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  1. 25 11月, 2015 1 次提交
  3. 21 11月, 2015 2 次提交
    • V
      kernel/panic.c: turn off locks debug before releasing console lock · 7625b3a0
      由 Vitaly Kuznetsov 提交于 
      Commit 08d78658 ("panic: release stale console lock to always get the
logbuf printed out") introduced an unwanted bad unlock balance report when
panic() is called directly and not from OOPS (e.g.  from out_of_memory()).
The difference is that in case of OOPS we disable locks debug in
oops_enter() and on direct panic call nobody does that.

Fixes: 08d78658 ("panic: release stale console lock to always get the logbuf printed out")
Reported-by: Nkernel test robot <ying.huang@linux.intel.com>
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Baoquan He <bhe@redhat.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Xie XiuQi <xiexiuqi@huawei.com>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Petr Mladek <pmladek@suse.cz>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      7625b3a0
    • R
      kernel/signal.c: unexport sigsuspend() · 9d8a7652
      由 Richard Weinberger 提交于 
      sigsuspend() is nowhere used except in signal.c itself, so we can mark it
static do not pollute the global namespace.

But this patch is more than a boring cleanup patch, it fixes a real issue
on UserModeLinux.  UML has a special console driver to display ttys using
xterm, or other terminal emulators, on the host side.  Vegard reported
that sometimes UML is unable to spawn a xterm and he's facing the
following warning:

  WARNING: CPU: 0 PID: 908 at include/linux/thread_info.h:128 sigsuspend+0xab/0xc0()

It turned out that this warning makes absolutely no sense as the UML
xterm code calls sigsuspend() on the host side, at least it tries.  But
as the kernel itself offers a sigsuspend() symbol the linker choose this
one instead of the glibc wrapper.  Interestingly this code used to work
since ever but always blocked signals on the wrong side.  Some recent
kernel change made the WARN_ON() trigger and uncovered the bug.

It is a wonderful example of how much works by chance on computers. :-)

Fixes: 68f3f16d ("new helper: sigsuspend()")
Signed-off-by: NRichard Weinberger <richard@nod.at>
Reported-by: NVegard Nossum <vegard.nossum@oracle.com>
Tested-by: NVegard Nossum <vegard.nossum@oracle.com>
Acked-by: NOleg Nesterov <oleg@redhat.com>
Cc: <stable@vger.kernel.org>	[3.5+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      9d8a7652
  5. 12 11月, 2015 1 次提交
  7. 11 11月, 2015 1 次提交
    • S
      bpf_trace: Make dependent on PERF_EVENTS · a31d82d8
      由 Steven Rostedt 提交于 
      Arnd Bergmann reported:

  In my ARM randconfig tests, I'm getting a build error for
  newly added code in bpf_perf_event_read and bpf_perf_event_output
  whenever CONFIG_PERF_EVENTS is disabled:

  kernel/trace/bpf_trace.c: In function 'bpf_perf_event_read':
  kernel/trace/bpf_trace.c:203:11: error: 'struct perf_event' has no member named 'oncpu'
  if (event->oncpu != smp_processor_id() ||
           ^
  kernel/trace/bpf_trace.c:204:11: error: 'struct perf_event' has no member named 'pmu'
        event->pmu->count)

  This can happen when UPROBE_EVENT is enabled but KPROBE_EVENT
  is disabled. I'm not sure if that is a configuration we care
  about, otherwise we could prevent this case from occuring by
  adding Kconfig dependencies.

Looking at this further, it's really that UPROBE_EVENT enables PERF_EVENTS.
By just having BPF_EVENTS depend on PERF_EVENTS, then all is fine.

Link: http://lkml.kernel.org/r/4525348.Aq9YoXkChv@wuerfelReported-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      a31d82d8
  9. 10 11月, 2015 5 次提交
  11. 09 11月, 2015 3 次提交
  13. 08 11月, 2015 1 次提交
  15. 07 11月, 2015 9 次提交
    • V
      panic: release stale console lock to always get the logbuf printed out · 08d78658
      由 Vitaly Kuznetsov 提交于 
      In some cases we may end up killing the CPU holding the console lock
while still having valuable data in logbuf. E.g. I'm observing the
following:

- A crash is happening on one CPU and console_unlock() is being called on
  some other.

