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  1. 29 9月, 2017 4 次提交
    • E
      sched/sysctl: Check user input value of sysctl_sched_time_avg · 5ccba44b
      由 Ethan Zhao 提交于 
      System will hang if user set sysctl_sched_time_avg to 0:

  [root@XXX ~]# sysctl kernel.sched_time_avg_ms=0

  Stack traceback for pid 0
  0xffff883f6406c600 0 0 1 3 R 0xffff883f6406cf50 *swapper/3
  ffff883f7ccc3ae8 0000000000000018 ffffffff810c4dd0 0000000000000000
  0000000000017800 ffff883f7ccc3d78 0000000000000003 ffff883f7ccc3bf8
  ffffffff810c4fc9 ffff883f7ccc3c08 00000000810c5043 ffff883f7ccc3c08
  Call Trace:
  <IRQ> [<ffffffff810c4dd0>] ? update_group_capacity+0x110/0x200
  [<ffffffff810c4fc9>] ? update_sd_lb_stats+0x109/0x600
  [<ffffffff810c5507>] ? find_busiest_group+0x47/0x530
  [<ffffffff810c5b84>] ? load_balance+0x194/0x900
  [<ffffffff810ad5ca>] ? update_rq_clock.part.83+0x1a/0xe0
  [<ffffffff810c6d42>] ? rebalance_domains+0x152/0x290
  [<ffffffff810c6f5c>] ? run_rebalance_domains+0xdc/0x1d0
  [<ffffffff8108a75b>] ? __do_softirq+0xfb/0x320
  [<ffffffff8108ac85>] ? irq_exit+0x125/0x130
  [<ffffffff810b3a17>] ? scheduler_ipi+0x97/0x160
  [<ffffffff81052709>] ? smp_reschedule_interrupt+0x29/0x30
  [<ffffffff8173a1be>] ? reschedule_interrupt+0x6e/0x80
   <EOI> [<ffffffff815bc83c>] ? cpuidle_enter_state+0xcc/0x230
  [<ffffffff815bc80c>] ? cpuidle_enter_state+0x9c/0x230
  [<ffffffff815bc9d7>] ? cpuidle_enter+0x17/0x20
  [<ffffffff810cd6dc>] ? cpu_startup_entry+0x38c/0x420
  [<ffffffff81053373>] ? start_secondary+0x173/0x1e0

Because divide-by-zero error happens in function:

update_group_capacity()
  update_cpu_capacity()
    scale_rt_capacity()
     {
          ...
          total = sched_avg_period() + delta;
          used = div_u64(avg, total);
          ...
     }

To fix this issue, check user input value of sysctl_sched_time_avg, keep
it unchanged when hitting invalid input, and set the minimum limit of
sysctl_sched_time_avg to 1 ms.
Reported-by: NJames Puthukattukaran <james.puthukattukaran@oracle.com>
Signed-off-by: NEthan Zhao <ethan.zhao@oracle.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: efault@gmx.de
Cc: ethan.kernel@gmail.com
Cc: keescook@chromium.org
Cc: mcgrof@kernel.org
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/1504504774-18253-1-git-send-email-ethan.zhao@oracle.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      5ccba44b
    • P
      sched/debug: Ignore TASK_IDLE for SysRq-W · 5d68cc95
      由 Peter Zijlstra 提交于 
      Markus reported that tasks in TASK_IDLE state are reported by SysRq-W,
which results in undesirable clutter.
Reported-by: NMarkus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      5d68cc95
    • P
      sched/tracing: Use common task-state helpers · 5f6ad26e
      由 Peter Zijlstra 提交于 
      Remove yet another task-state char instance.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      5f6ad26e
    • P
      sched/debug: Remove unused variable · 65d5dc47
      由 Peter Zijlstra 提交于 
      Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      65d5dc47
  3. 28 9月, 2017 1 次提交
  5. 25 9月, 2017 1 次提交
    • W
      blktrace: Fix potential deadlock between delete & sysfs ops · 5acb3cc2
      由 Waiman Long 提交于 
      The lockdep code had reported the following unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(s_active#228);
                               lock(&bdev->bd_mutex/1);
                               lock(s_active#228);
  lock(&bdev->bd_mutex);

 *** DEADLOCK ***

The deadlock may happen when one task (CPU1) is trying to delete a
partition in a block device and another task (CPU0) is accessing
tracing sysfs file (e.g. /sys/block/dm-1/trace/act_mask) in that
partition.

The s_active isn't an actual lock. It is a reference count (kn->count)
on the sysfs (kernfs) file. Removal of a sysfs file, however, require
a wait until all the references are gone. The reference count is
treated like a rwsem using lockdep instrumentation code.

