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Commit Graph

21523 Commits

Author SHA1 Message Date
Richard Guy Briggs
133e1e5acd audit: stop an old auditd being starved out by a new auditd
Nothing prevents a new auditd starting up and replacing a valid
audit_pid when an old auditd is still running, effectively starving out
the old auditd since audit_pid no longer points to the old valid
auditd.

If no message to auditd has been attempted since auditd died
unnaturally or got killed, audit_pid will still indicate it is alive.
There isn't an easy way to detect if an old auditd is still running on
the existing audit_pid other than attempting to send a message to see
if it fails.  An -ECONNREFUSED almost certainly means it disappeared
and can be replaced.  Other errors are not so straightforward and may
indicate transient problems that will resolve themselves and the old
auditd will recover.  Yet others will likely need manual intervention
for which a new auditd will not solve the problem.

Send a new message type (AUDIT_REPLACE) to the old auditd containing a
u32 with the PID of the new auditd.  If the audit replace message
succeeds (or doesn't fail with certainty), fail to register the new
auditd and return an error (-EEXIST).

This is expected to make the patch preventing an old auditd orphaning a
new auditd redundant.

V3: Switch audit message type from 1000 to 1300 block.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <pmoore@redhat.com>
2016-01-25 18:04:15 -05:00
Markus Elfring
d865e573b8 audit: Delete unnecessary checks before two function calls
The functions consume_skb() and kfree_skb() test whether their argument
is NULL and then return immediately.
Thus the tests around their calls are not needed.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
[PM: tweak patch prefix]
Signed-off-by: Paul Moore <pmoore@redhat.com>
2016-01-13 09:18:55 -05:00
Richard Guy Briggs
1194b994be audit: wake up threads if queue switched from limited to unlimited
If the audit_backlog_limit is changed from a limited value to an
unlimited value (zero) while the queue was overflowed, wake up the
audit_backlog_wait queue to allow those processes to continue.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <pmoore@redhat.com>
2016-01-13 09:18:54 -05:00
Richard Guy Briggs
f48a942926 audit: include auditd's threads in audit_log_start() wait exception
Should auditd spawn threads, allow all members of its thread group to
use the audit_backlog_limit reserves to bypass the queue limits too.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[PM: minor upstream merge tweaks]
Signed-off-by: Paul Moore <pmoore@redhat.com>
2016-01-13 09:15:19 -05:00
Paul Moore
eb8baf6aa3 audit: remove audit_backlog_wait_overflow
It seems much more obvious and readable to simply use "0".

Signed-off-by: Paul Moore <pmoore@redhat.com>
2016-01-13 09:15:18 -05:00
Richard Guy Briggs
c4b7a7755f audit: don't needlessly reset valid wait time
After auditd has recovered from an overflowed queue, the first process
that doesn't use reserves to make it through the queue checks should
reset the audit backlog wait time to the configured value.  After that,
there is no need to keep resetting it.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <pmoore@redhat.com>
2016-01-13 09:15:18 -05:00
Linus Torvalds
de03017958 Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
 "Misc scheduler fixes"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/core: Reset task's lockless wake-queues on fork()
  sched/core: Fix unserialized r-m-w scribbling stuff
  sched/core: Check tgid in is_global_init()
  sched/fair: Fix multiplication overflow on 32-bit systems
2016-01-08 13:57:13 -08:00
Linus Torvalds
3ab6d1ebd5 Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Ingo Molnar:
 "Two core subsystem fixes, plus a handful of tooling fixes"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf: Fix race in swevent hash
  perf: Fix race in perf_event_exec()
  perf list: Robustify event printing routine
  perf list: Add support for PERF_COUNT_SW_BPF_OUT
  perf hists browser: Fix segfault if use symbol filter in cmdline
  perf hists browser: Reset selection when refresh
  perf hists browser: Add NULL pointer check to prevent crash
  perf buildid-list: Fix return value of perf buildid-list -k
  perf buildid-list: Show running kernel build id fix
2016-01-08 13:52:59 -08:00
Linus Torvalds
ea83ae2fb3 Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull irq fix from Ingo Molnar:
 "Fixes a core IRQ subsystem deadlock"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq: Prevent chip buslock deadlock
2016-01-08 13:46:59 -08:00
Linus Torvalds
2626820d83 PeiyangX Qiu reported that if a module fails to load between calling
ftrace_module_init() and do_init_module() that the allocations made
 in ftrace_module_init() will not be freed, resulting in a memory leak.
 
 The solution is to call ftrace_release_mod() on the failing module in
 the fail path befor do_init_module() is called. This will remove any
 allocations made for that module, and nothing if ftrace_module_init()
 wasn't called yet for that module.
 
 Note, once do_init_module() is called, the MODULE_GOING notifiers are
 called for the failed module, which calls into the ftrace code to do the
 proper clean up (basically calling ftrace_release_mod()).
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Merge tag 'trace-v4.4-rc4-4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull ftrace fix from Steven Rostedt:
 "PeiyangX Qiu reported that if a module fails to load between calling
  ftrace_module_init() and do_init_module() that the allocations made in
  ftrace_module_init() will not be freed, resulting in a memory leak.

  The solution is to call ftrace_release_mod() on the failing module in
  the fail path befor do_init_module() is called.  This will remove any
  allocations made for that module, and nothing if ftrace_module_init()
  wasn't called yet for that module.

  Note, once do_init_module() is called, the MODULE_GOING notifiers are
  called for the failed module, which calls into the ftrace code to do
  the proper clean up (basically calling ftrace_release_mod())"

* tag 'trace-v4.4-rc4-4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ftrace/module: Call clean up function when module init fails early
2016-01-07 12:42:22 -08:00
Steven Rostedt (Red Hat)
049fb9bd41 ftrace/module: Call clean up function when module init fails early
If the module init code fails after calling ftrace_module_init() and before
calling do_init_module(), we can suffer from a memory leak. This is because
ftrace_module_init() allocates pages to store the locations that ftrace
hooks are placed in the module text. If do_init_module() fails, it still
calls the MODULE_GOING notifiers which will tell ftrace to do a clean up of
the pages it allocated for the module. But if load_module() fails before
then, the pages allocated by ftrace_module_init() will never be freed.

Call ftrace_release_mod() on the module if load_module() fails before
getting to do_init_module().

Link: http://lkml.kernel.org/r/567CEA31.1070507@intel.com

Reported-by: "Qiu, PeiyangX" <peiyangx.qiu@intel.com>
Fixes: a949ae560a "ftrace/module: Hardcode ftrace_module_init() call into load_module()"
Cc: stable@vger.kernel.org # v2.6.38+
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2016-01-07 12:17:39 -05:00
Sebastian Andrzej Siewior
093e5840ae sched/core: Reset task's lockless wake-queues on fork()
In the following commit:

  7675104990 ("sched: Implement lockless wake-queues")

we gained lockless wake-queues.

The -RT kernel managed to lockup itself with those. There could be multiple
attempts for task X to enqueue it for a wakeup _even_ if task X is already
running.

The reason is that task X could be runnable but not yet on CPU. The the
task performing the wakeup did not leave the CPU it could performe
multiple wakeups.

With the proper timming task X could be running and enqueued for a
wakeup. If this happens while X is performing a fork() then its its
child will have a !NULL `wake_q` member copied.

This is not a problem as long as the child task does not participate in
lockless wakeups :)

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 7675104990 ("sched: Implement lockless wake-queues")
Link: http://lkml.kernel.org/r/20151221171710.GA5499@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-06 11:01:07 +01:00
Andrey Ryabinin
9e0e83a1ec sched/fair: Fix multiplication overflow on 32-bit systems
Make 'r' 64-bit type to avoid overflow in 'r * LOAD_AVG_MAX'
on 32-bit systems:

	UBSAN: Undefined behaviour in kernel/sched/fair.c:2785:18
	signed integer overflow:
	87950 * 47742 cannot be represented in type 'int'

The most likely effect of this bug are bad load average numbers
resulting in weird scheduling. It's also likely that this can
persist for a longer time - until the system goes idle for
a long time so that all load avg numbers get reset.

[ This is the CFS load average metric, not the procfs output, which
  is separate. ]

Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 9d89c257df ("sched/fair: Rewrite runnable load and utilization average tracking")
Link: http://lkml.kernel.org/r/1450097243-30137-1-git-send-email-aryabinin@virtuozzo.com
[ Improved the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-06 11:01:05 +01:00
Peter Zijlstra
12ca6ad2e3 perf: Fix race in swevent hash
There's a race on CPU unplug where we free the swevent hash array
while it can still have events on. This will result in a
use-after-free which is BAD.

Simply do not free the hash array on unplug. This leaves the thing
around and no use-after-free takes place.

When the last swevent dies, we do a for_each_possible_cpu() iteration
anyway to clean these up, at which time we'll free it, so no leakage
will occur.

Reported-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-06 10:52:39 +01:00
Peter Zijlstra
c127449944 perf: Fix race in perf_event_exec()
I managed to tickle this warning:

  [ 2338.884942] ------------[ cut here ]------------
  [ 2338.890112] WARNING: CPU: 13 PID: 35162 at ../kernel/events/core.c:2702 task_ctx_sched_out+0x6b/0x80()
  [ 2338.900504] Modules linked in:
  [ 2338.903933] CPU: 13 PID: 35162 Comm: bash Not tainted 4.4.0-rc4-dirty #244
  [ 2338.911610] Hardware name: Intel Corporation S2600GZ/S2600GZ, BIOS SE5C600.86B.02.02.0002.122320131210 12/23/2013
  [ 2338.923071]  ffffffff81f1468e ffff8807c6457cb8 ffffffff815c680c 0000000000000000
  [ 2338.931382]  ffff8807c6457cf0 ffffffff810c8a56 ffffe8ffff8c1bd0 ffff8808132ed400
  [ 2338.939678]  0000000000000286 ffff880813170380 ffff8808132ed400 ffff8807c6457d00
  [ 2338.947987] Call Trace:
  [ 2338.950726]  [<ffffffff815c680c>] dump_stack+0x4e/0x82
  [ 2338.956474]  [<ffffffff810c8a56>] warn_slowpath_common+0x86/0xc0
  [ 2338.963195]  [<ffffffff810c8b4a>] warn_slowpath_null+0x1a/0x20
  [ 2338.969720]  [<ffffffff811a49cb>] task_ctx_sched_out+0x6b/0x80
  [ 2338.976244]  [<ffffffff811a62d2>] perf_event_exec+0xe2/0x180
  [ 2338.982575]  [<ffffffff8121fb6f>] setup_new_exec+0x6f/0x1b0
  [ 2338.988810]  [<ffffffff8126de83>] load_elf_binary+0x393/0x1660
  [ 2338.995339]  [<ffffffff811dc772>] ? get_user_pages+0x52/0x60
  [ 2339.001669]  [<ffffffff8121e297>] search_binary_handler+0x97/0x200
  [ 2339.008581]  [<ffffffff8121f8b3>] do_execveat_common.isra.33+0x543/0x6e0
  [ 2339.016072]  [<ffffffff8121fcea>] SyS_execve+0x3a/0x50
  [ 2339.021819]  [<ffffffff819fc165>] stub_execve+0x5/0x5
  [ 2339.027469]  [<ffffffff819fbeb2>] ? entry_SYSCALL_64_fastpath+0x12/0x71
  [ 2339.034860] ---[ end trace ee1337c59a0ddeac ]---

Which is a WARN_ON_ONCE() indicating that cpuctx->task_ctx is not
what we expected it to be.

This is because context switches can swap the task_struct::perf_event_ctxp[]
pointer around. Therefore you have to either disable preemption when looking
at current, or hold ctx->lock.

Fix perf_event_enable_on_exec(), it loads current->perf_event_ctxp[]
before disabling interrupts, therefore a preemption in the right place
can swap contexts around and we're using the wrong one.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: syzkaller <syzkaller@googlegroups.com>
Link: http://lkml.kernel.org/r/20151210195740.GG6357@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-06 10:52:38 +01:00
Linus Torvalds
ee9a7d2cb0 Two more fixes.
1. The recordmcount change had an output that used sprintf() (incorrectly)
     when it should have been a fprintf() to stderr.
 
  2. The printk_formats file could crash if someone added a trace_printk()
     in the core kernel, and also added one in a module. This does not
     affect production kernels. Only kernels where developers add trace_printk()
     for debugging can crash.
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Merge tag 'trace-v4.4-rc4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "Two more fixes:

  1. The recordmcount change had an output that used sprintf()
     (incorrectly) when it should have been a fprintf() to stderr.

  2. The printk_formats file could crash if someone added a
     trace_printk() in the core kernel, and also added one in a module.
     This does not affect production kernels.  Only kernels where
     developers add trace_printk() for debugging can crash"

* tag 'trace-v4.4-rc4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Fix setting of start_index in find_next()
  ftrace/scripts: Fix incorrect use of sprintf in recordmcount
2016-01-05 13:32:39 -08:00
Qiu Peiyang
f36d1be293 tracing: Fix setting of start_index in find_next()
When we do cat /sys/kernel/debug/tracing/printk_formats, we hit kernel
panic at t_show.

general protection fault: 0000 [#1] PREEMPT SMP
CPU: 0 PID: 2957 Comm: sh Tainted: G W  O 3.14.55-x86_64-01062-gd4acdc7 #2
RIP: 0010:[<ffffffff811375b2>]
 [<ffffffff811375b2>] t_show+0x22/0xe0
RSP: 0000:ffff88002b4ebe80  EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000004
RDX: 0000000000000004 RSI: ffffffff81fd26a6 RDI: ffff880032f9f7b1
RBP: ffff88002b4ebe98 R08: 0000000000001000 R09: 000000000000ffec
R10: 0000000000000000 R11: 000000000000000f R12: ffff880004d9b6c0
R13: 7365725f6d706400 R14: ffff880004d9b6c0 R15: ffffffff82020570
FS:  0000000000000000(0000) GS:ffff88003aa00000(0063) knlGS:00000000f776bc40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f6c02ff0 CR3: 000000002c2b3000 CR4: 00000000001007f0
Call Trace:
 [<ffffffff811dc076>] seq_read+0x2f6/0x3e0
 [<ffffffff811b749b>] vfs_read+0x9b/0x160
 [<ffffffff811b7f69>] SyS_read+0x49/0xb0
 [<ffffffff81a3a4b9>] ia32_do_call+0x13/0x13
 ---[ end trace 5bd9eb630614861e ]---
Kernel panic - not syncing: Fatal exception

When the first time find_next calls find_next_mod_format, it should
iterate the trace_bprintk_fmt_list to find the first print format of
the module. However in current code, start_index is smaller than *pos
at first, and code will not iterate the list. Latter container_of will
get the wrong address with former v, which will cause mod_fmt be a
meaningless object and so is the returned mod_fmt->fmt.

