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This commit adds self tests for early-boot use of RCU-tasks grace periods.
It tests all three variants (Rude, Tasks, and Tasks Trace) and covers
both synchronous (e.g., synchronize_rcu_tasks()) and asynchronous (e.g.,
call_rcu_tasks()) grace-period APIs.
Self-tests are run only in kernels built with CONFIG_PROVE_RCU=y.
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
[ paulmck: Handle CONFIG_PROVE_RCU=n and identify test cases' callbacks. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds a lockdep_assert_irqs_disabled() call to the
helper macros that release the rcu_node structure's ->lock, namely
to raw_spin_unlock_rcu_node(), raw_spin_unlock_irq_rcu_node() and
raw_spin_unlock_irqrestore_rcu_node(). The point of this is to help track
down a situation where lockdep appears to be insisting that interrupts
are enabled while holding an rcu_node structure's ->lock.
Link: https://lore.kernel.org/lkml/20201111133813.GA81547@elver.google.com/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds a number of lockdep_assert_irqs_disabled() calls
to rcu_sched_clock_irq() and a number of the functions that it calls.
The point of this is to help track down a situation where lockdep appears
to be insisting that interrupts are enabled within these functions, which
should only ever be invoked from the scheduling-clock interrupt handler.
Link: https://lore.kernel.org/lkml/20201111133813.GA81547@elver.google.com/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit removes an unnecessary #include.
Signed-off-by: Wang Qing <wangqing@vivo.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The try_invoke_on_locked_down_task() function currently requires
that interrupts be enabled, but it is called with interrupts
disabled from rcu_print_task_stall(), resulting in an "IRQs not
enabled as expected" diagnostic. This commit therefore updates
try_invoke_on_locked_down_task() to use raw_spin_lock_irqsave() instead
of raw_spin_lock_irq(), thus allowing use from either context.
Link: https://lore.kernel.org/lkml/000000000000903d5805ab908fc4@google.com/
Link: https://lore.kernel.org/lkml/20200928075729.GC2611@hirez.programming.kicks-ass.net/
Reported-by: syzbot+cb3b69ae80afd6535b0e@syzkaller.appspotmail.com
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Rewrite kcsan_prandom_u32_max() to not depend on code that might be
instrumented, removing any dependency on lib/random32.c. The rewrite
implements a simple linear congruential generator, that is sufficient
for our purposes (for udelay() and skip_watch counter randomness).
The initial motivation for this was to allow enabling KCSAN for
kernel/sched (remove KCSAN_SANITIZE := n from kernel/sched/Makefile),
with CONFIG_DEBUG_PREEMPT=y. Without this change, we could observe
recursion:
check_access() [via instrumentation]
kcsan_setup_watchpoint()
reset_kcsan_skip()
kcsan_prandom_u32_max()
get_cpu_var()
preempt_disable()
preempt_count_add() [in kernel/sched/core.c]
check_access() [via instrumentation]
Note, while this currently does not affect an unmodified kernel, it'd be
good to keep a KCSAN kernel working when KCSAN_SANITIZE := n is removed
from kernel/sched/Makefile to permit testing scheduler code with KCSAN
if desired.
Fixes: cd290ec24633 ("kcsan: Use tracing-safe version of prandom")
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Currently, RCU CPU stall warning messages will NMI whatever CPU looks
like it is blocking either the current grace period or the grace-period
kthread. This can produce confusing output if the target CPU is offline.
This commit therefore checks for offline CPUs.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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When the RCU CPU stall-warning code detects that the RCU grace-period
kthread is being starved, it dumps that kthread's stack. This can
sometimes be useful, but it is also useful to know what is running on the
CPU that this kthread is attempting to run on. This commit therefore
adds a stack trace of this CPU in order to help track down whatever it
is that might be preventing RCU's grace-period kthread from running.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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There is a rather obtuse string that can be printed as part of an
expedited RCU CPU stall-warning message that starts with "blocking
rcu_node structures". Under normal conditions, most of this message
is just repeating the list of CPUs blocking the current expedited grace
period, but in a manner that is rather difficult to read. This commit
therefore marks this message as "(internal RCU debug)" in an effort to
give people the option of avoiding wasting time attempting to extract
nonexistent additional meaning from this portion of the message.
