linux-stable.git/Documentation/filesystems, branch linux-2.6.33.y

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

2010-05-26T21:32:04+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

doc: add the documentation for mpol=local

2010-04-01T23:01:32+00:00

commit 5574169613b40b85d6f4c67208fa4846b897a0a1 upstream.

commit 3f226aa1c (mempolicy: support mpol=local tmpfs mount option) added
new mpol=local mount option.  but it didn't add a documentation.

This patch does it.

Signed-off-by: KOSAKI Motohiro 
Cc: Ravikiran Thirumalai 
Cc: Christoph Lameter 
Cc: Mel Gorman 
Acked-by: Lee Schermerhorn 
Cc: Hugh Dickins 
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"

2010-01-11T17:34:06+00:00

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

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ryusuke/nilfs2

2010-01-04T20:28:26+00:00

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ryusuke/nilfs2:
  nilfs2: update mailing list address
  nilfs2: Storage class should be before const qualifier
  nilfs2: trivial coding style fix

nilfs2: update mailing list address

2010-01-02T12:47:04+00:00

This replaces the list address for nilfs discussion to linux-nilfs at
vger.kernel.org from users at nilfs.org.

Signed-off-by: Ryusuke Konishi

ext4: Update documentation to correct the inode_readahead_blks option name

2009-12-24T22:51:42+00:00

Per commit 240799cd, the option name for readahead should be
inode_readahead_blks, not inode_readahead.

Signed-off-by: Fang Wenqi 
Signed-off-by: "Theodore Ts'o"

Driver core: driver_attribute parameters can often be const*

2009-12-23T19:23:43+00:00

Many struct driver_attribute descriptors are purely read-only
structures, and there's no need to change them. Therefore make
the promise not to, which will let those descriptors be put in
a ro section.

Signed-off-by: Phil Carmody 
Signed-off-by: Greg Kroah-Hartman

Driver core: device_attribute parameters can often be const*

2009-12-23T19:23:43+00:00

Most device_attributes are const, and are begging to be
put in a ro section. However, the create and remove
file interfaces were failing to propagate the const promise
which the only functions they call offer.

Signed-off-by: Phil Carmody 
Signed-off-by: Greg Kroah-Hartman

Merge branch 'for-2.6.33' of git://linux-nfs.org/~bfields/linux

2009-12-16T18:43:34+00:00

* 'for-2.6.33' of git://linux-nfs.org/~bfields/linux: (42 commits)
  nfsd: remove pointless paths in file headers
  nfsd: move most of nfsfh.h to fs/nfsd
  nfsd: remove unused field rq_reffh
  nfsd: enable V4ROOT exports
  nfsd: make V4ROOT exports read-only
  nfsd: restrict filehandles accepted in V4ROOT case
  nfsd: allow exports of symlinks
  nfsd: filter readdir results in V4ROOT case
  nfsd: filter lookup results in V4ROOT case
  nfsd4: don't continue "under" mounts in V4ROOT case
  nfsd: introduce export flag for v4 pseudoroot
  nfsd: let "insecure" flag vary by pseudoflavor
  nfsd: new interface to advertise export features
  nfsd: Move private headers to source directory
  vfs: nfsctl.c un-used nfsd #includes
  lockd: Remove un-used nfsd headers #includes
  s390: remove un-used nfsd #includes
  sparc: remove un-used nfsd #includes
  parsic: remove un-used nfsd #includes
  compat.c: Remove dependence on nfsd private headers
  ...

seq_file: use proc_create() in documentation

2009-12-16T15:20:07+00:00

Using create_proc_entry() + ->proc_fops assignment is racy because
->proc_fops will be NULL for some time, use proc_create() to avoid race.

Signed-off-by: Alexey Dobriyan 
Cc: Randy Dunlap 
Cc: Jonathan Corbet 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds