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  1. 18 Jun, 2012 1 commit
    • Salman Qazi's avatar
      perf: Use css_tryget() to avoid propping up css refcount · 9c5da09d
      Salman Qazi authored 
      An rmdir pushes css's ref count to zero.  However, if the associated
directory is open at the time, the dentry ref count is non-zero.  If
the fd for this directory is then passed into perf_event_open, it
does a css_get().  This bounces the ref count back up from zero.  This
is a problem by itself.  But what makes it turn into a crash is the
fact that we end up doing an extra dput, since we perform a dput
when css_put sees the ref count go down to zero.

css_tryget() does not fall into that trap. So, we use that instead.

Reproduction test-case for the bug:

 #include <unistd.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <linux/unistd.h>
 #include <linux/perf_event.h>
 #include <string.h>
 #include <errno.h>
 #include <stdio.h>

 #define PERF_FLAG_PID_CGROUP    (1U << 2)

 int perf_event_open(struct perf_event_attr *hw_event_uptr,
                     pid_t pid, int cpu, int group_fd, unsigned long flags) {
         return syscall(__NR_perf_event_open,hw_event_uptr, pid, cpu,
                 group_fd, flags);
 }

 /*
  * Directly poke at the perf_event bug, since it's proving hard to repro
  * depending on where in the kernel tree.  what moved?
  */
 int main(int argc, char **argv)
 {
        int fd;
        struct perf_event_attr attr;
        memset(&attr, 0, sizeof(attr));
        attr.exclude_kernel = 1;
        attr.size = sizeof(attr);
        mkdir("/dev/cgroup/perf_event/blah", 0777);
        fd = open("/dev/cgroup/perf_event/blah", O_RDONLY);
        perror("open");
        rmdir("/dev/cgroup/perf_event/blah");
        sleep(2);
        perf_event_open(&attr, fd, 0, -1,  PERF_FLAG_PID_CGROUP);
        perror("perf_event_open");
        close(fd);
        return 0;
 }
Signed-off-by: default avatarSalman Qazi <sqazi@google.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/20120614223108.1025.2503.stgit@dungbeetle.mtv.corp.google.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      9c5da09d
  3. 15 Jun, 2012 1 commit
  5. 14 Jun, 2012 1 commit
    • Don Zickus's avatar
      watchdog: Quiet down the boot messages · a7027046
      Don Zickus authored 
      A bunch of bugzillas have complained how noisy the nmi_watchdog
is during boot-up especially with its expected failure cases
(like virt and bios resource contention).

This is my attempt to quiet them down and keep it less confusing
for the end user.  What I did is print the message for cpu0 and
save it for future comparisons.  If future cpus have an
identical message as cpu0, then don't print the redundant info.
However, if a future cpu has a different message, happily print
that loudly.

Before the change, you would see something like:

    ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
    CPU0: Intel(R) Core(TM)2 Quad CPU    Q9550  @ 2.83GHz stepping 0a
    Performance Events: PEBS fmt0+, Core2 events, Intel PMU driver.
    ... version:                2
    ... bit width:              40
    ... generic registers:      2
    ... value mask:             000000ffffffffff
    ... max period:             000000007fffffff
    ... fixed-purpose events:   3
    ... event mask:             0000000700000003
    NMI watchdog enabled, takes one hw-pmu counter.
    Booting Node   0, Processors  #1
    NMI watchdog enabled, takes one hw-pmu counter.
     #2
    NMI watchdog enabled, takes one hw-pmu counter.
     #3 Ok.
    NMI watchdog enabled, takes one hw-pmu counter.
    Brought up 4 CPUs
    Total of 4 processors activated (22607.24 BogoMIPS).

After the change, it is simplified to:

    ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
    CPU0: Intel(R) Core(TM)2 Quad CPU    Q9550  @ 2.83GHz stepping 0a
    Performance Events: PEBS fmt0+, Core2 events, Intel PMU driver.
    ... version:                2
    ... bit width:              40
    ... generic registers:      2
    ... value mask:             000000ffffffffff
    ... max period:             000000007fffffff
    ... fixed-purpose events:   3
    ... event mask:             0000000700000003
    NMI watchdog: enabled on all CPUs, permanently consumes one hw-PMU counter.
    Booting Node   0, Processors  #1 #2 #3 Ok.
    Brought up 4 CPUs

V2: little changes based on Joe Perches' feedback
V3: printk cleanup based on Ingo's feedback; checkpatch fix
V4: keep printk as one long line
V5: Ingo fix ups
Reported-and-tested-by: default avatarNathan Zimmer <nzimmer@sgi.com>
Signed-off-by: default avatarDon Zickus <dzickus@redhat.com>
Cc: nzimmer@sgi.com
Cc: joe@perches.com
Link: http://lkml.kernel.org/r/1339594548-17227-1-git-send-email-dzickus@redhat.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      a7027046
  7. 13 Jun, 2012 1 commit
  9. 12 Jun, 2012 1 commit
    • Arnaldo Carvalho de Melo's avatar
      perf tools: Fix synthesizing tracepoint names from the perf.data headers · cb9dd49e
      Arnaldo Carvalho de Melo authored 
      We need to use the per event info snapshoted at record time to
synthesize the events name, so do it just after reading the perf.data
headers, when we already processed the /sys events data, otherwise we'll
end up using the local /sys that only by sheer luck will have the same
tracepoint ID -> real event association.