Reported-by: Jonathan Lemon <bsd@fb.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds the desired CPU, the actual CPU, and nr_cpu_ids to
the wrong-CPU warning in scftorture_invoker(), the better to help with
debugging.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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RCU guarantees that anything seen by a given reader will also be seen
after any grace period that must wait on that reader. This is very likely
to hold based on inspection, but the advantage of having rcutorture do
the inspecting is that rcutorture doesn't mind inspecting frequently
and often.
This commit therefore adds code to test RCU's global memory ordering.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds reader-side testing of the polling grace-period API.
This testing verifies that a cookie obtained in an SRCU read-side critical
section does not get a true return from poll_state_synchronize_srcu()
within that same critical section.
Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds writer-side testing of the polling grace-period API.
One test verifies that the polling API sees a grace period caused by
some other mechanism. Another test verifies that using the polling API
to wait for a grace period does not result in too-short grace periods.
A third test verifies that the polling API does not report
completion within a read-side critical section. A fourth and final
test verifies that the polling API does report completion given an
intervening grace period.
Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The new get_state_synchronize_srcu(), start_poll_synchronize_srcu() and
poll_state_synchronize_srcu() functions need to be tested, and so this
commit prepares by renaming the rcu_torture_ops field ->get_state to
->get_gp_state in order to be consistent with the upcoming ->start_gp_poll
and ->poll_gp_state fields.
Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds to the poll_state_synchronize_srcu() header comment
describing the issues surrounding SRCU cookie overflow/wrap for the
different kernel configurations.
Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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There is a need for a polling interface for SRCU grace
periods, so this commit supplies get_state_synchronize_srcu(),
start_poll_synchronize_srcu(), and poll_state_synchronize_srcu() for this
purpose. The first can be used if future grace periods are inevitable
(perhaps due to a later call_srcu() invocation), the second if future
grace periods might not otherwise happen, and the third to check if a
grace period has elapsed since the corresponding call to either of the
first two.
As with get_state_synchronize_rcu() and cond_synchronize_rcu(),
the return value from either get_state_synchronize_srcu() or
start_poll_synchronize_srcu() must be passed in to a later call to
poll_state_synchronize_srcu().
Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
[ paulmck: Add EXPORT_SYMBOL_GPL() per kernel test robot feedback. ]
[ paulmck: Apply feedback from Neeraj Upadhyay. ]
Link: https://lore.kernel.org/lkml/20201117004017.GA7444@paulmck-ThinkPad-P72/
Reviewed-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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There is a need for a polling interface for SRCU grace
periods, so this commit supplies get_state_synchronize_srcu(),
start_poll_synchronize_srcu(), and poll_state_synchronize_srcu() for this
purpose. The first can be used if future grace periods are inevitable
(perhaps due to a later call_srcu() invocation), the second if future
grace periods might not otherwise happen, and the third to check if a
grace period has elapsed since the corresponding call to either of the
first two.
As with get_state_synchronize_rcu() and cond_synchronize_rcu(),
the return value from either get_state_synchronize_srcu() or
start_poll_synchronize_srcu() must be passed in to a later call to
poll_state_synchronize_srcu().
Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
[ paulmck: Add EXPORT_SYMBOL_GPL() per kernel test robot feedback. ]
[ paulmck: Apply feedback from Neeraj Upadhyay. ]
Link: https://lore.kernel.org/lkml/20201117004017.GA7444@paulmck-ThinkPad-P72/
Reviewed-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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There is a need for a polling interface for SRCU grace periods.
This polling needs to initiate an SRCU grace period without having
to queue (and manage) a callback. This commit therefore splits the
Tree SRCU __call_srcu() function into callback-initialization and
queuing/start-grace-period portions, with the latter in a new function
named srcu_gp_start_if_needed(). This function may be passed a NULL
callback pointer, in which case it will refrain from queuing anything.
Why have the new function mess with queuing? Locking considerations,
of course!
Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Reviewed-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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There is a need for a polling interface for SRCU grace periods.
This polling needs to initiate an SRCU grace period without
having to queue (and manage) a callback. This commit therefore
splits the Tiny SRCU call_srcu() function into callback-queuing and
start-grace-period portions, with the latter in a new function named
srcu_gp_start_if_needed().
Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Reviewed-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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There is a need for a polling interface for SRCU grace periods. This
polling needs to distinguish between an SRCU instance being idle on the
one hand or in the middle of a grace period on the other. This commit
therefore converts the Tiny SRCU srcu_struct structure's srcu_idx from
a defacto boolean to a free-running counter, using the bottom bit to
indicate that a grace period is in progress. The second-from-bottom
bit is thus used as the index returned by srcu_read_lock().
Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
[ paulmck: Fix ->srcu_lock_nesting[] indexing per Neeraj Upadhyay. ]
Reviewed-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Expedited RCU grace periods send IPIs to all non-idle CPUs, and thus can
disrupt time-critical code in real-time applications. However, there
is a portion of boot-time processing (presumably before any real-time
applications have started) where expedited RCU grace periods are the only
option. And so it is that experience with the -rt patchset indicates that
PREEMPT_RT systems should always set the rcupdate.rcu_normal_after_boot
kernel boot parameter.
This commit therefore makes the post-boot application environment safe
for real-time applications by making PREEMPT_RT systems disable the
rcupdate.rcu_normal_after_boot kernel boot parameter and acting as
if this parameter had been set. This means that post-boot calls to
synchronize_rcu_expedited() will be treated as if they were instead
calls to synchronize_rcu(), thus preventing the IPIs, and thus avoiding
disrupting real-time applications.
Suggested-by: Luiz Capitulino <lcapitulino@redhat.com>
Acked-by: Paul E. McKenney <paulmck@linux.ibm.com>
Signed-off-by: Julia Cartwright <julia@ni.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
[ paulmck: Update kernel-parameters.txt accordingly. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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PREEMPT_RT systems have long used the rcutree.use_softirq kernel
boot parameter to avoid use of RCU_SOFTIRQ handlers, which can disrupt
real-time applications by invoking callbacks during return from interrupts
that arrived while executing time-critical code. This kernel boot
parameter instead runs RCU core processing in an 'rcuc' kthread, thus
allowing the scheduler to do its job of avoiding disrupting time-critical
code.
This commit therefore disables the rcutree.use_softirq kernel boot
parameter on PREEMPT_RT systems, thus forcing such systems to do RCU
core processing in 'rcuc' kthreads. This approach has long been in
use by users of the -rt patchset, and there have been no complaints.
There is therefore no way for the system administrator to override this
choice, at least without modifying and rebuilding the kernel.
Signed-off-by: Scott Wood <swood@redhat.com>
[bigeasy: Reword commit message]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
[ paulmck: Update kernel-parameters.txt accordingly. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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On PREEMPT_RT kernels, RCU callbacks are deferred to the `rcuc' kthread.
This can stall RCU grace periods due to lengthy preemption not only of RCU
readers but also of 'rcuc' kthreads, either of which prevent grace periods
from completing, which can in turn result in OOM. Because PREEMPT_RT
kernels have more kthreads that can block grace periods, it is more
important for such kernels to enable RCU_BOOST.
This commit therefore makes RCU_BOOST the default on PREEMPT_RT.
RCU_BOOST can still be manually disabled if need be.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds a call to kasan_record_aux_stack() in kvfree_call_rcu()
in order to record the call stack of the code that caused the object
to be freed. Please note that this function does not update the
allocated/freed state, which is important because RCU readers might
still be referencing this object.
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Zqiang <qiang.zhang@windriver.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The rcu_do_batch() function extracts the ready-to-invoke callbacks
from the rcu_segcblist located in the ->cblist field of the current
CPU's rcu_data structure. These callbacks are first moved to a local
(unsegmented) rcu_cblist. The rcu_do_batch() function then uses this
rcu_cblist's ->len field to count how many CBs it has invoked, but it
does so by counting that field down from zero. Finally, this function
negates the value in this ->len field (resulting in a positive number)
and subtracts the result from the ->len field of the current CPU's
->cblist field.