This patch will fix it by correcting the start_index. After fixed,
when the first time calls find_next_mod_format, start_index will be
equal to *pos, and code will iterate the trace_bprintk_fmt_list to
get the right module printk format, so is the returned mod_fmt->fmt.

Link: http://lkml.kernel.org/r/5684B900.9000309@intel.com

Cc: stable@vger.kernel.org # 3.12+
Fixes: 102c9323c3 "tracing: Add __tracepoint_string() to export string pointers"
Signed-off-by: Qiu Peiyang <peiyangx.qiu@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2016-01-04 15:22:47 -05:00
Will Deacon
b4b29f9485 locking/osq: Fix ordering of node initialisation in osq_lock
The Cavium guys reported a soft lockup on their arm64 machine, caused by
commit c55a6ffa62 ("locking/osq: Relax atomic semantics"):

    mutex_optimistic_spin+0x9c/0x1d0
    __mutex_lock_slowpath+0x44/0x158
    mutex_lock+0x54/0x58
    kernfs_iop_permission+0x38/0x70
    __inode_permission+0x88/0xd8
    inode_permission+0x30/0x6c
    link_path_walk+0x68/0x4d4
    path_openat+0xb4/0x2bc
    do_filp_open+0x74/0xd0
    do_sys_open+0x14c/0x228
    SyS_openat+0x3c/0x48
    el0_svc_naked+0x24/0x28

This is because in osq_lock we initialise the node for the current CPU:

    node->locked = 0;
    node->next = NULL;
    node->cpu = curr;

and then publish the current CPU in the lock tail:

    old = atomic_xchg_acquire(&lock->tail, curr);

Once the update to lock->tail is visible to another CPU, the node is
then live and can be both read and updated by concurrent lockers.

Unfortunately, the ACQUIRE semantics of the xchg operation mean that
there is no guarantee the contents of the node will be visible before
lock tail is updated.  This can lead to lock corruption when, for
example, a concurrent locker races to set the next field.

Fixes: c55a6ffa62 ("locking/osq: Relax atomic semantics"):
Reported-by: David Daney <ddaney@caviumnetworks.com>
Reported-by: Andrew Pinski <andrew.pinski@caviumnetworks.com>
Tested-by: Andrew Pinski <andrew.pinski@caviumnetworks.com>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1449856001-21177-1-git-send-email-will.deacon@arm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-12-17 11:40:29 -08:00
Thomas Gleixner
abc7e40c81 genirq: Prevent chip buslock deadlock
If a interrupt chip utilizes chip->buslock then free_irq() can
deadlock in the following way:

CPU0				CPU1
				interrupt(X) (Shared or spurious)
free_irq(X)			interrupt_thread(X)
chip_bus_lock(X)
				   irq_finalize_oneshot(X)
				     chip_bus_lock(X)
synchronize_irq(X)
	
synchronize_irq() waits for the interrupt thread to complete,
i.e. forever.

Solution is simple: Drop chip_bus_lock() before calling
synchronize_irq() as we do with the irq_desc lock. There is nothing to
be protected after the point where irq_desc lock has been released.

This adds chip_bus_lock/unlock() to the remove_irq() code path, but
that's actually correct in the case where remove_irq() is called on
such an interrupt. The current users of remove_irq() are not affected
as none of those interrupts is on a chip which requires buslock.

Reported-by: Fredrik Markström <fredrik.markstrom@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
2015-12-14 09:45:06 +01:00
Peter Zijlstra
dfd01f0260 sched/wait: Fix the signal handling fix
Jan Stancek reported that I wrecked things for him by fixing things for
Vladimir :/

His report was due to an UNINTERRUPTIBLE wait getting -EINTR, which
should not be possible, however my previous patch made this possible by
unconditionally checking signal_pending().

We cannot use current->state as was done previously, because the
instruction after the store to that variable it can be changed.  We must
instead pass the initial state along and use that.

Fixes: 68985633bc ("sched/wait: Fix signal handling in bit wait helpers")
Reported-by: Jan Stancek <jstancek@redhat.com>
Reported-by: Chris Mason <clm@fb.com>
Tested-by: Jan Stancek <jstancek@redhat.com>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com>
Tested-by: Chris Mason <clm@fb.com>
Reviewed-by: Paul Turner <pjt@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: tglx@linutronix.de
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: hpa@zytor.com
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-12-13 14:30:59 -08:00
Chris Wilson
86fffe4a61 kernel: remove stop_machine() Kconfig dependency
Currently the full stop_machine() routine is only enabled on SMP if
module unloading is enabled, or if the CPUs are hotpluggable.  This
leads to configurations where stop_machine() is broken as it will then
only run the callback on the local CPU with irqs disabled, and not stop
the other CPUs or run the callback on them.

For example, this breaks MTRR setup on x86 in certain configs since
ea8596bb2d ("kprobes/x86: Remove unused text_poke_smp() and
text_poke_smp_batch() functions") as the MTRR is only established on the
boot CPU.

This patch removes the Kconfig option for STOP_MACHINE and uses the SMP
and HOTPLUG_CPU config options to compile the correct stop_machine() for
the architecture, removing the false dependency on MODULE_UNLOAD in the
process.

Link: https://lkml.org/lkml/2014/10/8/124
References: https://bugs.freedesktop.org/show_bug.cgi?id=84794
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Pranith Kumar <bobby.prani@gmail.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Iulia Manda <iulia.manda21@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Chuck Ebbert <cebbert.lkml@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-12-12 10:15:34 -08:00
Linus Torvalds
5406812e59 Merge branch 'for-4.4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
 "More change than I'd have liked at this stage.  The pids controller
  and the changes made to cgroup core to support it introduced and
  revealed several important issues.

   - Assigning membership to a newly created task and migrating it can
     race leading to incorrect accounting.  Oleg fixed it by widening
     threadgroup synchronization.  It looks like we'll be able to merge
     it with a different percpu rwsem which is used in fork path making
     things simpler and cheaper.

   - The recent change to extend cgroup membership to zombies (so that
     pid accounting can extend till the pid is actually released) missed
     pinning the underlying data structures leading to use-after-free.
     Fixed.

