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  1. 30 1月, 2017 1 次提交
    • D
      perf/core: Make cgroup switch visit only cpuctxs with cgroup events · 058fe1c0
      由 David Carrillo-Cisneros 提交于 
      This patch follows from a conversation in CQM/CMT's last series about
speeding up the context switch for cgroup events:

  https://patchwork.kernel.org/patch/9478617/

This is a low-hanging fruit optimization. It replaces the iteration over
the "pmus" list in cgroup switch by an iteration over a new list that
contains only cpuctxs with at least one cgroup event.

This is necessary because the number of PMUs have increased over the years
e.g modern x86 server systems have well above 50 PMUs.

The iteration over the full PMU list is unneccessary and can be costly in
heavy cache contention scenarios.

Below are some instrumentation measurements with 10, 50 and 90 percentiles
of the total cost of context switch before and after this optimization for
a simple array read/write microbenchark.

  Contention
    Level    Nr events      Before (us)            After (us)       Median
  L2    L3     types      (10%, 50%, 90%)       (10%, 50%, 90%     Speedup
  --------------------------------------------------------------------------
  Low   Low       1       (1.72, 2.42, 5.85)    (1.35, 1.64, 5.46)     29%
  High  Low       1       (2.08, 4.56, 19.8)    (1720, 2.20, 13.7)     51%
  High  High      1       (2.86, 10.4, 12.7)    (2.54, 4.32, 12.1)     58%

  Low   Low       2       (1.98, 3.20, 6.89)    (1.68, 2.41, 8.89)     24%
  High  Low       2       (2.48, 5.28, 22.4)    (2150, 3.69, 14.6)     30%
  High  High      2       (3.32, 8.09, 13.9)    (2.80, 5.15, 13.7)     36%

where:

  1 event type  = cycles
  2 event types = cycles,intel_cqm/llc_occupancy/

   Contention L2 Low: workset  <  L2 cache size.
                 High:  "     >>  L2   "     " .
   Contention L3 Low: workset of task on all sockets  <  L3 cache size.
                 High:   "     "   "   "   "    "    >>  L3   "     " .

   Median Speedup is (50%ile Before - 50%ile After) /  50%ile Before

Unsurprisingly, the benefits of this optimization decrease with the number
of cpuctxs with a cgroup events, yet, is never detrimental.
Tested-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NDavid Carrillo-Cisneros <davidcc@google.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NMark Rutland <mark.rutland@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Cc: Vince Weaver <vince@deater.net>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/20170118192454.58008-2-davidcc@google.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      058fe1c0
  3. 28 1月, 2017 1 次提交
  5. 27 1月, 2017 1 次提交
  7. 26 1月, 2017 3 次提交
  9. 25 1月, 2017 12 次提交
  11. 21 1月, 2017 1 次提交
  13. 20 1月, 2017 1 次提交
  15. 19 1月, 2017 3 次提交
    • L
      gpio: provide lockdep keys for nested/unnested irqchips · 739e6f59
      由 Linus Walleij 提交于 
      The helper function for adding a GPIO chip compiles in a lockdep
key for debugging, the same key is needed for nested chips as
well.

The macro construction is unreadable, replace this with two
static inlines instead.

The _gpiochip_irqchip_add prefixed function is not helpful,
rename it with gpiochip_irqchip_add_key() that tell us what the
function is actually doing.

Fixes: d245b3f9 ("gpio: simplify adding threaded interrupts")
Cc: Roger Quadros <rogerq@ti.com>
Reported-by: NClemens Gruber <clemens.gruber@pqgruber.com>
Reported-by: NRoger Quadros <rogerq@ti.com>
Reported-by: NGrygorii Strashko <grygorii.strashko@ti.com>
Tested-by: NClemens Gruber <clemens.gruber@pqgruber.com>
Tested-by: NGrygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>
      739e6f59
    • D
      bpf: don't trigger OOM killer under pressure with map alloc · d407bd25
      由 Daniel Borkmann 提交于 
      This patch adds two helpers, bpf_map_area_alloc() and bpf_map_area_free(),
that are to be used for map allocations. Using kmalloc() for very large
allocations can cause excessive work within the page allocator, so i) fall
back earlier to vmalloc() when the attempt is considered costly anyway,
and even more importantly ii) don't trigger OOM killer with any of the
allocators.

Since this is based on a user space request, for example, when creating
maps with element pre-allocation, we really want such requests to fail
instead of killing other user space processes.

