dynamic arrays within it, so any delta in the memory used by the
larger-capacity structure will never be touched at all.

Rather than hogging this excess, we shouldn't even allocate it in the first
place, and keep the capacities of the fdarray and the fdsets equal.  This
patch removes fdtable->max_fdset.  As an added bonus, most of the supporting
code becomes simpler.

Signed-off-by: Vadim Lobanov 
Cc: Christoph Hellwig 
Cc: Al Viro 
Cc: Dipankar Sarma 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] fdtable: Delete pointless code in dup_fd()

2006-12-10T17:57:21+00:00

The dup_fd() function creates a new files_struct and fdtable embedded inside
that files_struct, and then possibly expands the fdtable using expand_files().

The out_release error path is invoked when expand_files() returns an error
code.  However, when this attempt to expand fails, the fdtable is left in its
original embedded form, so it is pointless to try to free the associated
fdarray and fdsets.

Signed-off-by: Vadim Lobanov 
Cc: Dipankar Sarma 
Cc: Christoph Hellwig 
Cc: Al Viro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] io-accounting: core statistics

2006-12-10T17:55:41+00:00

The present per-task IO accounting isn't very useful.  It simply counts the
number of bytes passed into read() and write().  So if a process reads 1MB
from an already-cached file, it is accused of having performed 1MB of I/O,
which is wrong.

(David Wright had some comments on the applicability of the present logical IO accounting:

  For billing purposes it is useless but for workload analysis it is very
  useful

  read_bytes/read_calls  average read request size
  write_bytes/write_calls average write request size

  read_bytes/read_blocks ie logical/physical can indicate hit rate or thrashing
  write_bytes/write_blocks  ie logical/physical  guess since pdflush writes can
                                                be missed

  I often look for logical larger than physical to see filesystem cache
  problems.  And the bytes/cpusec can help find applications that are
  dominating the cache and causing slow interactive response from page cache
  contention.

  I want to find the IO intensive applications and make sure they are doing
  efficient IO.  Thus the acctcms(sysV) or csacms command would give the high
  IO commands).

This patchset adds new accounting which tries to be more accurate.  We account
for three things:

reads:

  attempt to count the number of bytes which this process really did cause
  to be fetched from the storage layer.  Done at the submit_bio() level, so it
  is accurate for block-backed filesystems.  I also attempt to wire up NFS and
  CIFS.

writes:

  attempt to count the number of bytes which this process caused to be sent
  to the storage layer.  This is done at page-dirtying time.

  The big inaccuracy here is truncate.  If a process writes 1MB to a file
  and then deletes the file, it will in fact perform no writeout.  But it will
  have been accounted as having caused 1MB of write.

  So...

cancelled_writes:

  account the number of bytes which this process caused to not happen, by
  truncating pagecache.

  We _could_ just subtract this from the process's `write' accounting.  But
  that means that some processes would be reported to have done negative
  amounts of write IO, which is silly.

  So we just report the raw number and punt this decision up to userspace.

Now, we _could_ account for writes at the physical I/O level.  But

- This would require that we track memory-dirtying tasks at the per-page
  level (would require a new pointer in struct page).

- It would mean that IO statistics for a process are usually only available
  long after that process has exitted.  Which means that we probably cannot
  communicate this info via taskstats.

This patch:

Wire up the kernel-private data structures and the accessor functions to
manipulate them.

Cc: Jay Lan 
Cc: Shailabh Nagar 
Cc: Balbir Singh 
Cc: Chris Sturtivant 
Cc: Tony Ernst 
Cc: Guillaume Thouvenin 
Cc: David Wright 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] rename struct namespace to struct mnt_namespace

2006-12-08T16:28:51+00:00

Rename 'struct namespace' to 'struct mnt_namespace' to avoid confusion with
other namespaces being developped for the containers : pid, uts, ipc, etc.
'namespace' variables and attributes are also renamed to 'mnt_ns'

Signed-off-by: Kirill Korotaev 
Signed-off-by: Cedric Le Goater 
Cc: Eric W. Biederman 
Cc: Herbert Poetzl 
Cc: Sukadev Bhattiprolu 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds