Linux kernel source tree
1cab5bd69e
There exists the following issue under DEBUG_PREEMPT:
BUG: using smp_processor_id() in preemptible [00000000] code: systemd/1
caller is show_cpuinfo+0x460/0xea0
...
Call Trace:
[<ffffffff8020f0dc>] show_stack+0x94/0x128
[<ffffffff80e6cab4>] dump_stack_lvl+0x94/0xd8
[<ffffffff80e74c5c>] check_preemption_disabled+0x104/0x110
[<ffffffff802209c8>] show_cpuinfo+0x460/0xea0
[<ffffffff80539d54>] seq_read_iter+0xfc/0x4f8
[<ffffffff804fcc10>] new_sync_read+0x110/0x1b8
[<ffffffff804ff57c>] vfs_read+0x1b4/0x1d0
[<ffffffff804ffb18>] ksys_read+0xd0/0x110
[<ffffffff8021c090>] syscall_common+0x34/0x58
We can see the following call trace:
show_cpuinfo()
cpu_has_fpu
current_cpu_data
smp_processor_id()
$ addr2line -f -e vmlinux 0xffffffff802209c8
show_cpuinfo
arch/mips/kernel/proc.c:188
$ head -188 arch/mips/kernel/proc.c | tail -1
if (cpu_has_fpu)
arch/mips/include/asm/cpu-features.h
# define cpu_has_fpu (current_cpu_data.options & MIPS_CPU_FPU)
arch/mips/include/asm/cpu-info.h
#define current_cpu_data cpu_data[smp_processor_id()]
Based on the above analysis, fix the issue by using raw_cpu_has_fpu
which calls raw_smp_processor_id() in show_cpuinfo().
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| 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.
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.