The fact that a thread is in the sysfs callback method or in the
ioctl call means there is a reference to the opended sysfs or device
file. That should prevent the underlying block structure from being
removed.

Instead of using bd_mutex in the block_device structure, a new
blk_trace_mutex is now added to the request_queue structure to protect
access to the blk_trace structure.
Suggested-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NWaiman Long <longman@redhat.com>
Acked-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Fix typo in patch subject line, and prune a comment detailing how
the code used to work.
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      5acb3cc2
  7. 24 9月, 2017 4 次提交
  9. 21 9月, 2017 1 次提交
    • Y
      bpf: one perf event close won't free bpf program attached by another perf event · ec9dd352
      由 Yonghong Song 提交于 
      This patch fixes a bug exhibited by the following scenario:
  1. fd1 = perf_event_open with attr.config = ID1
  2. attach bpf program prog1 to fd1
  3. fd2 = perf_event_open with attr.config = ID1
     <this will be successful>
  4. user program closes fd2 and prog1 is detached from the tracepoint.
  5. user program with fd1 does not work properly as tracepoint
     no output any more.

The issue happens at step 4. Multiple perf_event_open can be called
successfully, but only one bpf prog pointer in the tp_event. In the
current logic, any fd release for the same tp_event will free
the tp_event->prog.

The fix is to free tp_event->prog only when the closing fd
corresponds to the one which registered the program.
Signed-off-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      ec9dd352
  11. 20 9月, 2017 5 次提交
    • D
      bpf: fix ri->map_owner pointer on bpf_prog_realloc · 7c300131
      由 Daniel Borkmann 提交于 
      Commit 109980b8 ("bpf: don't select potentially stale
ri->map from buggy xdp progs") passed the pointer to the prog
itself to be loaded into r4 prior on bpf_redirect_map() helper
call, so that we can store the owner into ri->map_owner out of
the helper.

Issue with that is that the actual address of the prog is still
subject to change when subsequent rewrites occur that require
slow path in bpf_prog_realloc() to alloc more memory, e.g. from
patching inlining helper functions or constant blinding. Thus,
we really need to take prog->aux as the address we're holding,
which also works with prog clones as they share the same aux
object.

Instead of then fetching aux->prog during runtime, which could
potentially incur cache misses due to false sharing, we are
going to just use aux for comparison on the map owner. This
will also keep the patchlet of the same size, and later check
in xdp_map_invalid() only accesses read-only aux pointer from
the prog, it's also in the same cacheline already from prior
access when calling bpf_func.

Fixes: 109980b8 ("bpf: don't select potentially stale ri->map from buggy xdp progs")
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      7c300131
    • E
      bpf: do not disable/enable BH in bpf_map_free_id() · 930651a7
      由 Eric Dumazet 提交于 
      syzkaller reported following splat [1]

Since hard irq are disabled by the caller, bpf_map_free_id()
should not try to enable/disable BH.

Another solution would be to change htab_map_delete_elem() to
defer the free_htab_elem() call after
raw_spin_unlock_irqrestore(&b->lock, flags), but this might be not
enough to cover other code paths.

[1]
WARNING: CPU: 1 PID: 8052 at kernel/softirq.c:161 __local_bh_enable_ip
+0x1e/0x160 kernel/softirq.c:161
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 8052 Comm: syz-executor1 Not tainted 4.13.0-next-20170915+
#23
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:52
 panic+0x1e4/0x417 kernel/panic.c:181
 __warn+0x1c4/0x1d9 kernel/panic.c:542
 report_bug+0x211/0x2d0 lib/bug.c:183
 fixup_bug+0x40/0x90 arch/x86/kernel/traps.c:178
 do_trap_no_signal arch/x86/kernel/traps.c:212 [inline]
 do_trap+0x260/0x390 arch/x86/kernel/traps.c:261
 do_error_trap+0x120/0x390 arch/x86/kernel/traps.c:298
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:311
 invalid_op+0x18/0x20 arch/x86/entry/entry_64.S:905
RIP: 0010:__local_bh_enable_ip+0x1e/0x160 kernel/softirq.c:161
RSP: 0018:ffff8801cdcd7748 EFLAGS: 00010046
RAX: 0000000000000082 RBX: 0000000000000201 RCX: 0000000000000000
RDX: 1ffffffff0b5933c RSI: 0000000000000201 RDI: ffffffff85ac99e0
RBP: ffff8801cdcd7758 R08: ffffffff85b87158 R09: 1ffff10039b9aec6
R10: ffff8801c99f24c0 R11: 0000000000000002 R12: ffffffff817b0b47
R13: dffffc0000000000 R14: ffff8801cdcd77e8 R15: 0000000000000001
 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:176 [inline]
 _raw_spin_unlock_bh+0x30/0x40 kernel/locking/spinlock.c:207
 spin_unlock_bh include/linux/spinlock.h:361 [inline]
 bpf_map_free_id kernel/bpf/syscall.c:197 [inline]
 __bpf_map_put+0x267/0x320 kernel/bpf/syscall.c:227
 bpf_map_put+0x1a/0x20 kernel/bpf/syscall.c:235
 bpf_map_fd_put_ptr+0x15/0x20 kernel/bpf/map_in_map.c:96
 free_htab_elem+0xc3/0x1b0 kernel/bpf/hashtab.c:658
 htab_map_delete_elem+0x74d/0x970 kernel/bpf/hashtab.c:1063
 map_delete_elem kernel/bpf/syscall.c:633 [inline]
 SYSC_bpf kernel/bpf/syscall.c:1479 [inline]
 SyS_bpf+0x2188/0x46a0 kernel/bpf/syscall.c:1451
 entry_SYSCALL_64_fastpath+0x1f/0xbe

