mainlining shenanigans
b6c84ba22f
Currently we see a kernel-oops reported on Power-9 while attaching a
context to an AFU, with radix-mode and sysfs attr 'prefault_mode' set
to anything other than 'none'. The backtrace of the oops is of this
form:
Unable to handle kernel paging request for data at address 0x00000080
Faulting instruction address: 0xc00800000bcf3b20
cpu 0x1: Vector: 300 (Data Access) at [c00000037f003800]
pc: c00800000bcf3b20: cxl_load_segment+0x178/0x290 [cxl]
lr: c00800000bcf39f0: cxl_load_segment+0x48/0x290 [cxl]
sp: c00000037f003a80
msr: 9000000000009033
dar: 80
dsisr: 40000000
current = 0xc00000037f280000
paca = 0xc0000003ffffe600 softe: 3 irq_happened: 0x01
pid = 3529, comm = afp_no_int
<snip>
cxl_prefault+0xfc/0x248 [cxl]
process_element_entry_psl9+0xd8/0x1a0 [cxl]
cxl_attach_dedicated_process_psl9+0x44/0x130 [cxl]
native_attach_process+0xc0/0x130 [cxl]
afu_ioctl+0x3f4/0x5e0 [cxl]
do_vfs_ioctl+0xdc/0x890
ksys_ioctl+0x68/0xf0
sys_ioctl+0x40/0xa0
system_call+0x58/0x6c
The issue is caused as on Power-8 the AFU attr 'prefault_mode' was
used to improve initial storage fault performance by prefaulting
process segments. However on Power-9 with radix mode we don't have
Storage-Segments that we can prefault. Also prefaulting process Pages
will be too costly and fine-grained.
Hence, since the prefaulting mechanism doesn't makes sense of
radix-mode, this patch updates prefault_mode_store() to not allow any
other value apart from CXL_PREFAULT_NONE when radix mode is enabled.
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| 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.
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.