Revision 90c1cba2b3b3851c151229f61801919b2904d437 authored by Bart Van Assche on 03 April 2019, 23:35:52 UTC, committed by Ingo Molnar on 10 April 2019, 11:45:59 UTC
The following commit: a0b0fd53e1e6 ("locking/lockdep: Free lock classes that are no longer in use") changed the behavior of lockdep_free_key_range() from unconditionally zapping lock classes into only zapping lock classes if debug_lock == true. Not zapping lock classes if debug_lock == false leaves dangling pointers in several lockdep datastructures, e.g. lock_class::name in the all_lock_classes list. The shell command "cat /proc/lockdep" causes the kernel to iterate the all_lock_classes list. Hence the "unable to handle kernel paging request" cash that Shenghui encountered by running cat /proc/lockdep. Since the new behavior can cause cat /proc/lockdep to crash, restore the pre-v5.1 behavior. This patch avoids that cat /proc/lockdep triggers the following crash with debug_lock == false: BUG: unable to handle kernel paging request at fffffbfff40ca448 RIP: 0010:__asan_load1+0x28/0x50 Call Trace: string+0xac/0x180 vsnprintf+0x23e/0x820 seq_vprintf+0x82/0xc0 seq_printf+0x92/0xb0 print_name+0x34/0xb0 l_show+0x184/0x200 seq_read+0x59e/0x6c0 proc_reg_read+0x11f/0x170 __vfs_read+0x4d/0x90 vfs_read+0xc5/0x1f0 ksys_read+0xab/0x130 __x64_sys_read+0x43/0x50 do_syscall_64+0x71/0x210 entry_SYSCALL_64_after_hwframe+0x49/0xbe Reported-by: shenghui <shhuiw@foxmail.com> Signed-off-by: Bart Van Assche <bvanassche@acm.org> 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> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will.deacon@arm.com> Fixes: a0b0fd53e1e6 ("locking/lockdep: Free lock classes that are no longer in use") # v5.1-rc1. Link: https://lkml.kernel.org/r/20190403233552.124673-1-bvanassche@acm.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Kconfig
menuconfig SAMPLES
bool "Sample kernel code"
depends on !UML
help
You can build and test sample kernel code here.
if SAMPLES
config SAMPLE_TRACE_EVENTS
tristate "Build trace_events examples -- loadable modules only"
depends on EVENT_TRACING && m
help
This build trace event example modules.
config SAMPLE_TRACE_PRINTK
tristate "Build trace_printk module - tests various trace_printk formats"
depends on EVENT_TRACING && m
help
This builds a module that calls trace_printk() and can be used to
test various trace_printk() calls from a module.
config SAMPLE_KOBJECT
tristate "Build kobject examples -- loadable modules only"
depends on m
help
This config option will allow you to build a number of
different kobject sample modules showing how to use kobjects,
ksets, and ktypes properly.
If in doubt, say "N" here.
config SAMPLE_KPROBES
tristate "Build kprobes examples -- loadable modules only"
depends on KPROBES && m
help
This build several kprobes example modules.
config SAMPLE_KRETPROBES
tristate "Build kretprobes example -- loadable modules only"
default m
depends on SAMPLE_KPROBES && KRETPROBES
config SAMPLE_HW_BREAKPOINT
tristate "Build kernel hardware breakpoint examples -- loadable module only"
depends on HAVE_HW_BREAKPOINT && m
help
This builds kernel hardware breakpoint example modules.
config SAMPLE_KFIFO
tristate "Build kfifo examples -- loadable modules only"
depends on m
help
This config option will allow you to build a number of
different kfifo sample modules showing how to use the
generic kfifo API.
If in doubt, say "N" here.
config SAMPLE_KDB
tristate "Build kdb command example -- loadable modules only"
depends on KGDB_KDB && m
help
Build an example of how to dynamically add the hello
command to the kdb shell.
config SAMPLE_QMI_CLIENT
tristate "Build qmi client sample -- loadable modules only"
depends on m
depends on ARCH_QCOM
depends on NET
select QCOM_QMI_HELPERS
help
Build an QMI client sample driver, which demonstrates how to
communicate with a remote QRTR service, using QMI encoded messages.
config SAMPLE_RPMSG_CLIENT
tristate "Build rpmsg client sample -- loadable modules only"
depends on RPMSG && m
help
Build an rpmsg client sample driver, which demonstrates how
to communicate with an AMP-configured remote processor over
the rpmsg bus.
config SAMPLE_LIVEPATCH
tristate "Build live patching samples -- loadable modules only"
depends on LIVEPATCH && m
help
Build sample live patch demonstrations.
config SAMPLE_CONFIGFS
tristate "Build configfs patching sample -- loadable modules only"
depends on CONFIGFS_FS && m
help
Builds a sample configfs interface.
config SAMPLE_CONNECTOR
tristate "Build connector sample -- loadable modules only"
depends on CONNECTOR && m
help
When enabled, this builds both a sample kernel module for
the connector interface and a user space tool to communicate
with it.
See also Documentation/connector/connector.txt
config SAMPLE_SECCOMP
tristate "Build seccomp sample code -- loadable modules only"
depends on SECCOMP_FILTER && m
help
Build samples of seccomp filters using various methods of
BPF filter construction.
config SAMPLE_VFIO_MDEV_MTTY
tristate "Build VFIO mtty example mediated device sample code -- loadable modules only"
depends on VFIO_MDEV_DEVICE && m
help
Build a virtual tty sample driver for use as a VFIO
mediated device
config SAMPLE_VFIO_MDEV_MDPY
tristate "Build VFIO mdpy example mediated device sample code -- loadable modules only"
depends on VFIO_MDEV_DEVICE && m
help
Build a virtual display sample driver for use as a VFIO
mediated device. It is a simple framebuffer and supports
the region display interface (VFIO_GFX_PLANE_TYPE_REGION).
config SAMPLE_VFIO_MDEV_MDPY_FB
tristate "Build VFIO mdpy example guest fbdev driver -- loadable module only"
depends on FB && m
select FB_CFB_FILLRECT
select FB_CFB_COPYAREA
select FB_CFB_IMAGEBLIT
help
Guest fbdev driver for the virtual display sample driver.
config SAMPLE_VFIO_MDEV_MBOCHS
tristate "Build VFIO mdpy example mediated device sample code -- loadable modules only"
depends on VFIO_MDEV_DEVICE && m
select DMA_SHARED_BUFFER
help
Build a virtual display sample driver for use as a VFIO
mediated device. It supports the region display interface
(VFIO_GFX_PLANE_TYPE_DMABUF).
Emulate enough of qemu stdvga to make bochs-drm.ko happy.
That is basically the vram memory bar and the bochs dispi
interface vbe registers in the mmio register bar.
Specifically it does *not* include any legacy vga stuff.
Device looks a lot like "qemu -device secondary-vga".
config SAMPLE_ANDROID_BINDERFS
bool "Build Android binderfs example"
depends on CONFIG_ANDROID_BINDERFS
help
Builds a sample program to illustrate the use of the Android binderfs
filesystem.
config SAMPLE_STATX
bool "Build example extended-stat using code"
depends on BROKEN
help
Build example userspace program to use the new extended-stat syscall.
endif # SAMPLES
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