Fixes: f3f1c054 ("bpf: Introduce bpf_map ID")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      930651a7
    • T
      tracing: Fix trace_pipe behavior for instance traces · 75df6e68
      由 Tahsin Erdogan 提交于 
      When reading data from trace_pipe, tracing_wait_pipe() performs a
check to see if tracing has been turned off after some data was read.
Currently, this check always looks at global trace state, but it
should be checking the trace instance where trace_pipe is located at.

Because of this bug, cat instances/i1/trace_pipe in the following
script will immediately exit instead of waiting for data:

cd /sys/kernel/debug/tracing
echo 0 > tracing_on
mkdir -p instances/i1
echo 1 > instances/i1/tracing_on
echo 1 > instances/i1/events/sched/sched_process_exec/enable
cat instances/i1/trace_pipe

Link: http://lkml.kernel.org/r/20170917102348.1615-1-tahsin@google.com

Cc: stable@vger.kernel.org
Fixes: 10246fa3 ("tracing: give easy way to clear trace buffer")
Signed-off-by: NTahsin Erdogan <tahsin@google.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
      75df6e68
    • Z
      tracing: Ignore mmiotrace from kernel commandline · c7b3ae0b
      由 Ziqian SUN (Zamir) 提交于 
      The mmiotrace tracer cannot be enabled with ftrace=mmiotrace in kernel
commandline. With this patch, noboot is added to the tracer struct,
and when system boot with a tracer that has noboot=true, it will print
out a warning message and continue booting.

Link: http://lkml.kernel.org/r/1505111195-31942-1-git-send-email-zsun@redhat.comSigned-off-by: NZiqian SUN (Zamir) <zsun@redhat.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
      c7b3ae0b
    • B
      tracing: Erase irqsoff trace with empty write · 8dd33bcb
      由 Bo Yan 提交于 
      One convenient way to erase trace is "echo > trace". However, this
is currently broken if the current tracer is irqsoff tracer. This
is because irqsoff tracer use max_buffer as the default trace
buffer.

Set the max_buffer as the one to be cleared when it's the trace
buffer currently in use.

Link: http://lkml.kernel.org/r/1505754215-29411-1-git-send-email-byan@nvidia.com

Cc: <mingo@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 4acd4d00 ("tracing: give easy way to clear trace buffer")
Signed-off-by: NBo Yan <byan@nvidia.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
      8dd33bcb
  13. 19 9月, 2017 1 次提交
  15. 17 9月, 2017 1 次提交
    • T
      genirq: Fix cpumask check in __irq_startup_managed() · 9cb067ef
      由 Thomas Gleixner 提交于 
      The result of cpumask_any_and() is invalid when result greater or equal
nr_cpu_ids. The current check is checking for greater only. Fix it.

Fixes: 761ea388 ("genirq: Handle managed irqs gracefully in irq_startup()")
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Chen Yu <yu.c.chen@intel.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Alok Kataria <akataria@vmware.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: stable@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rui Zhang <rui.zhang@intel.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Len Brown <lenb@kernel.org>
Link: http://lkml.kernel.org/r/20170913213152.272283444@linutronix.de
      9cb067ef
  17. 16 9月, 2017 1 次提交
  19. 15 9月, 2017 2 次提交
    • T
      sched/wait: Introduce wakeup boomark in wake_up_page_bit · 11a19c7b
      由 Tim Chen 提交于 
      Now that we have added breaks in the wait queue scan and allow bookmark
on scan position, we put this logic in the wake_up_page_bit function.

We can have very long page wait list in large system where multiple
pages share the same wait list. We break the wake up walk here to allow
other cpus a chance to access the list, and not to disable the interrupts
when traversing the list for too long.  This reduces the interrupt and
rescheduling latency, and excessive page wait queue lock hold time.