- console_unlock() tries to print out the buffer before releasing the lock
  and on slow console it takes time.

- in the meanwhile crashing CPU does lots of printk()-s with valuable data
  (which go to the logbuf) and sends IPIs to all other CPUs.

- console_unlock() finishes printing previous chunk and enables interrupts
  before trying to print out the rest, the CPU catches the IPI and never
  releases console lock.

This is not the only possible case: in VT/fb subsystems we have many other
console_lock()/console_unlock() users.  Non-masked interrupts (or
receiving NMI in case of extreme slowness) will have the same result.
Getting the whole console buffer printed out on crash should be top
priority.

[akpm@linux-foundation.org: tweak comment text]
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Baoquan He <bhe@redhat.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Xie XiuQi <xiexiuqi@huawei.com>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      08d78658
    • B
      pidns: fix set/getpriority and ioprio_set/get in PRIO_USER mode · 8639b461
      由 Ben Segall 提交于 
      setpriority(PRIO_USER, 0, x) will change the priority of tasks outside of
the current pid namespace.  This is in contrast to both the other modes of
setpriority and the example of kill(-1).  Fix this.  getpriority and
ioprio have the same failure mode, fix them too.

Eric said:

: After some more thinking about it this patch sounds justifiable.
:
: My goal with namespaces is not to build perfect isolation mechanisms
: as that can get into ill defined territory, but to build well defined
: mechanisms.  And to handle the corner cases so you can use only
: a single namespace with well defined results.
:
: In this case you have found the two interfaces I am aware of that
: identify processes by uid instead of by pid.  Which quite frankly is
: weird.  Unfortunately the weird unexpected cases are hard to handle
: in the usual way.
:
: I was hoping for a little more information.  Changes like this one we
: have to be careful of because someone might be depending on the current
: behavior.  I don't think they are and I do think this make sense as part
: of the pid namespace.
Signed-off-by: NBen Segall <bsegall@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ambrose Feinstein <ambrose@google.com>
Acked-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      8639b461
    • M
      kexec: use file name as the output message prefix · de90a6bc
      由 Minfei Huang 提交于 
      kexec output message misses the prefix "kexec", when Dave Young split the
kexec code.  Now, we use file name as the output message prefix.

Currently, the format of output message:
[  140.290795] SYSC_kexec_load: hello, world
[  140.291534] kexec: sanity_check_segment_list: hello, world

Ideally, the format of output message:
[   30.791503] kexec: SYSC_kexec_load, Hello, world
[   79.182752] kexec_core: sanity_check_segment_list, Hello, world

Remove the custom prefix "kexec" in output message.
Signed-off-by: NMinfei Huang <mnfhuang@gmail.com>
Acked-by: NDave Young <dyoung@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      de90a6bc
    • O
      coredump: ensure all coredumping tasks have SIGNAL_GROUP_COREDUMP · 5fa534c9
      由 Oleg Nesterov 提交于 
      task_will_free_mem() is wrong in many ways, and in particular the
SIGNAL_GROUP_COREDUMP check is not reliable: a task can participate in the
coredumping without SIGNAL_GROUP_COREDUMP bit set.

change zap_threads() paths to always set SIGNAL_GROUP_COREDUMP even if
other CLONE_VM processes can't react to SIGKILL.  Fortunately, at least
oom-kill case if fine; it kills all tasks sharing the same mm, so it
should also kill the process which actually dumps the core.

The change in prepare_signal() is not strictly necessary, it just ensures
that the patch does not bring another subtle behavioural change.  But it
reminds us that this SIGNAL_GROUP_EXIT/COREDUMP case needs more changes.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Kyle Walker <kwalker@redhat.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Stanislav Kozina <skozina@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      5fa534c9
    • O
      signals: kill block_all_signals() and unblock_all_signals() · 2e01fabe
      由 Oleg Nesterov 提交于 
      It is hardly possible to enumerate all problems with block_all_signals()
and unblock_all_signals().  Just for example,

1. block_all_signals(SIGSTOP/etc) simply can't help if the caller is
   multithreaded. Another thread can dequeue the signal and force the
   group stop.

2. Even is the caller is single-threaded, it will "stop" anyway. It
   will not sleep, but it will spin in kernel space until SIGCONT or
   SIGKILL.

