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 perf fixes from Thomas Gleixner:
"Four patches which all address lock inversions and deadlocks in the
perf core code and the Intel debug store"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86: Fix perf,x86,cpuhp deadlock
perf/core: Fix ctx::mutex deadlock
perf/core: Fix another perf,trace,cpuhp lock inversion
perf/core: Fix lock inversion between perf,trace,cpuhp
Pull locking fixes from Thomas Gleixner:
"Two final locking fixes for 4.15:
- Repair the OWNER_DIED logic in the futex code which got wreckaged
with the recent fix for a subtle race condition.
- Prevent the hard lockup detector from triggering when dumping all
held locks in the system"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/lockdep: Avoid triggering hardlockup from debug_show_all_locks()
futex: Fix OWNER_DEAD fixup
More lockdep gifts, a 5-way lockup race:
perf_event_create_kernel_counter()
perf_event_alloc()
perf_try_init_event()
x86_pmu_event_init()
__x86_pmu_event_init()
x86_reserve_hardware()
#0 mutex_lock(&pmc_reserve_mutex);
reserve_ds_buffer()
#1 get_online_cpus()
perf_event_release_kernel()
_free_event()
hw_perf_event_destroy()
x86_release_hardware()
#0 mutex_lock(&pmc_reserve_mutex)
release_ds_buffer()
#1 get_online_cpus()
#1 do_cpu_up()
perf_event_init_cpu()
#2 mutex_lock(&pmus_lock)
#3 mutex_lock(&ctx->mutex)
sys_perf_event_open()
mutex_lock_double()
#3 mutex_lock(ctx->mutex)
#4 mutex_lock_nested(ctx->mutex, 1);
perf_try_init_event()
#4 mutex_lock_nested(ctx->mutex, 1)
x86_pmu_event_init()
intel_pmu_hw_config()
x86_add_exclusive()
#0 mutex_lock(&pmc_reserve_mutex)
Fix it by using ordering constructs instead of locking.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull RISC-V update from Palmer Dabbelt:
"RISC-V: We have a new mailing list and git repo!
Sorry to send something essentially as late as possible (Friday after
an rc9), but we managed to get a mailing list for the RISC-V Linux
port. We've been using patches@groups.riscv.org for a while, but that
list has some problems (it's Google Groups and it's shared over all
RISC-V software projects). The new infaread.org list is much better.
We just got it on Wednesday but I used it a bit on Thursday to shake
out all the configuration problems and it appears to be in working
order.
When I updated the mailing list I noticed that the MAINTAINERS file
was pointing to our github repo, but now that we have a kernel.org
repo I'd like to point to that instead so I changed that as well.
We'll be centralizing all RISC-V Linux related development here as
that seems to be the saner way to go about it.
I can understand if it's too late to get this into 4.15, but given
that it's not a code change I was hoping it'd still be OK. It would be
nice to have the new mailing list and git repo in the release tarballs
so when people start to find bugs they'll get to the right place"
* tag 'riscv-for-linus-4.15-maintainers' of git://git.kernel.org/pub/scm/linux/kernel/git/palmer/riscv-linux:
Update the RISC-V MAINTAINERS file
debug_show_all_locks() iterates all tasks and print held locks whole
holding tasklist_lock. This can take a while on a slow console device
and may end up triggering NMI hardlockup detector if someone else ends
up waiting for tasklist_lock.
Touch the NMI watchdog while printing the held locks to avoid
spuriously triggering the hardlockup detector.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-team@fb.com
Link: http://lkml.kernel.org/r/20180122220055.GB1771050@devbig577.frc2.facebook.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Lockdep noticed the following 3-way lockup scenario:
sys_perf_event_open()
perf_event_alloc()
perf_try_init_event()
#0 ctx = perf_event_ctx_lock_nested(1)
perf_swevent_init()
swevent_hlist_get()
#1 mutex_lock(&pmus_lock)
perf_event_init_cpu()
#1 mutex_lock(&pmus_lock)
#2 mutex_lock(&ctx->mutex)
sys_perf_event_open()
mutex_lock_double()
#2 mutex_lock()
#0 mutex_lock_nested()
And while we need that perf_event_ctx_lock_nested() for HW PMUs such
that they can iterate the sibling list, trying to match it to the
available counters, the software PMUs need do no such thing. Exclude
them.
