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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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| alchemy | ||
| ar7 | ||
| ath79 | ||
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| boot | ||
| cavium-octeon | ||
| cobalt | ||
| configs | ||
| dec | ||
| emma | ||
| fw | ||
| include | ||
| jazz | ||
| jz4740 | ||
| kernel | ||
| lantiq | ||
| lasat | ||
| lib | ||
| loongson | ||
| loongson1 | ||
| math-emu | ||
| mm | ||
| mti-malta | ||
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| netlogic | ||
| oprofile | ||
| pci | ||
| pmc-sierra | ||
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| power | ||
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| sibyte | ||
| sni | ||
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| vr41xx | ||
| wrppmc | ||
| Kbuild | ||
| Kbuild.platforms | ||
| Kconfig | ||
| Kconfig.debug | ||
| Makefile | ||