Also, don't spam the kernel log with warnings should any of the allocations
fail under pressure. Given that, we can make backend selection in
bpf_map_area_alloc() generic, and convert all maps over to use this API
for spots with potentially large allocation requests.

Note, replacing the one kmalloc_array() is fine as overflow checks happen
earlier in htab_map_alloc(), since it must also protect the multiplication
for vmalloc() should kmalloc_array() fail.
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      d407bd25
    • D
      lwtunnel: fix autoload of lwt modules · 9ed59592
      由 David Ahern 提交于 
      Trying to add an mpls encap route when the MPLS modules are not loaded
hangs. For example:

    CONFIG_MPLS=y
    CONFIG_NET_MPLS_GSO=m
    CONFIG_MPLS_ROUTING=m
    CONFIG_MPLS_IPTUNNEL=m

    $ ip route add 10.10.10.10/32 encap mpls 100 via inet 10.100.1.2

The ip command hangs:
root       880   826  0 21:25 pts/0    00:00:00 ip route add 10.10.10.10/32 encap mpls 100 via inet 10.100.1.2

    $ cat /proc/880/stack
    [<ffffffff81065a9b>] call_usermodehelper_exec+0xd6/0x134
    [<ffffffff81065efc>] __request_module+0x27b/0x30a
    [<ffffffff814542f6>] lwtunnel_build_state+0xe4/0x178
    [<ffffffff814aa1e4>] fib_create_info+0x47f/0xdd4
    [<ffffffff814ae451>] fib_table_insert+0x90/0x41f
    [<ffffffff814a8010>] inet_rtm_newroute+0x4b/0x52
    ...

modprobe is trying to load rtnl-lwt-MPLS:

root       881     5  0 21:25 ?        00:00:00 /sbin/modprobe -q -- rtnl-lwt-MPLS

and it hangs after loading mpls_router:

    $ cat /proc/881/stack
    [<ffffffff81441537>] rtnl_lock+0x12/0x14
    [<ffffffff8142ca2a>] register_netdevice_notifier+0x16/0x179
    [<ffffffffa0033025>] mpls_init+0x25/0x1000 [mpls_router]
    [<ffffffff81000471>] do_one_initcall+0x8e/0x13f
    [<ffffffff81119961>] do_init_module+0x5a/0x1e5
    [<ffffffff810bd070>] load_module+0x13bd/0x17d6
    ...

The problem is that lwtunnel_build_state is called with rtnl lock
held preventing mpls_init from registering.

Given the potential references held by the time lwtunnel_build_state it
can not drop the rtnl lock to the load module. So, extract the module
loading code from lwtunnel_build_state into a new function to validate
the encap type. The new function is called while converting the user
request into a fib_config which is well before any table, device or
fib entries are examined.

Fixes: 745041e2 ("lwtunnel: autoload of lwt modules")
Signed-off-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      9ed59592
  17. 18 1月, 2017 2 次提交
  19. 17 1月, 2017 3 次提交
  21. 16 1月, 2017 3 次提交
  23. 15 1月, 2017 2 次提交
    • P
      rcu: Narrow early boot window of illegal synchronous grace periods · 52d7e48b
      由 Paul E. McKenney 提交于 
      The current preemptible RCU implementation goes through three phases
during bootup.  In the first phase, there is only one CPU that is running
with preemption disabled, so that a no-op is a synchronous grace period.
In the second mid-boot phase, the scheduler is running, but RCU has
not yet gotten its kthreads spawned (and, for expedited grace periods,
workqueues are not yet running.  During this time, any attempt to do
a synchronous grace period will hang the system (or complain bitterly,
depending).  In the third and final phase, RCU is fully operational and
everything works normally.

This has been OK for some time, but there has recently been some
synchronous grace periods showing up during the second mid-boot phase.
This code worked "by accident" for awhile, but started failing as soon
as expedited RCU grace periods switched over to workqueues in commit
8b355e3b ("rcu: Drive expedited grace periods from workqueue").
Note that the code was buggy even before this commit, as it was subject
to failure on real-time systems that forced all expedited grace periods
to run as normal grace periods (for example, using the rcu_normal ksysfs
parameter).  The callchain from the failure case is as follows:

early_amd_iommu_init()
|-> acpi_put_table(ivrs_base);
|-> acpi_tb_put_table(table_desc);
|-> acpi_tb_invalidate_table(table_desc);
|-> acpi_tb_release_table(...)
|-> acpi_os_unmap_memory
|-> acpi_os_unmap_iomem
|-> acpi_os_map_cleanup
|-> synchronize_rcu_expedited

The kernel showing this callchain was built with CONFIG_PREEMPT_RCU=y,
which caused the code to try using workqueues before they were
initialized, which did not go well.

