<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/kernel, branch v4.1-rc8</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2015-06-15T00:03:11+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2015-06-15T00:03:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=5bd2c2867ffc0f4beeac5b94b0f674969f24c883'/>
<id>5bd2c2867ffc0f4beeac5b94b0f674969f24c883</id>
<content type='text'>
Pull lockdep fix from Ingo Molnar:
 "A lockdep/modules unload race fix that can oops"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  lockdep: Fix a race between /proc/lock_stat and module unload
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull lockdep fix from Ingo Molnar:
 "A lockdep/modules unload race fix that can oops"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  lockdep: Fix a race between /proc/lock_stat and module unload
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'trace-rb-bm-fix-4.1-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace</title>
<updated>2015-06-11T21:00:10+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2015-06-11T21:00:10+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=cff100f5d746465ca40e61cf296321ecf07d3f1c'/>
<id>cff100f5d746465ca40e61cf296321ecf07d3f1c</id>
<content type='text'>
Pull ring buffer benchmark buglet fix from Steven Rostedt:
 "Wang Long fixed a minor bug in the module parameter for the ring
  buffer benchmark, where the produce_fifo was being ignored and the
  producer thread's priority was being set with the consumer_fifo
  parameter"

* tag 'trace-rb-bm-fix-4.1-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ring-buffer-benchmark: Fix the wrong sched_priority of producer
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull ring buffer benchmark buglet fix from Steven Rostedt:
 "Wang Long fixed a minor bug in the module parameter for the ring
  buffer benchmark, where the produce_fifo was being ignored and the
  producer thread's priority was being set with the consumer_fifo
  parameter"

* tag 'trace-rb-bm-fix-4.1-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ring-buffer-benchmark: Fix the wrong sched_priority of producer
</pre>
</div>
</content>
</entry>
<entry>
<title>ring-buffer-benchmark: Fix the wrong sched_priority of producer</title>
<updated>2015-06-11T13:27:58+00:00</updated>
<author>
<name>Wang Long</name>
<email>long.wanglong@huawei.com</email>
</author>
<published>2015-06-10T08:12:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=108029323910c5dd1ef8fa2d10da1ce5fbce6e12'/>
<id>108029323910c5dd1ef8fa2d10da1ce5fbce6e12</id>
<content type='text'>
The producer should be used producer_fifo as its sched_priority,
so correct it.

Link: http://lkml.kernel.org/r/1433923957-67842-1-git-send-email-long.wanglong@huawei.com

Cc: stable@vger.kernel.org # 2.6.33+
Signed-off-by: Wang Long &lt;long.wanglong@huawei.com&gt;
Signed-off-by: Steven Rostedt &lt;rostedt@goodmis.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The producer should be used producer_fifo as its sched_priority,
so correct it.

Link: http://lkml.kernel.org/r/1433923957-67842-1-git-send-email-long.wanglong@huawei.com

Cc: stable@vger.kernel.org # 2.6.33+
Signed-off-by: Wang Long &lt;long.wanglong@huawei.com&gt;
Signed-off-by: Steven Rostedt &lt;rostedt@goodmis.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched, numa: do not hint for NUMA balancing on VM_MIXEDMAP mappings</title>
<updated>2015-06-10T23:43:43+00:00</updated>
<author>
<name>Mel Gorman</name>
<email>mgorman@suse.de</email>
</author>
<published>2015-06-10T18:15:00+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=8e76d4eecf7afeec9328e21cd5880e281838d0d6'/>
<id>8e76d4eecf7afeec9328e21cd5880e281838d0d6</id>
<content type='text'>
Jovi Zhangwei reported the following problem

  Below kernel vm bug can be triggered by tcpdump which mmaped a lot of pages
  with GFP_COMP flag.

  [Mon May 25 05:29:33 2015] page:ffffea0015414000 count:66 mapcount:1 mapping:          (null) index:0x0
  [Mon May 25 05:29:33 2015] flags: 0x20047580004000(head)
  [Mon May 25 05:29:33 2015] page dumped because: VM_BUG_ON_PAGE(compound_order(page) &amp;&amp; !PageTransHuge(page))
  [Mon May 25 05:29:33 2015] ------------[ cut here ]------------
  [Mon May 25 05:29:33 2015] kernel BUG at mm/migrate.c:1661!
  [Mon May 25 05:29:33 2015] invalid opcode: 0000 [#1] SMP

In this case it was triggered by running tcpdump but it's not necessary
reproducible on all systems.

  sudo tcpdump -i bond0.100 'tcp port 4242' -c 100000000000 -w 4242.pcap

Compound pages cannot be migrated and it was not expected that such pages
be marked for NUMA balancing.  This did not take into account that drivers
such as net/packet/af_packet.c may insert compound pages into userspace
with vm_insert_page.  This patch tells the NUMA balancing protection
scanner to skip all VM_MIXEDMAP mappings which avoids the possibility that
compound pages are marked for migration.