Example:

  # uname -a
  Linux felicio.ghostprotocols.net 3.4.0-rc5+ #1 SMP Sat May 19 15:27:11 BRT 2012 x86_64 x86_64 x86_64 GNU/Linux
  # perf record -e sched:sched_switch usleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.015 MB perf.data (~648 samples) ]
  # cat /t/events/sched/sched_switch/id
  279
  # perf evlist -v
  sched:sched_switch: sample_freq=1, type: 2, config: 279, size: 80, sample_type: 1159, read_format: 7, disabled: 1, inherit: 1, mmap: 1, comm: 1, enable_on_exec: 1, sample_id_all: 1, exclude_guest: 1
  #

So on the above machine the sched:sched_switch has tracepoint id 279, but on
the machine were we'll analyse it it has a different id:

  $ cat /t/events/sched/sched_switch/id
  56
  $ perf evlist -i /tmp/perf.data
  kmem:mm_balancedirty_writeout
  $ cat /t/events/kmem/mm_balancedirty_writeout/id
  279

With this fix:

  $ perf evlist -i /tmp/perf.data
  sched:sched_switch
Reported-by: default avatarDmitry Antipov <dmitry.antipov@linaro.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-auwks8fpuhmrdpiefs55o5oz@git.kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      cb9dd49e
  11. 11 Jun, 2012 2 commits
    • Stephane Eranian's avatar
      perf stat: Fix default output file · fc3e4d07
      Stephane Eranian authored 
      The following commit:

commit 56f3bae7
Author: Jim Cromie <jim.cromie@gmail.com>
Date:   Wed Sep 7 17:14:00 2011 -0600

    perf stat: Add --log-fd <N> option to redirect stderr elsewhere

introduced a bug in the way perf stat outputs the results by default,
i.e., without the --log-fd or --output option. It would default to
writing to file descriptor 0, i.e., stdin. Writing to stdin is allowed
and is equivalent to writing to stdout. However, there is a major
difference for any script that was already capturing the output of perf
stat via redirection:

    perf stat >/tmp/log .... or perf stat 2>/tmp/log ....

They would not capture anything anymore. They would have to do:
    perf stat 0>/tmp/log ...

This breaks compatibility with existing scripts and does not look very
natural.

This patch fixes the problem by looking at output_fd only when it was
modified by user (> 0). It also checks that the value if positive.
Passing --log-fd 0 is ignored.

I would also argue that defaulting to stderr for the results is not the
right thing to do, though this patch does not address this specific
issue.
Signed-off-by: default avatarStephane Eranian <eranian@google.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jim Cromie <jim.cromie@gmail.com>
Link: http://lkml.kernel.org/r/20120515111111.GA9870@quadSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      fc3e4d07
    • David Ahern's avatar
      perf tools: Fix endianity swapping for adds_features bitmask · 80c0120a
      David Ahern authored 
      Based on Jiri's latest attempt:
https://lkml.org/lkml/2012/5/16/61

Basically, adds_features should be byte swapped assuming unsigned
longs are either 8-bytes (u64) or 4-bytes (u32).

    Fixes 32-bit ppc dumping 64-bit x86 feature data:
     ========
     captured on: Sun May 20 19:23:23 2012
     hostname : nxos-vdc-dev3
     os release : 3.4.0-rc7+
     perf version : 3.4.rc4.137.g978da3
     arch : x86_64
     nrcpus online : 16
     nrcpus avail : 16
     cpudesc : Intel(R) Xeon(R) CPU E5540 @ 2.53GHz
     cpuid : GenuineIntel,6,26,5
     total memory : 24680324 kB
    ...

Verified 64-bit x86 can still dump feature data for 32-bit ppc.
Signed-off-by: default avatarDavid Ahern <dsahern@gmail.com>
Reviewed-by: default avatarJiri Olsa <jolsa@redhat.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/4FBBB539.5010805@gmail.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      80c0120a
  13. 08 Jun, 2012 1 commit
  15. 07 Jun, 2012 1 commit
    • Steven Rostedt's avatar
      tracing: Have tracing_off() actually turn tracing off · f2bf1f6f
      Steven Rostedt authored 
      A recent update to have tracing_on/off() only affect the ftrace ring
buffers instead of all ring buffers had a cut and paste error.
The tracing_off() did the exact same thing as tracing_on() and
would not actually turn off tracing. Unfortunately, tracing_off()
is more important to be working than tracing_on() as this is a key
development tool, as it lets the developer turn off tracing as soon
as a problem is discovered. It is also used by panic and oops code.

