f77cb0471e
[ Upstream commit 78a509fba9c9b1fcb77f95b7c6be30da3d24823a ] When there are two racing NMIs on x86, the first NMI invokes NMI handler and the 2nd NMI is latched until IRET is executed. If panic on NMI and panic kexec are enabled, the first NMI triggers panic and starts booting the next kernel via kexec. Note that the 2nd NMI is still latched. During the early boot of the next kernel, once an IRET is executed as a result of a page fault, then the 2nd NMI is unlatched and invokes the NMI handler. However, NMI handler is not set up at the early stage of boot, which results in a boot failure. Avoid such problems by setting up a NOP handler for early NMIs. [ mingo: Refined the changelog. ] Signed-off-by: Jun'ichi Nomura <junichi.nomura@nec.com> Signed-off-by: Derek Barbosa <debarbos@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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.