Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.
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Pull Xtensa fixes from Max Filippov:
"Two fixes for reserved memory/DMA buffers allocation in high memory on
xtensa architecture
- fix memory accounting when reserved memory is in high memory region
- fix DMA allocation from high memory"
* tag 'xtensa-20180225' of git://github.com/jcmvbkbc/linux-xtensa:
xtensa: support DMA buffers in high memory
xtensa: fix high memory/reserved memory collision
Pull x86 fixes from Thomas Gleixner:
"A small set of fixes:
- UAPI data type correction for hyperv
- correct the cpu cores field in /proc/cpuinfo on CPU hotplug
- return proper error code in the resctrl file system failure path to
avoid silent subsequent failures
- correct a subtle accounting issue in the new vector allocation code
which went unnoticed for a while and caused suspend/resume
failures"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/topology: Update the 'cpu cores' field in /proc/cpuinfo correctly across CPU hotplug operations
x86/topology: Fix function name in documentation
x86/intel_rdt: Fix incorrect returned value when creating rdgroup sub-directory in resctrl file system
x86/apic/vector: Handle vector release on CPU unplug correctly
genirq/matrix: Handle CPU offlining proper
x86/headers/UAPI: Use __u64 instead of u64 in <uapi/asm/hyperv.h>
If a DMA buffer is allocated in high memory and kernel mapping is
required use dma_common_contiguous_remap to map buffer to the vmalloc
region and dma_common_free_remap to unmap it.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Pull perf fix from Thomas Gleixner:
"A single commit which shuts up a bogus GCC-8 warning"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/oprofile: Fix bogus GCC-8 warning in nmi_setup()
Without this fix, /proc/cpuinfo will display an incorrect amount
of CPU cores, after bringing them offline and online again, as
exemplified below:
$ cat /proc/cpuinfo | grep cores
cpu cores : 4
cpu cores : 8
cpu cores : 8
cpu cores : 20
cpu cores : 4
cpu cores : 3
cpu cores : 2
cpu cores : 2
This patch fixes this by always zeroing the booted_cores variable
upon turning off a logical CPU.
Tested-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
Signed-off-by: Samuel Neves <sneves@dei.uc.pt>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: jgross@suse.com
Cc: luto@kernel.org
Cc: prarit@redhat.com
Cc: vkuznets@redhat.com
Link: http://lkml.kernel.org/r/20180221205036.5244-1-sneves@dei.uc.pt
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Xtensa memory initialization code frees high memory pages without
checking whether they are in the reserved memory regions or not. That
results in invalid value of totalram_pages and duplicate page usage by
CMA and highmem. It produces a bunch of BUGs at startup looking like
this:
BUG: Bad page state in process swapper pfn:70800
page:be60c000 count:0 mapcount:-127 mapping: (null) index:0x1
flags: 0x80000000()
raw: 80000000 00000000 00000001 ffffff80 00000000 be60c014 be60c014 0000000a
page dumped because: nonzero mapcount
Modules linked in:
CPU: 0 PID: 1 Comm: swapper Tainted: G B 4.16.0-rc1-00015-g7928b2cbe55b-dirty #23
Stack:
bd839d33 00000000 00000018 ba97b64c a106578c bd839d70 be60c000 00000000
a1378054 bd86a000 00000003 ba97b64c a1066166 bd839da0 be60c000 ffe00000
a1066b58 bd839dc0 be504000 00000000 000002f4 bd838000 00000000 0000001e
Call Trace:
[<a1065734>] bad_page+0xac/0xd0
[<a106578c>] free_pages_check_bad+0x34/0x4c
[<a1066166>] __free_pages_ok+0xae/0x14c
[<a1066b58>] __free_pages+0x30/0x64
[<a1365de5>] init_cma_reserved_pageblock+0x35/0x44
[<a13682dc>] cma_init_reserved_areas+0xf4/0x148
[<a10034b8>] do_one_initcall+0x80/0xf8
[<a1361c16>] kernel_init_freeable+0xda/0x13c
[<a125b59d>] kernel_init+0x9/0xd0
[<a1004304>] ret_from_kernel_thread+0xc/0x18
Only free high memory pages that are not reserved.
Cc: stable@vger.kernel.org
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Pull locking fixes from Thomas Gleixner:
"Three patches to fix memory ordering issues on ALPHA and a comment to
clarify the usage scope of a mutex internal function"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/xchg/alpha: Fix xchg() and cmpxchg() memory ordering bugs
locking/xchg/alpha: Clean up barrier usage by using smp_mb() in place of __ASM__MB
locking/xchg/alpha: Add unconditional memory barrier to cmpxchg()
locking/mutex: Add comment to __mutex_owner() to deter usage
GCC-8 shows a warning for the x86 oprofile code that copies per-CPU
data from CPU 0 to all other CPUs, which when building a non-SMP
kernel turns into a memcpy() with identical source and destination
pointers:
arch/x86/oprofile/nmi_int.c: In function 'mux_clone':
arch/x86/oprofile/nmi_int.c:285:2: error: 'memcpy' source argument is the same as destination [-Werror=restrict]
memcpy(per_cpu(cpu_msrs, cpu).multiplex,
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
per_cpu(cpu_msrs, 0).multiplex,
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
sizeof(struct op_msr) * model->num_virt_counters);
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/x86/oprofile/nmi_int.c: In function 'nmi_setup':
arch/x86/oprofile/nmi_int.c:466:3: error: 'memcpy' source argument is the same as destination [-Werror=restrict]
arch/x86/oprofile/nmi_int.c:470:3: error: 'memcpy' source argument is the same as destination [-Werror=restrict]
I have analyzed a number of such warnings now: some are valid and the
GCC warning is welcome. Others turned out to be false-positives, and
GCC was changed to not warn about those any more. This is a corner case
that is a false-positive but the GCC developers feel it's better to keep
warning about it.
In this case, it seems best to work around it by telling GCC
a little more clearly that this code path is never hit with
an IS_ENABLED() configuration check.
Cc:stable as we also want old kernels to build cleanly with GCC-8.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Sebor <msebor@gcc.gnu.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Richter <rric@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: oprofile-list@lists.sf.net
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20180220205826.2008875-1-arnd@arndb.de
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84095
Signed-off-by: Ingo Molnar <mingo@kernel.org>
topology_sibling_cpumask() is the correct thread-related topology
function in the kernel:
s/topology_sibling_mask/topology_sibling_cpumask
Signed-off-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: corbet@lwn.net
Cc: linux-doc@vger.kernel.org
Link: http://lkml.kernel.org/r/20180222084812.14497-1-douly.fnst@cn.fujitsu.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull cleanup patchlet from Thomas Gleixner:
"A single commit removing a bunch of bogus double semicolons all over
the tree"
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
treewide/trivial: Remove ';;$' typo noise
Successful RMW operations are supposed to be fully ordered, but
Alpha's xchg() and cmpxchg() do not meet this requirement.
Will Deacon noticed the bug:
> So MP using xchg:
>
> WRITE_ONCE(x, 1)
> xchg(y, 1)
>
> smp_load_acquire(y) == 1
> READ_ONCE(x) == 0
>
> would be allowed.
... which thus violates the above requirement.
Fix it by adding a leading smp_mb() to the xchg() and cmpxchg() implementations.
Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-alpha@vger.kernel.org
Link: http://lkml.kernel.org/r/1519291488-5752-1-git-send-email-parri.andrea@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>