c90e6fbb22
The problem occurs [1] when a kernel-mode task returns from a system
call with a pending signal.
A real-life scenario is a child of 'khelper' returning from a failed
kernel_execve() in ____call_usermodehelper() [ kernel/kmod.c ].
kernel_execve() fails due to a pending SIGKILL, which is the result of
"kill -9 -1" (at least, busybox's init does it upon reboot).
The loop is as follows:
* syscall_exit_work:
- work_pending: // start_of_the_loop
- work_notifysig:
- do_notify_resume()
- do_signal()
- if (!user_mode(regs)) return;
- resume_userspace // TIF_SIGPENDING is still set
- work_pending // so we call work_pending => goto
// start_of_the_loop
More information can be found in another LKML thread:
http://www.serverphorums.com/read.php?12,457826
[1] The problem was also reproduced on !CONFIG_VM86 x86, and the
following fix was accepted.
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=29a2e2836ff9ea65a603c89df217f4198973a74f
Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/3571/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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| cpufreq | ||
| .gitignore | ||
| 8250-platform.c | ||
| asm-offsets.c | ||
| binfmt_elfn32.c | ||
| binfmt_elfo32.c | ||
| bmips_vec.S | ||
| branch.c | ||
| cevt-bcm1480.c | ||
| cevt-ds1287.c | ||
| cevt-gt641xx.c | ||
| cevt-r4k.c | ||
| cevt-sb1250.c | ||
| cevt-smtc.c | ||
| cevt-txx9.c | ||
| cpu-bugs64.c | ||
| cpu-probe.c | ||
| csrc-bcm1480.c | ||
| csrc-ioasic.c | ||
| csrc-powertv.c | ||
| csrc-r4k.c | ||
| csrc-sb1250.c | ||
| early_printk.c | ||
| entry.S | ||
| ftrace.c | ||
| genex.S | ||
| gpio_txx9.c | ||
| head.S | ||
| i8253.c | ||
| i8259.c | ||
| irq_cpu.c | ||
| irq_txx9.c | ||
| irq-gic.c | ||
| irq-gt641xx.c | ||
| irq-msc01.c | ||
| irq-rm7000.c | ||
| irq-rm9000.c | ||
| irq.c | ||
| jump_label.c | ||
| kgdb.c | ||
| kprobes.c | ||
| linux32.c | ||
| machine_kexec.c | ||
| Makefile | ||
| mcount.S | ||
| mips_ksyms.c | ||
| mips_machine.c | ||
| mips-mt-fpaff.c | ||
| mips-mt.c | ||
| module-rela.c | ||
| module.c | ||
| octeon_switch.S | ||
| perf_event_mipsxx.c | ||
| perf_event.c | ||
| proc.c | ||
| process.c | ||
| prom.c | ||
| ptrace32.c | ||
| ptrace.c | ||
| r4k_fpu.S | ||
| r4k_switch.S | ||
| r2300_fpu.S | ||
| r2300_switch.S | ||
| r6000_fpu.S | ||
| relocate_kernel.S | ||
| reset.c | ||
| rtlx.c | ||
| scall32-o32.S | ||
| scall64-64.S | ||
| scall64-n32.S | ||
| scall64-o32.S | ||
| setup.c | ||
| signal32.c | ||
| signal_n32.c | ||
| signal-common.h | ||
| signal.c | ||
| smp-bmips.c | ||
| smp-cmp.c | ||
| smp-mt.c | ||
| smp-up.c | ||
| smp.c | ||
| smtc-asm.S | ||
| smtc-proc.c | ||
| smtc.c | ||
| spinlock_test.c | ||
| spram.c | ||
| stacktrace.c | ||
| sync-r4k.c | ||
| syscall.c | ||
| time.c | ||
| topology.c | ||
| traps.c | ||
| unaligned.c | ||
| vdso.c | ||
| vmlinux.lds.S | ||
| vpe.c | ||
| watch.c | ||