linux-stable.git/kernel/printk, branch linux-4.17.y

printk: drop in_nmi check from printk_safe_flush_on_panic()

2018-08-03T05:47:36+00:00

[ Upstream commit 554755be08fba31c74f66b82a485e5513205af84 ]

Drop the in_nmi() check from printk_safe_flush_on_panic()
and attempt to re-init (IOW unlock) locked logbuf spinlock
from panic CPU regardless of its context.

Otherwise, theoretically, we can deadlock on logbuf trying to flush
per-CPU buffers:

  a) Panic CPU is running in non-NMI context
  b) Panic CPU sends out shutdown IPI via reboot vector
  c) Panic CPU fails to stop all remote CPUs
  d) Panic CPU sends out shutdown IPI via NMI vector
     One of the CPUs that we bring down via NMI vector can hold
     logbuf spin lock (theoretically).

Link: http://lkml.kernel.org/r/20180530070350.10131-1-sergey.senozhatsky@gmail.com
To: Steven Rostedt 
Cc: Peter Zijlstra 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Sergey Senozhatsky 
Signed-off-by: Petr Mladek 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

printk: fix possible reuse of va_list variable

2018-07-03T09:26:49+00:00

commit 988a35f8da1dec5a8cd2788054d1e717be61bf25 upstream.

I noticed that there is a possibility that printk_safe_log_store() causes
kernel oops because "args" parameter is passed to vsnprintf() again when
atomic_cmpxchg() detected that we raced. Fix this by using va_copy().

Link: http://lkml.kernel.org/r/201805112002.GIF21216.OFVHFOMLJtQFSO@I-love.SAKURA.ne.jp
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: dvyukov@google.com
Cc: syzkaller@googlegroups.com
Cc: fengguang.wu@intel.com
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Tetsuo Handa 
Fixes: 42a0bb3f71383b45 ("printk/nmi: generic solution for safe printk in NMI")
Cc: 4.7+  # v4.7+
Reviewed-by: Sergey Senozhatsky 
Signed-off-by: Petr Mladek 
Signed-off-by: Greg Kroah-Hartman

Merge tag 'trace-v4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2018-04-10T18:27:30+00:00

Pull tracing updates from Steven Rostedt:
 "New features:

   - Tom Zanussi's extended histogram work.

     This adds the synthetic events to have histograms from multiple
     event data Adds triggers "onmatch" and "onmax" to call the
     synthetic events Several updates to the histogram code from this

   - Allow way to nest ring buffer calls in the same context

   - Allow absolute time stamps in ring buffer

   - Rewrite of filter code parsing based on Al Viro's suggestions

   - Setting of trace_clock to global if TSC is unstable (on boot)

   - Better OOM handling when allocating large ring buffers

   - Added initcall tracepoints (consolidated initcall_debug code with
     them)

  And other various fixes and clean ups"

* tag 'trace-v4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (68 commits)
  init: Have initcall_debug still work without CONFIG_TRACEPOINTS
  init, tracing: Have printk come through the trace events for initcall_debug
  init, tracing: instrument security and console initcall trace events
  init, tracing: Add initcall trace events
  tracing: Add rcu dereference annotation for test func that touches filter->prog
  tracing: Add rcu dereference annotation for filter->prog
  tracing: Fixup logic inversion on setting trace_global_clock defaults
  tracing: Hide global trace clock from lockdep
  ring-buffer: Add set/clear_current_oom_origin() during allocations
  ring-buffer: Check if memory is available before allocation
  lockdep: Add print_irqtrace_events() to __warn
  vsprintf: Do not preprocess non-dereferenced pointers for bprintf (%px and %pK)
  tracing: Uninitialized variable in create_tracing_map_fields()
  tracing: Make sure variable string fields are NULL-terminated
  tracing: Add action comparisons when testing matching hist triggers
  tracing: Don't add flag strings when displaying variable references
  tracing: Fix display of hist trigger expressions containing timestamps
  ftrace: Drop a VLA in module_exists()
  tracing: Mention trace_clock=global when warning about unstable clocks
  tracing: Default to using trace_global_clock if sched_clock is unstable
  ...

init, tracing: instrument security and console initcall trace events

2018-04-06T12:56:55+00:00

Trace events have been added around the initcall functions defined in
init/main.c. But console and security have their own initcalls. This adds
the trace events associated for those initcall functions.

