The perf_evlist__prepare_workload() method works by forking and then
waiting on a fd that must be written to to allow the workload to be
exec()ed.
But if the tool calling it fails to, say, set up the events with which
it wants to sample the workload for, it will not call
perf_evlist__start_workload(), but even in this case the workload ended
up running:
[acme@zoo linux]$ trace /bin/echo workload ends up running, it should not...
Couldn't mmap the events: Operation not permitted
workload ends up running, it should not...
[acme@zoo linux]$
So check if at least one byte was written before letting exec() be
called.
Now the expected behaviour:
[acme@zoo linux]$ trace /bin/echo workload ends up running, it should not...
Couldn't mmap the events: Operation not permitted
[acme@zoo linux]$
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@kernel.org>
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-oh1ixo8m74rf295a05gfjw8b@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Pull perf/core improvements and fixes from Arnaldo Carvalho de Melo:
Infrastructure changes:
o More prep work to support Intel PT: (Adrian Hunter)
- Polishing 'script' BTS output
- 'inject' can specify --kallsym
- VDSO is per machine, not a global var
- Expose data addr lookup functions previously private to 'script'
- Large mmap fixes in events processing
o Fix build on gcc 4.4.7 (Arnaldo Carvalho de Melo)
o Event ordering fixes (Jiri Olsa)
o Include standard stringify macros in power pc code (Sukadev Bhattiprolu)
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull perf fixes from Thomas Gleixner:
"A bunch of fixes for perf and kprobes:
- revert a commit that caused a perf group regression
- silence dmesg spam
- fix kprobe probing errors on ia64 and ppc64
- filter kprobe faults from userspace
- lockdep fix for perf exit path
- prevent perf #GP in KVM guest
- correct perf event and filters"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
kprobes: Fix "Failed to find blacklist" probing errors on ia64 and ppc64
kprobes/x86: Don't try to resolve kprobe faults from userspace
perf/x86/intel: Avoid spamming kernel log for BTS buffer failure
perf/x86/intel: Protect LBR and extra_regs against KVM lying
perf: Fix lockdep warning on process exit
perf/x86/intel/uncore: Fix SNB-EP/IVT Cbox filter mappings
perf/x86/intel: Use proper dTLB-load-misses event on IvyBridge
perf: Revert ("perf: Always destroy groups on exit")
Pull x86 fixes from Peter Anvin:
"A couple of crash fixes, plus a fix that on 32 bits would cause a
missing -ENOSYS for nonexistent system calls"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, cpu: Fix cache topology for early P4-SMT
x86_32, entry: Store badsys error code in %eax
x86, MCE: Robustify mcheck_init_device
Pull vfs fixes from Christoph Hellwig:
"A vfsmount leak fix, and a compile warning fix"
* 'vfs-for-3.16' of git://git.infradead.org/users/hch/vfs:
fs: umount on symlink leaks mnt count
direct-io: fix uninitialized warning in do_direct_IO()
Pull firewire regression fix from Stefan Richter:
"IEEE 1394 (FireWire) subsystem fix: MSI don't work on VIA PCIe
controllers with some isochronous workloads (regression since
v3.16-rc1)"
* tag 'firewire-fix-vt6315' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
firewire: ohci: disable MSI for VIA VT6315 again
Michel Dänzer and a couple of other people reported inexplicable random
oopses in the scheduler, and the cause turns out to be gcc mis-compiling
the load_balance() function when debugging is enabled. The gcc bug
apparently goes back to gcc-4.5, but slight optimization changes means
that it now showed up as a problem in 4.9.0 and 4.9.1.
The instruction scheduling problem causes gcc to schedule a spill
operation to before the stack frame has been created, which in turn can
corrupt the spilled value if an interrupt comes in. There may be other
effects of this bug too, but that's the code generation problem seen in
Michel's case.
This is fixed in current gcc HEAD, but the workaround as suggested by
Markus Trippelsdorf is pretty simple: use -fno-var-tracking-assignments
when compiling the kernel, which disables the gcc code that causes the
problem. This can result in slightly worse debug information for
variable accesses, but that is infinitely preferable to actual code
generation problems.
Doing this unconditionally (not just for CONFIG_DEBUG_INFO) also allows
non-debug builds to verify that the debug build would be identical: we
can do
export GCC_COMPARE_DEBUG=1
to make gcc internally verify that the result of the build is
independent of the "-g" flag (it will make the compiler build everything
twice, toggling the debug flag, and compare the results).
Without the "-fno-var-tracking-assignments" option, the build would fail
(even with 4.8.3 that didn't show the actual stack frame bug) with a gcc
compare failure.
See also gcc bugzilla:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61801
Reported-by: Michel Dänzer <michel@daenzer.net>
Suggested-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: Jakub Jelinek <jakub@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Shortly before 3.16-rc1, Dave Jones reported:
WARNING: CPU: 3 PID: 19721 at fs/xfs/xfs_aops.c:971
xfs_vm_writepage+0x5ce/0x630 [xfs]()
CPU: 3 PID: 19721 Comm: trinity-c61 Not tainted 3.15.0+ #3
Call Trace:
xfs_vm_writepage+0x5ce/0x630 [xfs]
shrink_page_list+0x8f9/0xb90
shrink_inactive_list+0x253/0x510
shrink_lruvec+0x563/0x6c0
shrink_zone+0x3b/0x100
shrink_zones+0x1f1/0x3c0
try_to_free_pages+0x164/0x380
__alloc_pages_nodemask+0x822/0xc90
alloc_pages_vma+0xaf/0x1c0
handle_mm_fault+0xa31/0xc50
etc.