   - v2 hierarchy was calling subsystem callbacks with the wrong target
     cgroup_subsys_state based on the incorrect assumption that they
     share the same target.  pids is the first controller affected by
     this.  Subsys callbacks updated so that they can deal with
     multi-target migrations"

* 'for-4.4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup_pids: don't account for the root cgroup
  cgroup: fix handling of multi-destination migration from subtree_control enabling
  cgroup_freezer: simplify propagation of CGROUP_FROZEN clearing in freezer_attach()
  cgroup: pids: kill pids_fork(), simplify pids_can_fork() and pids_cancel_fork()
  cgroup: pids: fix race between cgroup_post_fork() and cgroup_migrate()
  cgroup: make css_set pin its css's to avoid use-afer-free
  cgroup: fix cftype->file_offset handling
2015-12-08 13:35:52 -08:00
Linus Torvalds
51825c8a86 Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Ingo Molnar:
 "This tree includes four core perf fixes for misc bugs, three fixes to
  x86 PMU drivers, and two updates to old email addresses"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf: Do not send exit event twice
  perf/x86/intel: Fix INTEL_FLAGS_UEVENT_CONSTRAINT_DATALA_NA macro
  perf/x86/intel: Make L1D_PEND_MISS.FB_FULL not constrained on Haswell
  perf: Fix PERF_EVENT_IOC_PERIOD deadlock
  treewide: Remove old email address
  perf/x86: Fix LBR call stack save/restore
  perf: Update email address in MAINTAINERS
  perf/core: Robustify the perf_cgroup_from_task() RCU checks
  perf/core: Fix RCU problem with cgroup context switching code
2015-12-08 13:01:23 -08:00
Tejun Heo
0b98f0c042 Merge branch 'master' into for-4.4-fixes
The following commit which went into mainline through networking tree

  3b13758f51 ("cgroups: Allow dynamically changing net_classid")

conflicts in net/core/netclassid_cgroup.c with the following pending
fix in cgroup/for-4.4-fixes.

  1f7dd3e5a6 ("cgroup: fix handling of multi-destination migration from subtree_control enabling")

The former separates out update_classid() from cgrp_attach() and
updates it to walk all fds of all tasks in the target css so that it
can be used from both migration and config change paths.  The latter
drops @css from cgrp_attach().

Resolve the conflict by making cgrp_attach() call update_classid()
with the css from the first task.  We can revive @tset walking in
cgrp_attach() but given that net_cls is v1 only where there always is
only one target css during migration, this is fine.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Nina Schiff <ninasc@fb.com>
2015-12-07 10:09:03 -05:00
Linus Torvalds
fb7b26e47e Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Thomas Gleixner:
 "This updates contains the following changes:

   - Fix a signal handling regression in the bit wait functions.

   - Avoid false positive warnings in the wakeup path.

   - Initialize the scheduler root domain properly.

   - Handle gtime calculations in proc/$PID/stat proper.

   - Add more documentation for the barriers in try_to_wake_up().

   - Fix a subtle race in try_to_wake_up() which might cause a task to
     be scheduled on two cpus

   - Compile static helper function only when it is used"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/core: Fix an SMP ordering race in try_to_wake_up() vs. schedule()
  sched/core: Better document the try_to_wake_up() barriers
  sched/cputime: Fix invalid gtime in proc
  sched/core: Clear the root_domain cpumasks in init_rootdomain()
  sched/core: Remove false-positive warning from wake_up_process()
  sched/wait: Fix signal handling in bit wait helpers
  sched/rt: Hide the push_irq_work_func() declaration
2015-12-06 08:35:05 -08:00
Jiri Olsa
4e93ad601a perf: Do not send exit event twice
In case we monitor events system wide, we get EXIT event
(when configured) twice for each task that exited.

Note doubled lines with same pid/tid in following example:

  $ sudo ./perf record -a
  ^C[ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.480 MB perf.data (2518 samples) ]
  $ sudo ./perf report -D | grep EXIT

  0 60290687567581 0x59910 [0x38]: PERF_RECORD_EXIT(1250:1250):(1250:1250)
  0 60290687568354 0x59948 [0x38]: PERF_RECORD_EXIT(1250:1250):(1250:1250)
  0 60290687988744 0x59ad8 [0x38]: PERF_RECORD_EXIT(1250:1250):(1250:1250)
  0 60290687989198 0x59b10 [0x38]: PERF_RECORD_EXIT(1250:1250):(1250:1250)
  1 60290692567895 0x62af0 [0x38]: PERF_RECORD_EXIT(1253:1253):(1253:1253)
  1 60290692568322 0x62b28 [0x38]: PERF_RECORD_EXIT(1253:1253):(1253:1253)
  2 60290692739276 0x69a18 [0x38]: PERF_RECORD_EXIT(1252:1252):(1252:1252)
  2 60290692739910 0x69a50 [0x38]: PERF_RECORD_EXIT(1252:1252):(1252:1252)

The reason is that the cpu contexts are processes each time
we call perf_event_task. I'm changing the perf_event_aux logic
to serve task_ctx and cpu contexts separately, which ensure we
don't get EXIT event generated twice on same cpu context.

This does not affect other auxiliary events, as they don't
use task_ctx at all.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/1446649205-5822-1-git-send-email-jolsa@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-06 12:54:49 +01:00
Peter Zijlstra
ecf7d01c22 sched/core: Fix an SMP ordering race in try_to_wake_up() vs. schedule()
Oleg noticed that its possible to falsely observe p->on_cpu == 0 such
that we'll prematurely continue with the wakeup and effectively run p on
two CPUs at the same time.

Even though the overlap is very limited; the task is in the middle of
being scheduled out; it could still result in corruption of the
scheduler data structures.

        CPU0                            CPU1

        set_current_state(...)

        <preempt_schedule>
          context_switch(X, Y)
            prepare_lock_switch(Y)
              Y->on_cpu = 1;
            finish_lock_switch(X)
              store_release(X->on_cpu, 0);

                                        try_to_wake_up(X)
                                          LOCK(p->pi_lock);

                                          t = X->on_cpu; // 0

          context_switch(Y, X)
            prepare_lock_switch(X)
              X->on_cpu = 1;
            finish_lock_switch(Y)
              store_release(Y->on_cpu, 0);
        </preempt_schedule>

        schedule();
          deactivate_task(X);
          X->on_rq = 0;

                                          if (X->on_rq) // false

                                          if (t) while (X->on_cpu)
                                            cpu_relax();

          context_switch(X, ..)
            finish_lock_switch(X)
              store_release(X->on_cpu, 0);

Avoid the load of X->on_cpu being hoisted over the X->on_rq load.

Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04 10:26:43 +01:00
Peter Zijlstra
b75a225315 sched/core: Better document the try_to_wake_up() barriers
Explain how the control dependency and smp_rmb() end up providing
ACQUIRE semantics and pair with smp_store_release() in
finish_lock_switch().

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04 10:26:42 +01:00
Hiroshi Shimamoto
2541117b0c sched/cputime: Fix invalid gtime in proc
/proc/stats shows invalid gtime when the thread is running in guest.
When vtime accounting is not enabled, we cannot get a valid delta.
The delta is calculated with now - tsk->vtime_snap, but tsk->vtime_snap
is only updated when vtime accounting is runtime enabled.

This patch makes task_gtime() just return gtime without computing the
buggy non-existing tickless delta when vtime accounting is not enabled.

Use context_tracking_is_enabled() to check if vtime is accounting on
some cpu, in which case only we need to check the tickless delta. This
way we fix the gtime value regression on machines not running nohz full.

The kernel config contains CONFIG_VIRT_CPU_ACCOUNTING_GEN=y and
CONFIG_NO_HZ_FULL_ALL=n and boot without nohz_full.