Signed-off-by: Mel Gorman &lt;mgorman@suse.de&gt;
Reported-by: Jovi Zhangwei &lt;jovi@cloudflare.com&gt;
Cc: Ingo Molnar &lt;mingo@elte.hu&gt;
Cc: Peter Zijlstra &lt;a.p.zijlstra@chello.nl&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Jovi Zhangwei reported the following problem

  Below kernel vm bug can be triggered by tcpdump which mmaped a lot of pages
  with GFP_COMP flag.

  [Mon May 25 05:29:33 2015] page:ffffea0015414000 count:66 mapcount:1 mapping:          (null) index:0x0
  [Mon May 25 05:29:33 2015] flags: 0x20047580004000(head)
  [Mon May 25 05:29:33 2015] page dumped because: VM_BUG_ON_PAGE(compound_order(page) &amp;&amp; !PageTransHuge(page))
  [Mon May 25 05:29:33 2015] ------------[ cut here ]------------
  [Mon May 25 05:29:33 2015] kernel BUG at mm/migrate.c:1661!
  [Mon May 25 05:29:33 2015] invalid opcode: 0000 [#1] SMP

In this case it was triggered by running tcpdump but it's not necessary
reproducible on all systems.

  sudo tcpdump -i bond0.100 'tcp port 4242' -c 100000000000 -w 4242.pcap

Compound pages cannot be migrated and it was not expected that such pages
be marked for NUMA balancing.  This did not take into account that drivers
such as net/packet/af_packet.c may insert compound pages into userspace
with vm_insert_page.  This patch tells the NUMA balancing protection
scanner to skip all VM_MIXEDMAP mappings which avoids the possibility that
compound pages are marked for migration.

Signed-off-by: Mel Gorman &lt;mgorman@suse.de&gt;
Reported-by: Jovi Zhangwei &lt;jovi@cloudflare.com&gt;
Cc: Ingo Molnar &lt;mingo@elte.hu&gt;
Cc: Peter Zijlstra &lt;a.p.zijlstra@chello.nl&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>lockdep: Fix a race between /proc/lock_stat and module unload</title>
<updated>2015-06-07T13:46:30+00:00</updated>
<author>
<name>Peter Zijlstra</name>
<email>peterz@infradead.org</email>
</author>
<published>2015-06-02T10:50:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=cee34d88cabd1ba5fc93e09b5b12232bc9338c7c'/>
<id>cee34d88cabd1ba5fc93e09b5b12232bc9338c7c</id>
<content type='text'>
The lock_class iteration of /proc/lock_stat is not serialized against
the lockdep_free_key_range() call from module unload.

Therefore it can happen that we find a class of which -&gt;name/-&gt;key are
no longer valid.

There is a further bug in zap_class() that left -&gt;name dangling. Cure
this. Use RCU_INIT_POINTER() because NULL.

Since lockdep_free_key_range() is rcu_sched serialized, we can read
both -&gt;name and -&gt;key under rcu_read_lock_sched() (preempt-disable)
and be assured that if we observe a !NULL value it stays safe to use
for as long as we hold that lock.

If we observe both NULL, skip the entry.

Reported-by: Jerome Marchand &lt;jmarchan@redhat.com&gt;
Tested-by: Jerome Marchand &lt;jmarchan@redhat.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: H. Peter Anvin &lt;hpa@zytor.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Link: http://lkml.kernel.org/r/20150602105013.GS3644@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The lock_class iteration of /proc/lock_stat is not serialized against
the lockdep_free_key_range() call from module unload.

Therefore it can happen that we find a class of which -&gt;name/-&gt;key are
no longer valid.

There is a further bug in zap_class() that left -&gt;name dangling. Cure
this. Use RCU_INIT_POINTER() because NULL.

Since lockdep_free_key_range() is rcu_sched serialized, we can read
both -&gt;name and -&gt;key under rcu_read_lock_sched() (preempt-disable)
and be assured that if we observe a !NULL value it stays safe to use
for as long as we hold that lock.

If we observe both NULL, skip the entry.

Reported-by: Jerome Marchand &lt;jmarchan@redhat.com&gt;
Tested-by: Jerome Marchand &lt;jmarchan@redhat.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: H. Peter Anvin &lt;hpa@zytor.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Link: http://lkml.kernel.org/r/20150602105013.GS3644@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2015-06-05T17:00:53+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2015-06-05T17:00:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=a0e9c6efa585897f00eb22e67887e5a25482b1b8'/>
<id>a0e9c6efa585897f00eb22e67887e5a25482b1b8</id>
<content type='text'>
Pull perf fixes from Ingo Molnar:
 "The biggest chunk of the changes are two regression fixes: a HT
  workaround fix and an event-group scheduling fix.  It's been verified
  with 5 days of fuzzer testing.