In particular the swevent triggers the above invertion, while the
tpevent PMU triggers a more elaborate one through their event_mutex.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull networking fixes from David Miller:
1) The per-network-namespace loopback device, and thus its namespace,
can have its teardown deferred for a long time if a kernel created
TCP socket closes and the namespace is exiting meanwhile. The kernel
keeps trying to finish the close sequence until it times out (which
takes quite some time).
Fix this by forcing the socket closed in this situation, from Dan
Streetman.
2) Fix regression where we're trying to invoke the update_pmtu method
on route types (in this case metadata tunnel routes) that don't
implement the dst_ops method. Fix from Nicolas Dichtel.
3) Fix long standing memory corruption issues in r8169 driver by
performing the chip statistics DMA programming more correctly. From
Francois Romieu.
4) Handle local broadcast sends over VRF routes properly, from David
Ahern.
5) Don't refire the DCCP CCID2 timer endlessly, otherwise the socket
can never be released. From Alexey Kodanev.
6) Set poll flags properly in VSOCK protocol layer, from Stefan
Hajnoczi.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net:
VSOCK: set POLLOUT | POLLWRNORM for TCP_CLOSING
dccp: don't restart ccid2_hc_tx_rto_expire() if sk in closed state
net: vrf: Add support for sends to local broadcast address
r8169: fix memory corruption on retrieval of hardware statistics.
net: don't call update_pmtu unconditionally
net: tcp: close sock if net namespace is exiting
Now that we're upstream in Linux we've been able to make some
infrastructure changes so our port works a bit more like other ports.
Specifically:
* We now have a mailing list specific to the RISC-V Linux port, hosted
at lists.infreadead.org.
* We now have a kernel.org git tree where work on our port is
coordinated.
This patch changes the RISC-V maintainers entry to reflect these new
bits of infrastructure.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Both Geert and DaveJ reported that the recent futex commit:
c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
introduced a problem with setting OWNER_DEAD. We set the bit on an
uninitialized variable and then entirely optimize it away as a
dead-store.
Move the setting of the bit to where it is more useful.
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
Link: http://lkml.kernel.org/r/20180122103947.GD2228@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Lockdep noticed the following 3-way lockup race:
perf_trace_init()
#0 mutex_lock(&event_mutex)
perf_trace_event_init()
perf_trace_event_reg()
tp_event->class->reg() := tracepoint_probe_register
#1 mutex_lock(&tracepoints_mutex)
trace_point_add_func()
#2 static_key_enable()
#2 do_cpu_up()
perf_event_init_cpu()
#3 mutex_lock(&pmus_lock)
#4 mutex_lock(&ctx->mutex)
perf_ioctl()
#4 ctx = perf_event_ctx_lock()
_perf_iotcl()
ftrace_profile_set_filter()
#0 mutex_lock(&event_mutex)
Fudge it for now by noting that the tracepoint state does not depend
on the event <-> context relation. Ugly though :/
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull drm fixes from Dave Airlie:
"A fairly urgent nouveau regression fix for broken irqs across
suspend/resume came in. This was broken before but a patch in 4.15 has
made it much more obviously broken and now s/r fails a lot more often.
The fix removes freeing the irq across s/r which never should have
been done anyways.
Also two vc4 fixes for a NULL deference and some misrendering /
flickering on screen"
* tag 'drm-fixes-for-v4.15-rc10-2' of git://people.freedesktop.org/~airlied/linux:
drm/nouveau: Move irq setup/teardown to pci ctor/dtor
drm/vc4: Fix NULL pointer dereference in vc4_save_hang_state()
drm/vc4: Flush the caches before the bin jobs, as well.
select(2) with wfds but no rfds must return when the socket is shut down
by the peer. This way userspace notices socket activity and gets -EPIPE
from the next write(2).
Currently select(2) does not return for virtio-vsock when a SEND+RCV
shutdown packet is received. This is because vsock_poll() only sets
POLLOUT | POLLWRNORM for TCP_CLOSE, not the TCP_CLOSING state that the
socket is in when the shutdown is received.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>