I ran and stop a busy loop in VM and see the gtime in host.
Dump the 43rd field which shows the gtime in every second:

	 # while :; do awk '{print $3" "$43}' /proc/3955/task/4014/stat; sleep 1; done
	S 4348
	R 7064566
	R 7064766
	R 7064967
	R 7065168
	S 4759
	S 4759

During running busy loop, it returns large value.

After applying this patch, we can see right gtime.

	 # while :; do awk '{print $3" "$43}' /proc/10913/task/10956/stat; sleep 1; done
	S 5338
	R 5365
	R 5465
	R 5566
	R 5666
	S 5726
	S 5726

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1447948054-28668-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04 10:18:49 +01:00
Xunlei Pang
8295c69925 sched/core: Clear the root_domain cpumasks in init_rootdomain()
root_domain::rto_mask allocated through alloc_cpumask_var()
contains garbage data, this may cause problems. For instance,
When doing pull_rt_task(), it may do useless iterations if
rto_mask retains some extra garbage bits. Worse still, this
violates the isolated domain rule for clustered scheduling
using cpuset, because the tasks(with all the cpus allowed)
belongs to one root domain can be pulled away into another
root domain.

The patch cleans the garbage by using zalloc_cpumask_var()
instead of alloc_cpumask_var() for root_domain::rto_mask
allocation, thereby addressing the issues.

Do the same thing for root_domain's other cpumask memembers:
dlo_mask, span, and online.

Signed-off-by: Xunlei Pang <xlpang@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1449057179-29321-1-git-send-email-xlpang@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04 10:16:21 +01:00
Sasha Levin
119d6f6a3b sched/core: Remove false-positive warning from wake_up_process()
Because wakeups can (fundamentally) be late, a task might not be in
the expected state. Therefore testing against a task's state is racy,
and can yield false positives.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: oleg@redhat.com
Fixes: 9067ac85d5 ("wake_up_process() should be never used to wakeup a TASK_STOPPED/TRACED task")
Link: http://lkml.kernel.org/r/1448933660-23082-1-git-send-email-sasha.levin@oracle.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04 10:10:16 +01:00
Peter Zijlstra
68985633bc sched/wait: Fix signal handling in bit wait helpers
Vladimir reported getting RCU stall warnings and bisected it back to
commit:

  743162013d ("sched: Remove proliferation of wait_on_bit() action functions")

That commit inadvertently reversed the calls to schedule() and signal_pending(),
thereby not handling the case where the signal receives while we sleep.

Reported-by: Vladimir Murzin <vladimir.murzin@arm.com>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: mark.rutland@arm.com
Cc: neilb@suse.de
Cc: oleg@redhat.com
Fixes: 743162013d ("sched: Remove proliferation of wait_on_bit() action functions")
Fixes: cbbce82209 ("SCHED: add some "wait..on_bit...timeout()" interfaces.")
Link: http://lkml.kernel.org/r/20151201130404.GL3816@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04 10:10:15 +01:00
Peter Zijlstra
642c2d671c perf: Fix PERF_EVENT_IOC_PERIOD deadlock
Dmitry reported a fairly silly recursive lock deadlock for
PERF_EVENT_IOC_PERIOD, fix this by explicitly doing the inactive part of
__perf_event_period() instead of calling that function.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Fixes: c7999c6f3f ("perf: Fix PERF_EVENT_IOC_PERIOD migration race")
Link: http://lkml.kernel.org/r/20151130115615.GJ17308@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-12-04 10:08:03 +01:00
Linus Torvalds
071f5d105a Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Pull networking fixes from David Miller:
 "A lot of Thanksgiving turkey leftovers accumulated, here goes:

   1) Fix bluetooth l2cap_chan object leak, from Johan Hedberg.

   2) IDs for some new iwlwifi chips, from Oren Givon.

   3) Fix rtlwifi lockups on boot, from Larry Finger.

   4) Fix memory leak in fm10k, from Stephen Hemminger.

   5) We have a route leak in the ipv6 tunnel infrastructure, fix from
      Paolo Abeni.

   6) Fix buffer pointer handling in arm64 bpf JIT,f rom Zi Shen Lim.

   7) Wrong lockdep annotations in tcp md5 support, fix from Eric
      Dumazet.

   8) Work around some middle boxes which prevent proper handling of TCP
      Fast Open, from Yuchung Cheng.

   9) TCP repair can do huge kmalloc() requests, build paged SKBs
      instead.  From Eric Dumazet.

  10) Fix msg_controllen overflow in scm_detach_fds, from Daniel
      Borkmann.

  11) Fix device leaks on ipmr table destruction in ipv4 and ipv6, from
      Nikolay Aleksandrov.

  12) Fix use after free in epoll with AF_UNIX sockets, from Rainer
      Weikusat.

  13) Fix double free in VRF code, from Nikolay Aleksandrov.

  14) Fix skb leaks on socket receive queue in tipc, from Ying Xue.

  15) Fix ifup/ifdown crach in xgene driver, from Iyappan Subramanian.

  16) Fix clearing of persistent array maps in bpf, from Daniel
      Borkmann.

  17) In TCP, for the cross-SYN case, we don't initialize tp->copied_seq
      early enough.  From Eric Dumazet.

  18) Fix out of bounds accesses in bpf array implementation when
      updating elements, from Daniel Borkmann.

  19) Fill gaps in RCU protection of np->opt in ipv6 stack, from Eric
      Dumazet.

  20) When dumping proxy neigh entries, we have to accomodate NULL
      device pointers properly, from Konstantin Khlebnikov.

  21) SCTP doesn't release all ipv6 socket resources properly, fix from
      Eric Dumazet.

  22) Prevent underflows of sch->q.qlen for multiqueue packet
      schedulers, also from Eric Dumazet.

  23) Fix MAC and unicast list handling in bnxt_en driver, from Jeffrey
      Huang and Michael Chan.

  24) Don't actively scan radar channels, from Antonio Quartulli"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (110 commits)
  net: phy: reset only targeted phy
  bnxt_en: Setup uc_list mac filters after resetting the chip.
  bnxt_en: enforce proper storing of MAC address
  bnxt_en: Fixed incorrect implementation of ndo_set_mac_address
  net: lpc_eth: remove irq > NR_IRQS check from probe()
  net_sched: fix qdisc_tree_decrease_qlen() races
  openvswitch: fix hangup on vxlan/gre/geneve device deletion
  ipv4: igmp: Allow removing groups from a removed interface
  ipv6: sctp: implement sctp_v6_destroy_sock()
  arm64: bpf: add 'store immediate' instruction
  ipv6: kill sk_dst_lock
  ipv6: sctp: add rcu protection around np->opt
  net/neighbour: fix crash at dumping device-agnostic proxy entries
  sctp: use GFP_USER for user-controlled kmalloc
  sctp: convert sack_needed and sack_generation to bits
  ipv6: add complete rcu protection around np->opt
  bpf: fix allocation warnings in bpf maps and integer overflow
  mvebu: dts: enable IP checksum with jumbo frames for Armada 38x on Port0
  net: mvneta: enable setting custom TX IP checksum limit
  net: mvneta: fix error path for building skb
  ...
2015-12-03 16:02:46 -08:00
Linus Torvalds
c041f08738 During the merge window I added a new file that is used to filter trace
events on pids. It filters all events where only tasks with their pid in that
 file exists. It also handles the sched_switch and sched_wakeup trace events
 where the current task does not have its pid in the file, but the task
 either being switched to or awaken does.
 