  Other fixes:

   - eBPF fix
   - a BIOS breakage detection fix
   - PMU driver fixes"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/intel/pt: Fix a refactoring bug
  perf/x86: Tweak broken BIOS rules during check_hw_exists()
  perf/x86/intel/pt: Untangle pt_buffer_reset_markers()
  perf: Disallow sparse AUX allocations for non-SG PMUs in overwrite mode
  perf/x86: Improve HT workaround GP counter constraint
  perf/x86: Fix event/group validation
  perf: Fix race in BPF program unregister
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull perf fixes from Ingo Molnar:
 "The biggest chunk of the changes are two regression fixes: a HT
  workaround fix and an event-group scheduling fix.  It's been verified
  with 5 days of fuzzer testing.

  Other fixes:

   - eBPF fix
   - a BIOS breakage detection fix
   - PMU driver fixes"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/intel/pt: Fix a refactoring bug
  perf/x86: Tweak broken BIOS rules during check_hw_exists()
  perf/x86/intel/pt: Untangle pt_buffer_reset_markers()
  perf: Disallow sparse AUX allocations for non-SG PMUs in overwrite mode
  perf/x86: Improve HT workaround GP counter constraint
  perf/x86: Fix event/group validation
  perf: Fix race in BPF program unregister
</pre>
</div>
</content>
</entry>
<entry>
<title>compat: cleanup coding in compat_get_bitmap() and compat_put_bitmap()</title>
<updated>2015-06-04T21:57:18+00:00</updated>
<author>
<name>Helge Deller</name>
<email>deller@gmx.de</email>
</author>
<published>2015-06-04T21:57:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=9b7b819ca1e508195feed5ece558dca66adeef05'/>
<id>9b7b819ca1e508195feed5ece558dca66adeef05</id>
<content type='text'>
In the functions compat_get_bitmap() and compat_put_bitmap() the
variable nr_compat_longs stores how many compat_ulong_t words should be
copied in a loop.

The copy loop itself is this:
  if (nr_compat_longs-- &gt; 0) {
      if (__get_user(um, umask)) return -EFAULT;
  } else {
      um = 0;
  }

Since nr_compat_longs gets unconditionally decremented in each loop and
since it's type is unsigned this could theoretically lead to out of
bounds accesses to userspace if nr_compat_longs wraps around to
(unsigned)(-1).

Although the callers currently do not trigger out-of-bounds accesses, we
should better implement the loop in a safe way to completely avoid such
warp-arounds.

Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In the functions compat_get_bitmap() and compat_put_bitmap() the
variable nr_compat_longs stores how many compat_ulong_t words should be
copied in a loop.

The copy loop itself is this:
  if (nr_compat_longs-- &gt; 0) {
      if (__get_user(um, umask)) return -EFAULT;
  } else {
      um = 0;
  }

Since nr_compat_longs gets unconditionally decremented in each loop and
since it's type is unsigned this could theoretically lead to out of
bounds accesses to userspace if nr_compat_longs wraps around to
(unsigned)(-1).

Although the callers currently do not trigger out-of-bounds accesses, we
should better implement the loop in a safe way to completely avoid such
warp-arounds.

Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux</title>
<updated>2015-05-29T18:24:28+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2015-05-29T18:24:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=6e49ba1bb1deddd2da806284a37e7f3d3d711301'/>
<id>6e49ba1bb1deddd2da806284a37e7f3d3d711301</id>
<content type='text'>
Pull fixes for cpumask and modules from Rusty Russell:
 "** NOW WITH TESTING! **

  Two fixes which got lost in my recent distraction.  One is a weird
  cpumask function which needed to be rewritten, the other is a module
  bug which is cc:stable"

* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
  cpumask_set_cpu_local_first =&gt; cpumask_local_spread, lament
  module: Call module notifier on failure after complete_formation()
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull fixes for cpumask and modules from Rusty Russell:
 "** NOW WITH TESTING! **

  Two fixes which got lost in my recent distraction.  One is a weird
  cpumask function which needed to be rewritten, the other is a module
  bug which is cc:stable"

* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
  cpumask_set_cpu_local_first =&gt; cpumask_local_spread, lament
  module: Call module notifier on failure after complete_formation()
</pre>
</div>
</content>
</entry>
<entry>
<title>perf: Disallow sparse AUX allocations for non-SG PMUs in overwrite mode</title>
<updated>2015-05-27T07:16:20+00:00</updated>
<author>
<name>Alexander Shishkin</name>
<email>alexander.shishkin@linux.intel.com</email>
</author>
<published>2015-05-22T15:30:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=aa319bcd366349c6f72fcd331da89d3d06090651'/>
<id>aa319bcd366349c6f72fcd331da89d3d06090651</id>
<content type='text'>
PMUs that don't support hardware scatter tables require big contiguous
chunks of memory and a PMI to switch between them. However, in overwrite
using a PMI for this purpose adds extra overhead that the users would
like to avoid. Thus, in overwrite mode for such PMUs we can only allow
one contiguous chunk for the entire requested buffer.