970 if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) ==
971 PF_MEMALLOC))
I did not respond at the time, because a glance at the PageDirty block
in shrink_page_list() quickly shows that this is impossible: we don't do
writeback on file pages (other than tmpfs) from direct reclaim nowadays.
Dave was hallucinating, but it would have been disrespectful to say so.
However, my own /var/log/messages now shows similar complaints
WARNING: CPU: 1 PID: 28814 at fs/ext4/inode.c:1881 ext4_writepage+0xa7/0x38b()
WARNING: CPU: 0 PID: 27347 at fs/ext4/inode.c:1764 ext4_writepage+0xa7/0x38b()
from stressing some mmotm trees during July.
Could a dirty xfs or ext4 file page somehow get marked PageSwapBacked,
so fail shrink_page_list()'s page_is_file_cache() test, and so proceed
to mapping->a_ops->writepage()?
Yes, 3.16-rc1's commit 68711a7463 ("mm, migration: add destination
page freeing callback") has provided such a way to compaction: if
migrating a SwapBacked page fails, its newpage may be put back on the
list for later use with PageSwapBacked still set, and nothing will clear
it.
Whether that can do anything worse than issue WARN_ON_ONCEs, and get
some statistics wrong, is unclear: easier to fix than to think through
the consequences.
Fixing it here, before the put_new_page(), addresses the bug directly,
but is probably the worst place to fix it. Page migration is doing too
many parts of the job on too many levels: fixing it in
move_to_new_page() to complement its SetPageSwapBacked would be
preferable, except why is it (and newpage->mapping and newpage->index)
done there, rather than down in migrate_page_move_mapping(), once we are
sure of success? Not a cleanup to get into right now, especially not
with memcg cleanups coming in 3.17.
Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull drm fixes from Dave Airlie:
"This is radeon and intel fixes, and is a small bit larger than I'm
guessing you'd like it to be.
- i915: fixes 32-bit highmem i915 blank screen, semaphore hang and
runtime pm fix
- radeon: gpuvm stability fix for hangs since 3.15, and hang/reboot
regression on TN/RL devices,
The only slightly controversial one is the change to use GB for the
vm_size, which I'm letting through as its a new interface we defined
in this merge window, and I'd prefer to have the released kernel have
the final interface rather than changing it later"
* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
drm/radeon: fix cut and paste issue for hawaii.
drm/radeon: fix irq ring buffer overflow handling
drm/i915: Simplify i915_gem_release_all_mmaps()
drm/radeon: fix error handling in radeon_vm_bo_set_addr
drm/i915: fix freeze with blank screen booting highmem
drm/i915: Reorder the semaphore deadlock check, again
drm/radeon/TN: only enable bapm on MSI systems
drm/radeon: fix VM IB handling
drm/radeon: fix handling of radeon_vm_bo_rmv v3
drm/radeon: let's use GB for vm_size (v2)
Pull sound fixes from Takashi Iwai:
"Here contains only the fixes for the new FireWire bebob driver. All
fairly trivial and local fixes, so safe to apply"
* tag 'sound-3.16-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
ALSA: bebob: Correction for return value of special_clk_ctl_put() in error
ALSA: bebob: Correction for return value of .put callback
ALSA: bebob: Use different labels for digital input/output
ALSA: bebob: Fix a missing to unlock mutex in error handling case
Pull hwmon fix from Guenter Roeck:
"Fixes to temperature limit and vrm write operations in smsc47m192
driver"
* tag 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
hwmon: (smsc47m192) Fix temperature limit and vrm write operations
Do not split the PARPORT-related symbols with the new kconfig
symbol ARCH_MIGHT_HAVE_PC_PARPORT. The split was causing incorrect
display of these symbols -- they were not being displayed together
as they should be.
Fixes: d90c3eb315 "Kconfig cleanup (PARPORT_PC dependencies)"
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Mark Salter <msalter@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: stable@vger.kernel.org # for 3.13, 3.14, 3.15
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull blackfin fixes from Steven Miao:
"smc nor flash PM fix, pinctrl group fix, update defconfig, and build
fixes"
* tag 'blackfin-3.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/realmz6/blackfin-linux:
blackfin: vmlinux.lds.S: reserve 32 bytes space at the end of data section for XIP kernel
defconfig: BF609: update spi config name
irq: blackfin sec: drop duplicated sec priority set
blackfin: bind different groups of one pinmux function to different state name
blackfin: fix some bf5xx boards build for missing <linux/gpio.h>
pm: bf609: cleanup smc nor flash
Arnaldo Carvalho de Melo
Mark Salter
Ingo Molnar
Jiri Olsa
Linus Torvalds
Hugh Dickins
Randy Dunlap
Steven Miao
Sonic Zhang