 Unfortunately, I forgot about sched_wakeup_new and sched_waking. Both of
 these tracepoints use the same class as the sched_wakeup tracepoint, and
 they too should be included in what gets filtered by the set_event_pid file.
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Merge tag 'trace-v4.4-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fix from Steven Rostedt:
 "During the merge window I added a new file that is used to filter
  trace events on pids.  It filters all events where only tasks with
  their pid in that file exists.  It also handles the sched_switch and
  sched_wakeup trace events where the current task does not have its pid
  in the file, but the task either being switched to or awaken does.

  Unfortunately, I forgot about sched_wakeup_new and sched_waking.  Both
  of these tracepoints use the same class as the sched_wakeup
  tracepoint, and they too should be included in what gets filtered by
  the set_event_pid file"

* tag 'trace-v4.4-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Add sched_wakeup_new and sched_waking tracepoints for pid filter
2015-12-03 15:23:17 -08:00
Tejun Heo
67cde9c493 cgroup_pids: don't account for the root cgroup
Because accounting resources for the root cgroup sometimes incurs
measureable overhead for workloads which don't care about cgroup and
often ends up calculating a number which is available elsewhere in a
slightly different form, cgroup is not in the business of providing
system-wide statistics.  The pids controller which was introduced
recently was exposing "pids.current" at the root.  This patch disable
accounting for root cgroup and removes the file from the root
directory.

While this is a userland visible behavior change, pids has been
available only in one version and was badly broken there, so I don't
think this will be noticeable.  If it turns out to be a problem, we
can reinstate it for v1 hierarchies.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Aleksa Sarai <cyphar@cyphar.com>
2015-12-03 10:18:21 -05:00
Tejun Heo
1f7dd3e5a6 cgroup: fix handling of multi-destination migration from subtree_control enabling
Consider the following v2 hierarchy.

  P0 (+memory) --- P1 (-memory) --- A
                                 \- B
       
P0 has memory enabled in its subtree_control while P1 doesn't.  If
both A and B contain processes, they would belong to the memory css of
P1.  Now if memory is enabled on P1's subtree_control, memory csses
should be created on both A and B and A's processes should be moved to
the former and B's processes the latter.  IOW, enabling controllers
can cause atomic migrations into different csses.

The core cgroup migration logic has been updated accordingly but the
controller migration methods haven't and still assume that all tasks
migrate to a single target css; furthermore, the methods were fed the
css in which subtree_control was updated which is the parent of the
target csses.  pids controller depends on the migration methods to
move charges and this made the controller attribute charges to the
wrong csses often triggering the following warning by driving a
counter negative.

 WARNING: CPU: 1 PID: 1 at kernel/cgroup_pids.c:97 pids_cancel.constprop.6+0x31/0x40()
 Modules linked in:
 CPU: 1 PID: 1 Comm: systemd Not tainted 4.4.0-rc1+ #29
 ...
  ffffffff81f65382 ffff88007c043b90 ffffffff81551ffc 0000000000000000
  ffff88007c043bc8 ffffffff810de202 ffff88007a752000 ffff88007a29ab00
  ffff88007c043c80 ffff88007a1d8400 0000000000000001 ffff88007c043bd8
 Call Trace:
  [<ffffffff81551ffc>] dump_stack+0x4e/0x82
  [<ffffffff810de202>] warn_slowpath_common+0x82/0xc0
  [<ffffffff810de2fa>] warn_slowpath_null+0x1a/0x20
  [<ffffffff8118e031>] pids_cancel.constprop.6+0x31/0x40
  [<ffffffff8118e0fd>] pids_can_attach+0x6d/0xf0
  [<ffffffff81188a4c>] cgroup_taskset_migrate+0x6c/0x330
  [<ffffffff81188e05>] cgroup_migrate+0xf5/0x190
  [<ffffffff81189016>] cgroup_attach_task+0x176/0x200
  [<ffffffff8118949d>] __cgroup_procs_write+0x2ad/0x460
  [<ffffffff81189684>] cgroup_procs_write+0x14/0x20
  [<ffffffff811854e5>] cgroup_file_write+0x35/0x1c0
  [<ffffffff812e26f1>] kernfs_fop_write+0x141/0x190
  [<ffffffff81265f88>] __vfs_write+0x28/0xe0
  [<ffffffff812666fc>] vfs_write+0xac/0x1a0
  [<ffffffff81267019>] SyS_write+0x49/0xb0
  [<ffffffff81bcef32>] entry_SYSCALL_64_fastpath+0x12/0x76

This patch fixes the bug by removing @css parameter from the three
migration methods, ->can_attach, ->cancel_attach() and ->attach() and
updating cgroup_taskset iteration helpers also return the destination
css in addition to the task being migrated.  All controllers are
updated accordingly.

* Controllers which don't care whether there are one or multiple
  target csses can be converted trivially.  cpu, io, freezer, perf,
  netclassid and netprio fall in this category.

* cpuset's current implementation assumes that there's single source
  and destination and thus doesn't support v2 hierarchy already.  The
  only change made by this patchset is how that single destination css
  is obtained.

* memory migration path already doesn't do anything on v2.  How the
  single destination css is obtained is updated and the prep stage of
  mem_cgroup_can_attach() is reordered to accomodate the change.

* pids is the only controller which was affected by this bug.  It now
  correctly handles multi-destination migrations and no longer causes
  counter underflow from incorrect accounting.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Aleksa Sarai <cyphar@cyphar.com>
2015-12-03 10:18:21 -05:00
Tejun Heo
599c963a0f cgroup_freezer: simplify propagation of CGROUP_FROZEN clearing in freezer_attach()
If one or more tasks get moved into a frozen css, the frozen state is
cleared up from the destination css so that it can be reasserted once
the migrated tasks are frozen.  freezer_attach() implements this in
two separate steps - clearing CGROUP_FROZEN on the target css while
processing each task and propagating the clearing upwards after the
task loop is done if necessary.

This patch merges the two steps.  Propagation now takes place inside
the task loop.  This simplifies the code and prepares it for the fix
of multi-destination migration.