And a lot more. In short, this interface doesn't work at all, at least
the last 10+ years.

Daniel said:

  Yeah the only times I played around with the DRM_LOCK stuff was when
  old drivers accidentally deadlocked - my impression is that the entire
  DRM_LOCK thing was never really tested properly ;-) Hence I'm all for
  purging where this leaks out of the drm subsystem.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: NDave Airlie <airlied@redhat.com>
Cc: Richard Weinberger <richard@nod.at>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      2e01fabe
    • M
      printk: prevent userland from spoofing kernel messages · 3824657c
      由 Mathias Krause 提交于 
      The following statement of ABI/testing/dev-kmsg is not quite right:

   It is not possible to inject messages from userspace with the
   facility number LOG_KERN (0), to make sure that the origin of the
   messages can always be reliably determined.

Userland actually can inject messages with a facility of 0 by abusing the
fact that the facility is stored in a u8 data type.  By using a facility
which is a multiple of 256 the assignment of msg->facility in log_store()
implicitly truncates it to 0, i.e.  LOG_KERN, allowing users of /dev/kmsg
to spoof kernel messages as shown below:

The following call...
   # printf '<%d>Kernel panic - not syncing: beer empty\n' 0 >/dev/kmsg
...leads to the following log entry (dmesg -x | tail -n 1):
   user  :emerg : [   66.137758] Kernel panic - not syncing: beer empty

However, this call...
   # printf '<%d>Kernel panic - not syncing: beer empty\n' 0x800 >/dev/kmsg
...leads to the slightly different log entry (note the kernel facility):
   kern  :emerg : [   74.177343] Kernel panic - not syncing: beer empty

Fix that by limiting the user provided facility to 8 bit right from the
beginning and catch the truncation early.

Fixes: 7ff9554b ("printk: convert byte-buffer to variable-length...")
Signed-off-by: NMathias Krause <minipli@googlemail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Petr Mladek <pmladek@suse.cz>
Cc: Alex Elder <elder@linaro.org>
Cc: Joe Perches <joe@perches.com>
Cc: Kay Sievers <kay@vrfy.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      3824657c
    • D
      module: export param_free_charp() · 3d9c637f
      由 Dan Streetman 提交于 
      Change the param_free_charp() function from static to exported.

It is used by zswap in the next patch ("zswap: use charp for zswap param
strings").
Signed-off-by: NDan Streetman <ddstreet@ieee.org>
Acked-by: NRusty Russell <rusty@rustcorp.com.au>
Cc: Seth Jennings <sjennings@variantweb.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      3d9c637f
    • M
      mm, page_alloc: rename __GFP_WAIT to __GFP_RECLAIM · 71baba4b
      由 Mel Gorman 提交于 
      __GFP_WAIT was used to signal that the caller was in atomic context and
could not sleep.  Now it is possible to distinguish between true atomic
context and callers that are not willing to sleep.  The latter should
clear __GFP_DIRECT_RECLAIM so kswapd will still wake.  As clearing
__GFP_WAIT behaves differently, there is a risk that people will clear the
wrong flags.  This patch renames __GFP_WAIT to __GFP_RECLAIM to clearly
indicate what it does -- setting it allows all reclaim activity, clearing
them prevents it.

[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      71baba4b
    • M
      mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep... · d0164adc
      由 Mel Gorman 提交于 
      mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd

__GFP_WAIT has been used to identify atomic context in callers that hold
spinlocks or are in interrupts.  They are expected to be high priority and
have access one of two watermarks lower than "min" which can be referred
to as the "atomic reserve".  __GFP_HIGH users get access to the first
lower watermark and can be called the "high priority reserve".

Over time, callers had a requirement to not block when fallback options
were available.  Some have abused __GFP_WAIT leading to a situation where
an optimisitic allocation with a fallback option can access atomic
reserves.

This patch uses __GFP_ATOMIC to identify callers that are truely atomic,
cannot sleep and have no alternative.  High priority users continue to use
__GFP_HIGH.  __GFP_DIRECT_RECLAIM identifies callers that can sleep and
are willing to enter direct reclaim.  __GFP_KSWAPD_RECLAIM to identify
callers that want to wake kswapd for background reclaim.  __GFP_WAIT is
redefined as a caller that is willing to enter direct reclaim and wake
kswapd for background reclaim.

