c0beffc4f4
A kernel crash in process context that calls emergency_restart from
panic will end up calling opal_event_shutdown with interrupts disabled
but not in interrupt. This causes a sleeping function to be called
which gives the following warning with sysrq+c:
Rebooting in 10 seconds..
BUG: sleeping function called from invalid context at kernel/locking/mutex.c:238
in_atomic(): 0, irqs_disabled(): 1, pid: 7669, name: bash
CPU: 20 PID: 7669 Comm: bash Tainted: G D W 4.17.0-rc5+ #3
Call Trace:
dump_stack+0xb0/0xf4 (unreliable)
___might_sleep+0x174/0x1a0
mutex_lock+0x38/0xb0
__free_irq+0x68/0x460
free_irq+0x70/0xc0
opal_event_shutdown+0xb4/0xf0
opal_shutdown+0x24/0xa0
pnv_shutdown+0x28/0x40
machine_shutdown+0x44/0x60
machine_restart+0x28/0x80
emergency_restart+0x30/0x50
panic+0x2a0/0x328
oops_end+0x1ec/0x1f0
bad_page_fault+0xe8/0x154
handle_page_fault+0x34/0x38
--- interrupt: 300 at sysrq_handle_crash+0x44/0x60
LR = __handle_sysrq+0xfc/0x260
flag_spec.62335+0x12b844/0x1e8db4 (unreliable)
__handle_sysrq+0xfc/0x260
write_sysrq_trigger+0xa8/0xb0
proc_reg_write+0xac/0x110
__vfs_write+0x6c/0x240
vfs_write+0xd0/0x240
ksys_write+0x6c/0x110
Fixes: 9f0fd0499d ("powerpc/powernv: Add a virtual irqchip for opal events")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.