[ v2: Remove bookmark_wake_function ]
Signed-off-by: NTim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      11a19c7b
    • T
      sched/wait: Break up long wake list walk · 2554db91
      由 Tim Chen 提交于 
      We encountered workloads that have very long wake up list on large
systems. A waker takes a long time to traverse the entire wake list and
execute all the wake functions.

We saw page wait list that are up to 3700+ entries long in tests of
large 4 and 8 socket systems. It took 0.8 sec to traverse such list
during wake up. Any other CPU that contends for the list spin lock will
spin for a long time. It is a result of the numa balancing migration of
hot pages that are shared by many threads.

Multiple CPUs waking are queued up behind the lock, and the last one
queued has to wait until all CPUs did all the wakeups.

The page wait list is traversed with interrupt disabled, which caused
various problems. This was the original cause that triggered the NMI
watch dog timer in: https://patchwork.kernel.org/patch/9800303/ . Only
extending the NMI watch dog timer there helped.

This patch bookmarks the waker's scan position in wake list and break
the wake up walk, to allow access to the list before the waker resume
its walk down the rest of the wait list. It lowers the interrupt and
rescheduling latency.

This patch also provides a performance boost when combined with the next
patch to break up page wakeup list walk. We saw 22% improvement in the
will-it-scale file pread2 test on a Xeon Phi system running 256 threads.

[ v2: Merged in Linus' changes to remove the bookmark_wake_function, and
  simply access to flags. ]
Reported-by: NKan Liang <kan.liang@intel.com>
Tested-by: NKan Liang <kan.liang@intel.com>
Signed-off-by: NTim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      2554db91
  21. 14 9月, 2017 1 次提交
    • M
      mm: treewide: remove GFP_TEMPORARY allocation flag · 0ee931c4
      由 Michal Hocko 提交于 
      GFP_TEMPORARY was introduced by commit e12ba74d ("Group short-lived
and reclaimable kernel allocations") along with __GFP_RECLAIMABLE.  It's
primary motivation was to allow users to tell that an allocation is
short lived and so the allocator can try to place such allocations close
together and prevent long term fragmentation.  As much as this sounds
like a reasonable semantic it becomes much less clear when to use the
highlevel GFP_TEMPORARY allocation flag.  How long is temporary? Can the
context holding that memory sleep? Can it take locks? It seems there is
no good answer for those questions.

The current implementation of GFP_TEMPORARY is basically GFP_KERNEL |
__GFP_RECLAIMABLE which in itself is tricky because basically none of
the existing caller provide a way to reclaim the allocated memory.  So
this is rather misleading and hard to evaluate for any benefits.

I have checked some random users and none of them has added the flag
with a specific justification.  I suspect most of them just copied from
other existing users and others just thought it might be a good idea to
use without any measuring.  This suggests that GFP_TEMPORARY just
motivates for cargo cult usage without any reasoning.

I believe that our gfp flags are quite complex already and especially
those with highlevel semantic should be clearly defined to prevent from
confusion and abuse.  Therefore I propose dropping GFP_TEMPORARY and
replace all existing users to simply use GFP_KERNEL.  Please note that
SLAB users with shrinkers will still get __GFP_RECLAIMABLE heuristic and
so they will be placed properly for memory fragmentation prevention.

I can see reasons we might want some gfp flag to reflect shorterm
allocations but I propose starting from a clear semantic definition and
only then add users with proper justification.

This was been brought up before LSF this year by Matthew [1] and it
turned out that GFP_TEMPORARY really doesn't have a clear semantic.  It
seems to be a heuristic without any measured advantage for most (if not
all) its current users.  The follow up discussion has revealed that
opinions on what might be temporary allocation differ a lot between
developers.  So rather than trying to tweak existing users into a
semantic which they haven't expected I propose to simply remove the flag
and start from scratch if we really need a semantic for short term
allocations.

[1] http://lkml.kernel.org/r/20170118054945.GD18349@bombadil.infradead.org

[akpm@linux-foundation.org: fix typo]
[akpm@linux-foundation.org: coding-style fixes]
[sfr@canb.auug.org.au: drm/i915: fix up]
  Link: http://lkml.kernel.org/r/20170816144703.378d4f4d@canb.auug.org.au
Link: http://lkml.kernel.org/r/20170728091904.14627-1-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Acked-by: NMel Gorman <mgorman@suse.de>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Neil Brown <neilb@suse.de>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      0ee931c4
  23. 12 9月, 2017 5 次提交
  25. 11 9月, 2017 1 次提交
  27. 09 9月, 2017 12 次提交