be65e2595b
- 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. -----BEGIN PGP SIGNATURE----- iIoEABYIADIWIQRRSw7ePDh/lE+zeZMp5XQQmuv6qgUCW5FM2hQccm9zdGVkdEBn b29kbWlzLm9yZwAKCRAp5XQQmuv6qqdLAP4/M46VXnwt8hZ0g7K0Cc4M3MwkLnNT xWN3yNSydd/VTAEA13JXiJoKuGTCrYLet+xcvhQxoGsITUrgL+ADJMRy9ww= =h3hB -----END PGP SIGNATURE----- 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 |
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arch | ||
block | ||
certs | ||
crypto | ||
Documentation | ||
drivers | ||
firmware | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
LICENSES | ||
mm | ||
net | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.clang-format | ||
.cocciconfig | ||
.get_maintainer.ignore | ||
.gitattributes | ||
.gitignore | ||
.mailmap | ||
COPYING | ||
CREDITS | ||
Kbuild | ||
Kconfig | ||
MAINTAINERS | ||
Makefile | ||
README |
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.