Signed-off-by: Tejun Heo <tj@kernel.org>
2015-12-03 10:18:21 -05:00
Alexei Starovoitov
01b3f52157 bpf: fix allocation warnings in bpf maps and integer overflow
For large map->value_size the user space can trigger memory allocation warnings like:
WARNING: CPU: 2 PID: 11122 at mm/page_alloc.c:2989
__alloc_pages_nodemask+0x695/0x14e0()
Call Trace:
 [<     inline     >] __dump_stack lib/dump_stack.c:15
 [<ffffffff82743b56>] dump_stack+0x68/0x92 lib/dump_stack.c:50
 [<ffffffff81244ec9>] warn_slowpath_common+0xd9/0x140 kernel/panic.c:460
 [<ffffffff812450f9>] warn_slowpath_null+0x29/0x30 kernel/panic.c:493
 [<     inline     >] __alloc_pages_slowpath mm/page_alloc.c:2989
 [<ffffffff81554e95>] __alloc_pages_nodemask+0x695/0x14e0 mm/page_alloc.c:3235
 [<ffffffff816188fe>] alloc_pages_current+0xee/0x340 mm/mempolicy.c:2055
 [<     inline     >] alloc_pages include/linux/gfp.h:451
 [<ffffffff81550706>] alloc_kmem_pages+0x16/0xf0 mm/page_alloc.c:3414
 [<ffffffff815a1c89>] kmalloc_order+0x19/0x60 mm/slab_common.c:1007
 [<ffffffff815a1cef>] kmalloc_order_trace+0x1f/0xa0 mm/slab_common.c:1018
 [<     inline     >] kmalloc_large include/linux/slab.h:390
 [<ffffffff81627784>] __kmalloc+0x234/0x250 mm/slub.c:3525
 [<     inline     >] kmalloc include/linux/slab.h:463
 [<     inline     >] map_update_elem kernel/bpf/syscall.c:288
 [<     inline     >] SYSC_bpf kernel/bpf/syscall.c:744

To avoid never succeeding kmalloc with order >= MAX_ORDER check that
elem->value_size and computed elem_size are within limits for both hash and
array type maps.
Also add __GFP_NOWARN to kmalloc(value_size | elem_size) to avoid OOM warnings.
Note kmalloc(key_size) is highly unlikely to trigger OOM, since key_size <= 512,
so keep those kmalloc-s as-is.

Large value_size can cause integer overflows in elem_size and map.pages
formulas, so check for that as well.

Fixes: aaac3ba95e ("bpf: charge user for creation of BPF maps and programs")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-02 23:36:00 -05:00
Daniel Borkmann
fbca9d2d35 bpf, array: fix heap out-of-bounds access when updating elements
During own review but also reported by Dmitry's syzkaller [1] it has been
noticed that we trigger a heap out-of-bounds access on eBPF array maps
when updating elements. This happens with each map whose map->value_size
(specified during map creation time) is not multiple of 8 bytes.

In array_map_alloc(), elem_size is round_up(attr->value_size, 8) and
used to align array map slots for faster access. However, in function
array_map_update_elem(), we update the element as ...

memcpy(array->value + array->elem_size * index, value, array->elem_size);

... where we access 'value' out-of-bounds, since it was allocated from
map_update_elem() from syscall side as kmalloc(map->value_size, GFP_USER)
and later on copied through copy_from_user(value, uvalue, map->value_size).
Thus, up to 7 bytes, we can access out-of-bounds.

Same could happen from within an eBPF program, where in worst case we
access beyond an eBPF program's designated stack.

Since 1be7f75d16 ("bpf: enable non-root eBPF programs") didn't hit an
official release yet, it only affects priviledged users.

In case of array_map_lookup_elem(), the verifier prevents eBPF programs
from accessing beyond map->value_size through check_map_access(). Also
from syscall side map_lookup_elem() only copies map->value_size back to
user, so nothing could leak.

  [1] http://github.com/google/syzkaller

Fixes: 28fbcfa08d ("bpf: add array type of eBPF maps")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-01 21:56:17 -05:00
Steven Rostedt (Red Hat)
0f72e37e42 tracing: Add sched_wakeup_new and sched_waking tracepoints for pid filter
The set_event_pid filter relies on attaching to the sched_switch and
sched_wakeup tracepoints to see if it should filter the tracing on schedule
tracepoints. By adding the callbacks to sched_wakeup, pids in the
set_event_pid file will trace the wakeups of those tasks with those pids.

But sched_wakeup_new and sched_waking were missed. These two should also be
traced. Luckily, these tracepoints share the same class as sched_wakeup
which means they can use the same pre and post callbacks as sched_wakeup
does.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2015-12-01 16:08:05 -05:00
Linus Torvalds
9e5d25e829 Found two minor bugs while doing development on the ring buffer code.
The first is something that's been there since its creation. If a reader
 reads a page out of the ring buffer before there's any events on it, it
 can get an out of date timestamp for that event. It may be off by a few
 microseconds, more if the first event gets discarded. The fix was to
 only update the reader time stamp when it actually sees an event on
 the page, instead of just reading the timestamp from the page even if
 it has no events on it. That timestamp is still volatile until an event
 is present.
 
 The second bug is more recent. Instead of passing around parameters
 a descriptor was made and the parameters are passed via a single
 descriptor. This simplified the code a bit. But there was one place that
 expected the parameter to be passed by value not reference (which a
 descriptor now does). And it added to the length of the event, which
 may be ignored later, but the length should not have been increased.
 The only real problem with this bug is that it may allocate more than
 was needed for the event.
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Merge tag 'trace-v4.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "I found two minor bugs while doing development on the ring buffer
  code.

  The first is something that's been there since its creation.  If a
  reader reads a page out of the ring buffer before there's any events
  on it, it can get an out of date timestamp for that event.  It may be
  off by a few microseconds, more if the first event gets discarded.
  The fix was to only update the reader time stamp when it actually sees
  an event on the page, instead of just reading the timestamp from the
  page even if it has no events on it.  That timestamp is still volatile
  until an event is present.

  The second bug is more recent.  Instead of passing around parameters a
  descriptor was made and the parameters are passed via a single
  descriptor.  This simplified the code a bit.  But there was one place
  that expected the parameter to be passed by value not reference (which
  a descriptor now does).  And it added to the length of the event,
  which may be ignored later, but the length should not have been
  increased.  The only real problem with this bug is that it may
  allocate more than was needed for the event"

* tag 'trace-v4.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ring-buffer: Put back the length if crossed page with add_timestamp
  ring-buffer: Update read stamp with first real commit on page
2015-11-30 15:38:23 -08:00
Oleg Nesterov
afbcb364be cgroup: pids: kill pids_fork(), simplify pids_can_fork() and pids_cancel_fork()
Now that we know that the forking task can't migrate amd the child is always
moved to the same cgroup by cgroup_post_fork()->css_set_move_task() we can
change pids_can_fork() and pids_cancel_fork() to just use task_css(current).
And since we no longer need to pin this css, we can remove pid_fork().

Note: the patch uses task_css_check(true), perhaps it makes sense to add a
helper or change task_css_set_check() to take cgroup_threadgroup_rwsem into
account.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2015-11-30 09:48:18 -05:00
Oleg Nesterov
c9e75f0492 cgroup: pids: fix race between cgroup_post_fork() and cgroup_migrate()
If the new child migrates to another cgroup before cgroup_post_fork() calls
subsys->fork(), then both pids_can_attach() and pids_fork() will do the same
pids_uncharge(old_pids) + pids_charge(pids) sequence twice.

Change copy_process() to call threadgroup_change_begin/threadgroup_change_end
unconditionally. percpu_down_read() is cheap and this allows other cleanups,
see the next changes.

Also, this way we can unify cgroup_threadgroup_rwsem and dup_mmap_sem.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2015-11-30 09:48:18 -05:00
Tejun Heo
53254f900b cgroup: make css_set pin its css's to avoid use-afer-free
A css_set represents the relationship between a set of tasks and
css's.  css_set never pinned the associated css's.  This was okay
because tasks used to always disassociate immediately (in RCU sense) -
either a task is moved to a different css_set or exits and never
accesses css_set again.