This commit therefore reworks RCU to permit synchronous grace periods
to proceed during this mid-boot phase.  This commit is therefore a
fix to a regression introduced in v4.9, and is therefore being put
forward post-merge-window in v4.10.

This commit sets a flag from the existing rcu_scheduler_starting()
function which causes all synchronous grace periods to take the expedited
path.  The expedited path now checks this flag, using the requesting task
to drive the expedited grace period forward during the mid-boot phase.
Finally, this flag is updated by a core_initcall() function named
rcu_exp_runtime_mode(), which causes the runtime codepaths to be used.

Note that this arrangement assumes that tasks are not sent POSIX signals
(or anything similar) from the time that the first task is spawned
through core_initcall() time.

Fixes: 8b355e3b ("rcu: Drive expedited grace periods from workqueue")
Reported-by: N"Zheng, Lv" <lv.zheng@intel.com>
Reported-by: NBorislav Petkov <bp@alien8.de>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: NStan Kain <stan.kain@gmail.com>
Tested-by: NIvan <waffolz@hotmail.com>
Tested-by: NEmanuel Castelo <emanuel.castelo@gmail.com>
Tested-by: NBruno Pesavento <bpesavento@infinito.it>
Tested-by: NBorislav Petkov <bp@suse.de>
Tested-by: NFrederic Bezies <fredbezies@gmail.com>
Cc: <stable@vger.kernel.org> # 4.9.0-
      52d7e48b
    • D
      coredump: Ensure proper size of sparse core files · 4d22c75d
      由 Dave Kleikamp 提交于 
      If the last section of a core file ends with an unmapped or zero page,
the size of the file does not correspond with the last dump_skip() call.
gdb complains that the file is truncated and can be confusing to users.

After all of the vma sections are written, make sure that the file size
is no smaller than the current file position.

This problem can be demonstrated with gdb's bigcore testcase on the
sparc architecture.
Signed-off-by: NDave Kleikamp <dave.kleikamp@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      4d22c75d
  25. 14 1月, 2017 5 次提交
    • P
      efi/x86: Prune invalid memory map entries and fix boot regression · 0100a3e6
      由 Peter Jones 提交于 
      Some machines, such as the Lenovo ThinkPad W541 with firmware GNET80WW
(2.28), include memory map entries with phys_addr=0x0 and num_pages=0.

These machines fail to boot after the following commit,

  commit 8e80632f ("efi/esrt: Use efi_mem_reserve() and avoid a kmalloc()")

Fix this by removing such bogus entries from the memory map.

Furthermore, currently the log output for this case (with efi=debug)
looks like:

 [    0.000000] efi: mem45: [Reserved           |   |  |  |  |  |  |  |  |  |  |  |  ] range=[0x0000000000000000-0xffffffffffffffff] (0MB)

This is clearly wrong, and also not as informative as it could be.  This
patch changes it so that if we find obviously invalid memory map
entries, we print an error and skip those entries.  It also detects the
display of the address range calculation overflow, so the new output is:

 [    0.000000] efi: [Firmware Bug]: Invalid EFI memory map entries:
 [    0.000000] efi: mem45: [Reserved           |   |  |  |  |  |  |  |   |  |  |  |  ] range=[0x0000000000000000-0x0000000000000000] (invalid)

It also detects memory map sizes that would overflow the physical
address, for example phys_addr=0xfffffffffffff000 and
num_pages=0x0200000000000001, and prints:

 [    0.000000] efi: [Firmware Bug]: Invalid EFI memory map entries:
 [    0.000000] efi: mem45: [Reserved           |   |  |  |  |  |  |  |   |  |  |  |  ] range=[phys_addr=0xfffffffffffff000-0x20ffffffffffffffff] (invalid)