This bug also breaks the 'echo func:traceoff > set_ftrace_filter'

Cc: <stable@vger.kernel.org> # 3.4
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      f2bf1f6f
  17. 06 Jun, 2012 10 commits
  19. 05 Jun, 2012 2 commits
  21. 04 Jun, 2012 12 commits
  23. 03 Jun, 2012 3 commits
    • Linus Torvalds's avatar
      vfs: move inode stat information closer together · 2f9d3df8
      Linus Torvalds authored 
      The comment above it says "Stat data, not accessed from path walking",
but in fact some of inode fields we use for the common stat data was way
down at the end of the inode, causing unnecessary cache misses for the
common stat operations.

The inode structure is pretty big, and this can change padding depending
on field width, but at least on the common 64-bit configurations this
doesn't change the size.  Some of our inode layout has historically been
to tro to avoid unnecessary padding fields, but cache locality is at
least as important for layout, if not more.

Noticed by looking at kernel profiles, and noticing that the "i_blkbits"
access stood out like a sore thumb.
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2f9d3df8
    • Linus Torvalds's avatar
      Linux 3.5-rc1 · f8f5701b
      Linus Torvalds authored
      f8f5701b
    • Linus Torvalds's avatar
      Merge tag 'dm-3.5-changes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm · 912afc36
      Linus Torvalds authored 
      Pull device-mapper updates from Alasdair G Kergon:
 "Improve multipath's retrying mechanism in some defined circumstances
  and provide a simple reserve/release mechanism for userspace tools to
  access thin provisioning metadata while the pool is in use."

* tag 'dm-3.5-changes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm:
  dm thin: provide userspace access to pool metadata
  dm thin: use slab mempools
  dm mpath: allow ioctls to trigger pg init
  dm mpath: delay retry of bypassed pg
  dm mpath: reduce size of struct multipath
      912afc36
  25. 02 Jun, 2012 4 commits
    • Joe Thornber's avatar
      dm thin: provide userspace access to pool metadata · cc8394d8
      Joe Thornber authored 
      This patch implements two new messages that can be sent to the thin
pool target allowing it to take a snapshot of the _metadata_.  This,
read-only snapshot can be accessed by userland, concurrently with the
live target.

Only one metadata snapshot can be held at a time.  The pool's status
line will give the block location for the current msnap.

Since version 0.1.5 of the userland thin provisioning tools, the
thin_dump program displays the msnap as follows:

    thin_dump -m <msnap root> <metadata dev>

Available here: https://github.com/jthornber/thin-provisioning-tools

Now that userland can access the metadata we can do various things
that have traditionally been kernel side tasks:

     i) Incremental backups.

     By using metadata snapshots we can work out what blocks have
     changed over time.  Combined with data snapshots we can ensure
     the data doesn't change while we back it up.

     A short proof of concept script can be found here:

     https://github.com/jthornber/thinp-test-suite/blob/master/incremental_backup_example.rb

     ii) Migration of thin devices from one pool to another.

     iii) Merging snapshots back into an external origin.

     iv) Asyncronous replication.
Signed-off-by: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
      cc8394d8
    • Mike Snitzer's avatar
      dm thin: use slab mempools · a24c2569
      Mike Snitzer authored 
      Use dedicated caches prefixed with a "dm_" name rather than relying on
kmalloc mempools backed by generic slab caches so the memory usage of
thin provisioning (and any leaks) can be accounted for independently.
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
      a24c2569
    • Mikulas Patocka's avatar
      dm mpath: allow ioctls to trigger pg init · 35991652
      Mikulas Patocka authored 
      After the failure of a group of paths, any alternative paths that
need initialising do not become available until further I/O is sent to
the device.  Until this has happened, ioctls return -EAGAIN.

With this patch, new paths are made available in response to an ioctl
too.  The processing of the ioctl gets delayed until this has happened.

Instead of returning an error, we submit a work item to kmultipathd
(that will potentially activate the new path) and retry in ten
milliseconds.

Note that the patch doesn't retry an ioctl if the ioctl itself fails due
to a path failure.  Such retries should be handled intelligently by the
code that generated the ioctl in the first place, noting that some SCSI
commands should not be retried because they are not idempotent (XOR write
commands).  For commands that could be retried, there is a danger that
if the device rejected the SCSI command, the path could be errorneously
marked as failed, and the request would be retried on another path which
might fail too.  It can be determined if the failure happens on the
device or on the SCSI controller, but there is no guarantee that all
SCSI drivers set these flags correctly.
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
      35991652
    • Mike Christie's avatar
      dm mpath: delay retry of bypassed pg · f220fd4e
      Mike Christie authored 
      If I/O needs retrying and only bypassed priority groups are available,
set the pg_init_delay_retry flag to wait before retrying.

If, for example, the reason for the bypass is that the controller is
getting reset or there is a firmware upgrade happening, retrying right
away would cause a flood of log messages and retries for what could be a
few seconds or even several minutes.
Signed-off-by: default avatarMike Christie <michaelc@cs.wisc.edu>
Acked-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
      f220fd4e
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