Unfortunately, afcf6c8b75 ("cgroup: add cgroup_subsys->free() method
and use it to fix pids controller") and patches leading up to it made
a zombie hold onto its css_set and deref the associated css's on its
release.  Nothing pins the css's after exit and it might have already
been freed leading to use-after-free.

 general protection fault: 0000 [#1] PREEMPT SMP
 task: ffffffff81bf2500 ti: ffffffff81be4000 task.ti: ffffffff81be4000
 RIP: 0010:[<ffffffff810fa205>]  [<ffffffff810fa205>] pids_cancel.constprop.4+0x5/0x40
 ...
 Call Trace:
  <IRQ>
  [<ffffffff810fb02d>] ? pids_free+0x3d/0xa0
  [<ffffffff810f8893>] cgroup_free+0x53/0xe0
  [<ffffffff8104ed62>] __put_task_struct+0x42/0x130
  [<ffffffff81053557>] delayed_put_task_struct+0x77/0x130
  [<ffffffff810c6b34>] rcu_process_callbacks+0x2f4/0x820
  [<ffffffff810c6af3>] ? rcu_process_callbacks+0x2b3/0x820
  [<ffffffff81056e54>] __do_softirq+0xd4/0x460
  [<ffffffff81057369>] irq_exit+0x89/0xa0
  [<ffffffff81876212>] smp_apic_timer_interrupt+0x42/0x50
  [<ffffffff818747f4>] apic_timer_interrupt+0x84/0x90
  <EOI>
 ...
 Code: 5b 5d c3 48 89 df 48 c7 c2 c9 f9 ae 81 48 c7 c6 91 2c ae 81 e8 1d 94 0e 00 31 c0 5b 5d c3 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 <f0> 48 83 87 e0 00 00 00 ff 78 01 c3 80 3d 08 7a c1 00 00 74 02
 RIP  [<ffffffff810fa205>] pids_cancel.constprop.4+0x5/0x40
  RSP <ffff88001fc03e20>
 ---[ end trace 89a4a4b916b90c49 ]---
 Kernel panic - not syncing: Fatal exception in interrupt
 Kernel Offset: disabled
 ---[ end Kernel panic - not syncing: Fatal exception in interrupt

Fix it by making css_set pin the associate css's until its release.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Reported-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Link: http://lkml.kernel.org/g/20151120041836.GA18390@codemonkey.org.uk
Link: http://lkml.kernel.org/g/5652D448.3080002@bmw-carit.de
Fixes: afcf6c8b75 ("cgroup: add cgroup_subsys->free() method and use it to fix pids controller")
2015-11-30 09:46:21 -05:00
Daniel Borkmann
c9da161c65 bpf: fix clearing on persistent program array maps
Currently, when having map file descriptors pointing to program arrays,
there's still the issue that we unconditionally flush program array
contents via bpf_fd_array_map_clear() in bpf_map_release(). This happens
when such a file descriptor is released and is independent of the map's
refcount.

Having this flush independent of the refcount is for a reason: there
can be arbitrary complex dependency chains among tail calls, also circular
ones (direct or indirect, nesting limit determined during runtime), and
we need to make sure that the map drops all references to eBPF programs
it holds, so that the map's refcount can eventually drop to zero and
initiate its freeing. Btw, a walk of the whole dependency graph would
not be possible for various reasons, one being complexity and another
one inconsistency, i.e. new programs can be added to parts of the graph
at any time, so there's no guaranteed consistent state for the time of
such a walk.

Now, the program array pinning itself works, but the issue is that each
derived file descriptor on close would nevertheless call unconditionally
into bpf_fd_array_map_clear(). Instead, keep track of users and postpone
this flush until the last reference to a user is dropped. As this only
concerns a subset of references (f.e. a prog array could hold a program
that itself has reference on the prog array holding it, etc), we need to
track them separately.

Short analysis on the refcounting: on map creation time usercnt will be
one, so there's no change in behaviour for bpf_map_release(), if unpinned.
If we already fail in map_create(), we are immediately freed, and no
file descriptor has been made public yet. In bpf_obj_pin_user(), we need
to probe for a possible map in bpf_fd_probe_obj() already with a usercnt
reference, so before we drop the reference on the fd with fdput().
Therefore, if actual pinning fails, we need to drop that reference again
in bpf_any_put(), otherwise we keep holding it. When last reference
drops on the inode, the bpf_any_put() in bpf_evict_inode() will take
care of dropping the usercnt again. In the bpf_obj_get_user() case, the
bpf_any_get() will grab a reference on the usercnt, still at a time when
we have the reference on the path. Should we later on fail to grab a new
file descriptor, bpf_any_put() will drop it, otherwise we hold it until
bpf_map_release() time.

Joint work with Alexei.

Fixes: b2197755b2 ("bpf: add support for persistent maps/progs")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-11-25 12:14:09 -05:00
Eric Dumazet
81b1a832d7 pidns: fix NULL dereference in __task_pid_nr_ns()
I got a crash during a "perf top" session that was caused by a race in
__task_pid_nr_ns() :

pid_nr_ns() was inlined, but apparently compiler chose to read
task->pids[type].pid twice, and the pid->level dereference crashed
because we got a NULL pointer at the second read :

    if (pid && ns->level <= pid->level) { // CRASH

Just use RCU API properly to solve this race, and not worry about "perf
top" crashing hosts :(

get_task_pid() can benefit from same fix.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-24 12:03:55 -08:00
Steven Rostedt (Red Hat)
bd1b7cd360 ring-buffer: Put back the length if crossed page with add_timestamp
Commit fcc742eaad "ring-buffer: Add event descriptor to simplify passing
data" added a descriptor that holds various data instead of passing around
several variables through parameters. The problem was that one of the
parameters was modified in a function and the code was designed not to have
an effect on that modified  parameter. Now that the parameter is a
descriptor and any modifications to it are non-volatile, the size of the
data could be unnecessarily expanded.

Remove the extra space added if a timestamp was added and the event went
across the page.

Cc: stable@vger.kernel.org # 4.3+
Fixes: fcc742eaad "ring-buffer: Add event descriptor to simplify passing data"
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2015-11-24 09:27:25 -05:00
Steven Rostedt (Red Hat)
b81f472a20 ring-buffer: Update read stamp with first real commit on page
Do not update the read stamp after swapping out the reader page from the
write buffer. If the reader page is swapped out of the buffer before an
event is written to it, then the read_stamp may get an out of date
timestamp, as the page timestamp is updated on the first commit to that
page.

rb_get_reader_page() only returns a page if it has an event on it, otherwise
it will return NULL. At that point, check if the page being returned has
events and has not been read yet. Then at that point update the read_stamp
to match the time stamp of the reader page.

Cc: stable@vger.kernel.org # 2.6.30+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2015-11-24 09:23:17 -05:00
Peter Zijlstra
90eec103b9 treewide: Remove old email address
There were still a number of references to my old Red Hat email
address in the kernel source. Remove these while keeping the
Red Hat copyright notices intact.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-23 09:44:58 +01:00