It then removes these entries from the memory map.
Signed-off-by: NPeter Jones <pjones@redhat.com>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
[ardb: refactor for clarity with no functional changes, avoid PAGE_SHIFT]
Signed-off-by: NMatt Fleming <matt@codeblueprint.co.uk>
[Matt: Include bugzilla info in commit log]
Cc: <stable@vger.kernel.org> # v4.9+
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=191121Signed-off-by: NIngo Molnar <mingo@kernel.org>
      0100a3e6
    • J
      perf/x86/intel: Account interrupts for PEBS errors · 475113d9
      由 Jiri Olsa 提交于 
      It's possible to set up PEBS events to get only errors and not
any data, like on SNB-X (model 45) and IVB-EP (model 62)
via 2 perf commands running simultaneously:

    taskset -c 1 ./perf record -c 4 -e branches:pp -j any -C 10

This leads to a soft lock up, because the error path of the
intel_pmu_drain_pebs_nhm() does not account event->hw.interrupt
for error PEBS interrupts, so in case you're getting ONLY
errors you don't have a way to stop the event when it's over
the max_samples_per_tick limit:

  NMI watchdog: BUG: soft lockup - CPU#22 stuck for 22s! [perf_fuzzer:5816]
  ...
  RIP: 0010:[<ffffffff81159232>]  [<ffffffff81159232>] smp_call_function_single+0xe2/0x140
  ...
  Call Trace:
   ? trace_hardirqs_on_caller+0xf5/0x1b0
   ? perf_cgroup_attach+0x70/0x70
   perf_install_in_context+0x199/0x1b0
   ? ctx_resched+0x90/0x90
   SYSC_perf_event_open+0x641/0xf90
   SyS_perf_event_open+0x9/0x10
   do_syscall_64+0x6c/0x1f0
   entry_SYSCALL64_slow_path+0x25/0x25

Add perf_event_account_interrupt() which does the interrupt
and frequency checks and call it from intel_pmu_drain_pebs_nhm()'s
error path.

We keep the pending_kill and pending_wakeup logic only in the
__perf_event_overflow() path, because they make sense only if
there's any data to deliver.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.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 <vince@deater.net>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/1482931866-6018-2-git-send-email-jolsa@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      475113d9
    • M
      kprobes, extable: Identify kprobes trampolines as kernel text area · 5b485629
      由 Masami Hiramatsu 提交于 
      Improve __kernel_text_address()/kernel_text_address() to return
true if the given address is on a kprobe's instruction slot
trampoline.

This can help stacktraces to determine the address is on a
text area or not.

To implement this atomically in is_kprobe_*_slot(), also change
the insn_cache page list to an RCU list.

This changes timings a bit (it delays page freeing to the RCU garbage
collection phase), but none of that is in the hot path.

Note: this change can add small overhead to stack unwinders because
it adds 2 additional checks to __kernel_text_address(). However, the
impact should be very small, because kprobe_insn_pages list has 1 entry
per 256 probes(on x86, on arm/arm64 it will be 1024 probes),
and kprobe_optinsn_pages has 1 entry per 32 probes(on x86).
In most use cases, the number of kprobe events may be less
than 20, which means that is_kprobe_*_slot() will check just one entry.
Tested-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/148388747896.6869.6354262871751682264.stgit@devbox
[ Improved the changelog and coding style. ]
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      5b485629
    • C
      block: add blk_rq_payload_bytes · 2e3258ec
      由 Christoph Hellwig 提交于 
      Add a helper to calculate the actual data transfer size for special
payload requests.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NJens Axboe <axboe@fb.com>
      2e3258ec
    • S
      tcp: fix tcp_fastopen unaligned access complaints on sparc · 003c9410
      由 Shannon Nelson 提交于 
      Fix up a data alignment issue on sparc by swapping the order
of the cookie byte array field with the length field in
struct tcp_fastopen_cookie, and making it a proper union
to clean up the typecasting.

This addresses log complaints like these:
    log_unaligned: 113 callbacks suppressed
    Kernel unaligned access at TPC[976490] tcp_try_fastopen+0x2d0/0x360
    Kernel unaligned access at TPC[9764ac] tcp_try_fastopen+0x2ec/0x360
    Kernel unaligned access at TPC[9764c8] tcp_try_fastopen+0x308/0x360
    Kernel unaligned access at TPC[9764e4] tcp_try_fastopen+0x324/0x360
    Kernel unaligned access at TPC[976490] tcp_try_fastopen+0x2d0/0x360

Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NShannon Nelson <shannon.nelson@oracle.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      003c9410
  27. 13 1月, 2017 2 次提交