mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2025-03-10 01:21:40 +07:00
a83836dbc5
In guests without hotplugagble memory drmem structure is only zero
initialized. Trying to manipulate DLPAR parameters results in a crash.
$ echo "memory add count 1" > /sys/kernel/dlpar
Oops: Kernel access of bad area, sig: 11 [#1]
LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
...
NIP: c0000000000ff294 LR: c0000000000ff248 CTR: 0000000000000000
REGS: c0000000fb9d3880 TRAP: 0300 Tainted: G E (5.5.0-rc6-2-default)
MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE> CR: 28242428 XER: 20000000
CFAR: c0000000009a6c10 DAR: 0000000000000010 DSISR: 40000000 IRQMASK: 0
...
NIP dlpar_memory+0x6e4/0xd00
LR dlpar_memory+0x698/0xd00
Call Trace:
dlpar_memory+0x698/0xd00 (unreliable)
handle_dlpar_errorlog+0xc0/0x190
dlpar_store+0x198/0x4a0
kobj_attr_store+0x30/0x50
sysfs_kf_write+0x64/0x90
kernfs_fop_write+0x1b0/0x290
__vfs_write+0x3c/0x70
vfs_write+0xd0/0x260
ksys_write+0xdc/0x130
system_call+0x5c/0x68
Taking closer look at the code, I can see that for_each_drmem_lmb is a
macro expanding into `for (lmb = &drmem_info->lmbs[0]; lmb <=
&drmem_info->lmbs[drmem_info->n_lmbs - 1]; lmb++)`. When drmem_info->lmbs
is NULL, the loop would iterate through the whole address range if it
weren't stopped by the NULL pointer dereference on the next line.
This patch aligns for_each_drmem_lmb and for_each_drmem_lmb_in_range
macro behavior with the common C semantics, where the end marker does
not belong to the scanned range, and alters get_lmb_range() semantics.
As a side effect, the wraparound observed in the crash is prevented.
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| 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.
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.