This patch then converts a number of sites

o __GFP_ATOMIC is used by callers that are high priority and have memory
  pools for those requests. GFP_ATOMIC uses this flag.

o Callers that have a limited mempool to guarantee forward progress clear
  __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall
  into this category where kswapd will still be woken but atomic reserves
  are not used as there is a one-entry mempool to guarantee progress.

o Callers that are checking if they are non-blocking should use the
  helper gfpflags_allow_blocking() where possible. This is because
  checking for __GFP_WAIT as was done historically now can trigger false
  positives. Some exceptions like dm-crypt.c exist where the code intent
  is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to
  flag manipulations.

o Callers that built their own GFP flags instead of starting with GFP_KERNEL
  and friends now also need to specify __GFP_KSWAPD_RECLAIM.

The first key hazard to watch out for is callers that removed __GFP_WAIT
and was depending on access to atomic reserves for inconspicuous reasons.
In some cases it may be appropriate for them to use __GFP_HIGH.

The second key hazard is callers that assembled their own combination of
GFP flags instead of starting with something like GFP_KERNEL.  They may
now wish to specify __GFP_KSWAPD_RECLAIM.  It's almost certainly harmless
if it's missed in most cases as other activity will wake kswapd.
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      d0164adc
  17. 06 11月, 2015 16 次提交
  19. 05 11月, 2015 1 次提交
    • T
      timers: Use proper base migration in add_timer_on() · 22b886dd
      由 Tejun Heo 提交于 
      Regardless of the previous CPU a timer was on, add_timer_on()
currently simply sets timer->flags to the new CPU.  As the caller must
be seeing the timer as idle, this is locally fine, but the timer
leaving the old base while unlocked can lead to race conditions as
follows.

Let's say timer was on cpu 0.

  cpu 0					cpu 1
  -----------------------------------------------------------------------------
  del_timer(timer) succeeds
					del_timer(timer)
					  lock_timer_base(timer) locks cpu_0_base
  add_timer_on(timer, 1)
    spin_lock(&cpu_1_base->lock)
    timer->flags set to cpu_1_base
    operates on @timer			  operates on @timer

This triggered with mod_delayed_work_on() which contains
"if (del_timer()) add_timer_on()" sequence eventually leading to the
following oops.

  BUG: unable to handle kernel NULL pointer dereference at           (null)
  IP: [<ffffffff810ca6e9>] detach_if_pending+0x69/0x1a0
  ...
  Workqueue: wqthrash wqthrash_workfunc [wqthrash]
  task: ffff8800172ca680 ti: ffff8800172d0000 task.ti: ffff8800172d0000
  RIP: 0010:[<ffffffff810ca6e9>]  [<ffffffff810ca6e9>] detach_if_pending+0x69/0x1a0
  ...
  Call Trace:
   [<ffffffff810cb0b4>] del_timer+0x44/0x60
   [<ffffffff8106e836>] try_to_grab_pending+0xb6/0x160
   [<ffffffff8106e913>] mod_delayed_work_on+0x33/0x80
   [<ffffffffa0000081>] wqthrash_workfunc+0x61/0x90 [wqthrash]
   [<ffffffff8106dba8>] process_one_work+0x1e8/0x650
   [<ffffffff8106e05e>] worker_thread+0x4e/0x450
   [<ffffffff810746af>] kthread+0xef/0x110
   [<ffffffff8185980f>] ret_from_fork+0x3f/0x70

Fix it by updating add_timer_on() to perform proper migration as
__mod_timer() does.
Reported-and-tested-by: NJeff Layton <jlayton@poochiereds.net>
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Chris Worley <chris.worley@primarydata.com>
Cc: bfields@fieldses.org
Cc: Michael Skralivetsky <michael.skralivetsky@primarydata.com>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: Shaohua Li <shli@fb.com>
Cc: Jeff Layton <jlayton@poochiereds.net>
Cc: kernel-team@fb.com
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20151029103113.2f893924@tlielax.poochiereds.net
Link: http://lkml.kernel.org/r/20151104171533.GI5749@mtj.duckdns.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      22b886dd