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Linus Torvalds be65e2595b This fixes two bugs:
- The first one is a side effect caused by using SRCU for rcuidle
    tracepoints. It seems that the perf was depending on the rcuidle
    tracepoints to make RCU watch when it wasn't. The real fix will
    bet to have perf use SRCU instead of depending on RCU watching,
    but that can't be done until SRCU is safe to use in NMI context
    (Paul's working on that).
 
  - The second bug fix is for a bug that's been periodically making
    my tests fail randomly for some time. I haven't had time to track
    it down, but finally have. It has to do with stressing NMIs (via perf)
    while enabling or disabling ftrace function handling with lockdep
    enabled. If an interrupt happens and just as it returns, it sets
    lockdep back to "interrupts enabled" but before it returns an NMI
    is triggered, and if this happens while printk_nmi_enter has a
    breakpoint attached to it (because ftrace is converting it to or from
    nop to call fentry), the breakpoint trap also calls into lockdep,
    and since returning from the NMI to a interrupt handler, interrupts
    were disabled when the NMI went off, lockdep keeps its state as
    interrupts disabled when it returns back from the interrupt handler
    where interrupts are enabled. This causes lockdep_assert_irqs_enabled()
    to trigger a false positive.
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Merge tag 'trace-v4.19-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "This fixes two annoying bugs:

   - The first one is a side effect caused by using SRCU for rcuidle
     tracepoints. It seems that the perf was depending on the rcuidle
     tracepoints to make RCU watch when it wasn't.

     The real fix will be to have perf use SRCU instead of depending on
     RCU watching, but that can't be done until SRCU is safe to use in
     NMI context (Paul's working on that).

   - The second bug fix is for a bug that's been periodically making my
     tests fail randomly for some time. I haven't had time to track it
     down, but finally have. It has to do with stressing NMIs (via perf)
     while enabling or disabling ftrace function handling with lockdep
     enabled.

     If an interrupt happens and just as it returns, it sets lockdep
     back to "interrupts enabled" but before it returns an NMI is
     triggered, and if this happens while printk_nmi_enter has a
     breakpoint attached to it (because ftrace is converting it to or
     from nop to call fentry), the breakpoint trap also calls into
     lockdep, and since returning from the NMI to a interrupt handler,
     interrupts were disabled when the NMI went off, lockdep keeps its
     state as interrupts disabled when it returns back from the
     interrupt handler where interrupts are enabled.

     This causes lockdep_assert_irqs_enabled() to trigger a false
     positive"

* tag 'trace-v4.19-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  printk/tracing: Do not trace printk_nmi_enter()
  tracing: Add back in rcu_irq_enter/exit_irqson() for rcuidle tracepoints
2018-09-06 09:06:49 -07:00
arch nds32 patches for 4.19 2018-09-05 09:13:31 -07:00
block block: bsg: move atomic_t ref_count variable to refcount API 2018-08-27 19:17:02 -06:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto DMAengine updates for v4.19-rc1 2018-08-18 15:55:59 -07:00
Documentation SCSI fixes on 20180905 2018-09-05 09:17:20 -07:00
drivers GPIO fixes for the v4.19 cycle: 2018-09-05 09:27:45 -07:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs for-4.19-rc2-tag 2018-09-06 09:04:45 -07:00
include This fixes two bugs: 2018-09-06 09:06:49 -07:00
init Kbuild updates for v4.19 (2nd) 2018-08-25 13:40:38 -07:00
ipc ipc/shm: properly return EIDRM in shm_lock() 2018-09-04 16:45:02 -07:00
kernel This fixes two bugs: 2018-09-06 09:06:49 -07:00
lib lib/Kconfig.debug: fix three typos in help text 2018-09-04 16:45:02 -07:00
LICENSES LICENSES: Add Linux-OpenIB license text 2018-04-27 16:41:53 -06:00
mm mm: fix BUG_ON() in vmf_insert_pfn_pud() from VM_MIXEDMAP removal 2018-09-04 16:45:02 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-09-04 12:45:11 -07:00
samples samples/bpf: all XDP samples should unload xdp/bpf prog on SIGTERM 2018-08-16 21:55:32 +02:00
scripts nds32 patches for 4.19 2018-09-05 09:13:31 -07:00
security uapi/linux/keyctl.h: don't use C++ reserved keyword as a struct member name 2018-09-04 16:45:02 -07:00
sound Merge branch 'akpm' (patches from Andrew) 2018-08-23 19:20:12 -07:00
tools Merge branch 'akpm' (patches from Andrew) 2018-09-04 17:01:11 -07:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt ARM: Support for Group0 interrupts in guests, Cache management 2018-08-22 13:52:44 -07:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS Fix up libata MAINTAINERS entry 2018-08-27 08:07:25 -07:00
Makefile Linux 4.19-rc2 2018-09-02 14:37:30 -07:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.