Link: http://lkml.kernel.org/r/1521765208.19745.2.camel@polymtl.ca

Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Signed-off-by: Abderrahmane Benbachir 
Signed-off-by: Steven Rostedt (VMware)

Merge branch 'for-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk

2018-04-06T02:53:30+00:00

Pull printk updates from Petr Mladek:

 - Add info about loaded kdump kernel into the dump stack header

 - Move dump-stack related code from printk.c to lib/dump_stack.c

 - Write message about suspending consoles in KERN_INFO log level

* 'for-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk:
  printk: change message to pr_info
  printk: move dump stack related code to lib/dump_stack.c
  print kdump kernel loaded status in stack dump

printk: change message to pr_info

2018-03-23T14:41:59+00:00

To allow userspace to prevent this message from appearing in the
console by changing the log priority.

This matches other informative messages that the power subsystem emits
when the system changes power states.

Link: http://lkml.kernel.org/r/20180322135833.16602-1-tomeu.vizoso@collabora.com
To: linux-kernel@vger.kernel.org
Cc: kernel@collabora.com
Cc: Steven Rostedt 
Signed-off-by: Tomeu Vizoso 
Reviewed-by: Sergey Senozhatsky 
Signed-off-by: Petr Mladek

printk: move dump stack related code to lib/dump_stack.c

2018-03-15T12:25:36+00:00

dump_stack related stuff should belong to lib/dump_stack.c thus move them
there. Also conditionally compile lib/dump_stack.c since dump_stack code
does not make sense if printk is disabled.

Link: http://lkml.kernel.org/r/20180213072834.GA24784@dhcp-128-65.nay.redhat.com
To: Steven Rostedt 
Cc: linux-kernel@vger.kernel.org
Cc: akpm@linux-foundation.org
Cc: Andi Kleen 
Signed-off-by: Dave Young 
Suggested-by: Steven Rostedt 
Suggested-by: Sergey Senozhatsky 
Reviewed-by: Sergey Senozhatsky 
Signed-off-by: Petr Mladek

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

2018-03-01T18:06:39+00:00

Pull printk fix from Petr Mladek:
 "Make sure that we wake up userspace loggers. This fixes a race
  introduced by the console waiter logic during this merge window"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk:
  printk: Wake klogd when passing console_lock owner

printk: Wake klogd when passing console_lock owner

2018-02-27T09:25:50+00:00

wake_klogd is a local variable in console_unlock(). The information
is lost when the console_lock owner using the busy wait added by
the commit dbdda842fe96f8932 ("printk: Add console owner and waiter
logic to load balance console writes"). The following race is
possible:

CPU0				CPU1
console_unlock()

  for (;;)
     /* calling console for last message */

				printk()
				  log_store()
				    log_next_seq++;

     /* see new message */
     if (seen_seq != log_next_seq) {
	wake_klogd = true;
	seen_seq = log_next_seq;
     }

     console_lock_spinning_enable();

				  if (console_trylock_spinning())
				     /* spinning */

     if (console_lock_spinning_disable_and_check()) {
	printk_safe_exit_irqrestore(flags);
	return;

				  console_unlock()
				    if (seen_seq != log_next_seq) {
				    /* already seen */
				    /* nothing to do */

Result: Nobody would wakeup klogd.

One solution would be to make a global variable from wake_klogd.
But then we would need to manipulate it under a lock or so.

This patch wakes klogd also when console_lock is passed to the
spinning waiter. It looks like the right way to go. Also userspace
should have a chance to see and store any "flood" of messages.

Note that the very late klogd wake up was a historic solution.
It made sense on single CPU systems or when sys_syslog() operations
were synchronized using the big kernel lock like in v2.1.113.
But it is questionable these days.

Fixes: dbdda842fe96f8932 ("printk: Add console owner and waiter logic to load balance console writes")
Link: http://lkml.kernel.org/r/20180226155734.dzwg3aovqnwtvkoy@pathway.suse.cz
Cc: Steven Rostedt 
Cc: linux-kernel@vger.kernel.org
Cc: Tejun Heo 
Suggested-by: Sergey Senozhatsky 
Reviewed-by: Sergey Senozhatsky 
Signed-off-by: Petr Mladek

vfs: do bulk POLL* -> EPOLL* replacement

2018-02-11T22:34:03+00:00

This is the mindless scripted replacement of kernel use of POLL*
variables as described by Al, done by this script:

    for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do
        L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'`
        for f in $L; do sed -i "-es/^\([^\"]*\)\(\\)/\\1E\\2/" $f; done
    done

with de-mangling cleanups yet to come.

NOTE! On almost all architectures, the EPOLL* constants have the same
values as the POLL* constants do.  But they keyword here is "almost".
For various bad reasons they aren't the same, and epoll() doesn't
actually work quite correctly in some cases due to this on Sparc et al.

The next patch from Al will sort out the final differences, and we
should be all done.

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