This patch changes the behavior accordingly, so that if the buddy allocator
fails to come up with a single high-order chunk for the entire requested
buffer, the allocation will fail.

Signed-off-by: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: acme@infradead.org
Cc: adrian.hunter@intel.com
Cc: hpa@zytor.com
Link: http://lkml.kernel.org/r/1432308626-18845-2-git-send-email-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
PMUs that don't support hardware scatter tables require big contiguous
chunks of memory and a PMI to switch between them. However, in overwrite
using a PMI for this purpose adds extra overhead that the users would
like to avoid. Thus, in overwrite mode for such PMUs we can only allow
one contiguous chunk for the entire requested buffer.

This patch changes the behavior accordingly, so that if the buddy allocator
fails to come up with a single high-order chunk for the entire requested
buffer, the allocation will fail.

Signed-off-by: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: acme@infradead.org
Cc: adrian.hunter@intel.com
Cc: hpa@zytor.com
Link: http://lkml.kernel.org/r/1432308626-18845-2-git-send-email-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf: Fix race in BPF program unregister</title>
<updated>2015-05-27T06:46:15+00:00</updated>
<author>
<name>Alexei Starovoitov</name>
<email>ast@plumgrid.com</email>
</author>
<published>2015-05-15T19:15:21+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=dead9f29ddcc69551f35529a252d2704047870d3'/>
<id>dead9f29ddcc69551f35529a252d2704047870d3</id>
<content type='text'>
there is a race between perf_event_free_bpf_prog() and free_trace_kprobe():

	__free_event()
	  event-&gt;destroy(event)
	    tp_perf_event_destroy()
	      perf_trace_destroy()
		perf_trace_event_unreg()

which is dropping event-&gt;tp_event-&gt;perf_refcount and allows to proceed in:

	unregister_trace_kprobe()
	  unregister_kprobe_event()
	      trace_remove_event_call()
		    probe_remove_event_call()
	free_trace_kprobe()

while __free_event does:

	call_rcu(&amp;event-&gt;rcu_head, free_event_rcu);
	  free_event_rcu()
	    perf_event_free_bpf_prog()

To fix the race simply move perf_event_free_bpf_prog() before
event-&gt;destroy(), since event-&gt;tp_event is still valid at that point.

Note, perf_trace_destroy() is not racing with trace_remove_event_call()
since they both grab event_mutex.

Reported-by: Wang Nan &lt;wangnan0@huawei.com&gt;
Signed-off-by: Alexei Starovoitov &lt;ast@plumgrid.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@infradead.org&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: lizefan@huawei.com
Cc: pi3orama@163.com
Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes")
Link: http://lkml.kernel.org/r/1431717321-28772-1-git-send-email-ast@plumgrid.com
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
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<pre>
there is a race between perf_event_free_bpf_prog() and free_trace_kprobe():

	__free_event()
	  event-&gt;destroy(event)
	    tp_perf_event_destroy()
	      perf_trace_destroy()
		perf_trace_event_unreg()

which is dropping event-&gt;tp_event-&gt;perf_refcount and allows to proceed in:

	unregister_trace_kprobe()
	  unregister_kprobe_event()
	      trace_remove_event_call()
		    probe_remove_event_call()
	free_trace_kprobe()

while __free_event does:

	call_rcu(&amp;event-&gt;rcu_head, free_event_rcu);
	  free_event_rcu()
	    perf_event_free_bpf_prog()

To fix the race simply move perf_event_free_bpf_prog() before
event-&gt;destroy(), since event-&gt;tp_event is still valid at that point.

Note, perf_trace_destroy() is not racing with trace_remove_event_call()
since they both grab event_mutex.

Reported-by: Wang Nan &lt;wangnan0@huawei.com&gt;
Signed-off-by: Alexei Starovoitov &lt;ast@plumgrid.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@infradead.org&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: lizefan@huawei.com
Cc: pi3orama@163.com
Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes")
Link: http://lkml.kernel.org/r/1431717321-28772-1-git-send-email-ast@plumgrid.com
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</pre>
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