Except that it is sometimes necessary for rcu_do_batch() to stop invoking
callbacks mid-stream, despite there being more ready to invoke, for
example, if a high-priority task wakes up. In this case the remaining
not-yet-invoked callbacks are requeued back onto the CPU's ->cblist,
but remain in the ready-to-invoke segment of that list. As above, the
negative of the local rcu_cblist's ->len field is still subtracted from
the ->len field of the current CPU's ->cblist field.
The design of counting down from 0 is confusing and error-prone, plus
use of a positive count will make it easier to provide a uniform and
consistent API to deal with the per-segment counts that are added
later in this series. For example, rcu_segcblist_extract_done_cbs()
can unconditionally populate the resulting unsegmented list's ->len
field during extraction.
This commit therefore explicitly counts how many callbacks were executed
in rcu_do_batch() itself, counting up from zero, and then uses that
to update the per-CPU segcb list's ->len field, without relying on the
downcounting of rcl->len from zero.
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu
Pull RCU fix from Paul McKenney:
"This is a fix for a regression in the v5.10 merge window, but it was
reported quite late in the v5.10 process, plus generating and testing
the fix took some time.
The regression is due to commit 36dadef23fcc ("kprobes: Init kprobes
in early_initcall") which on powerpc can use RCU Tasks before
initialization, resulting in boot failures.
The fix is straightforward, simply moving initialization of RCU Tasks
before the early_initcall()s. The fix has been exposed to -next and
kbuild test robot testing, and has been tested by the PowerPC guys"
* 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
rcu-tasks: Move RCU-tasks initialization to before early_initcall()
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Latest bpf tree has a bug for bpf_iter selftest:
$ ./test_progs -n 4/25
test_bpf_sk_storage_get:PASS:bpf_iter_bpf_sk_storage_helpers__open_and_load 0 nsec
test_bpf_sk_storage_get:PASS:socket 0 nsec
...
do_dummy_read:PASS:read 0 nsec
test_bpf_sk_storage_get:FAIL:bpf_map_lookup_elem map value wasn't set correctly
(expected 1792, got -1, err=0)
#4/25 bpf_sk_storage_get:FAIL
#4 bpf_iter:FAIL
Summary: 0/0 PASSED, 0 SKIPPED, 2 FAILED
When doing merge conflict resolution, Commit 4bfc4714849d missed to
save curr_task to seq_file private data. The task pointer in seq_file
private data is passed to bpf program. This caused NULL-pointer task
passed to bpf program which will immediately return upon checking
whether task pointer is NULL.
This patch added back the assignment of curr_task to seq_file private
data and fixed the issue.
Fixes: 4bfc4714849d ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20201231052418.577024-1-yhs@fb.com
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Pull io_uring fixes from Jens Axboe:
"A few fixes that should go into 5.11, all marked for stable as well:
- Fix issue around identity COW'ing and users that share a ring
across processes
- Fix a hang associated with unregistering fixed files (Pavel)
- Move the 'process is exiting' cancelation a bit earlier, so
task_works aren't affected by it (Pavel)"
* tag 'io_uring-5.11-2021-01-01' of git://git.kernel.dk/linux-block:
kernel/io_uring: cancel io_uring before task works
io_uring: fix io_sqe_files_unregister() hangs
io_uring: add a helper for setting a ref node
io_uring: don't assume mm is constant across submits
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For cancelling io_uring requests it needs either to be able to run
currently enqueued task_works or having it shut down by that moment.
Otherwise io_uring_cancel_files() may be waiting for requests that won't
ever complete.
Go with the first way and do cancellations before setting PF_EXITING and
so before putting the task_work infrastructure into a transition state
where task_work_run() would better not be called.
Cc: stable@vger.kernel.org # 5.5+
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Daniel Borkmann says:
====================
pull-request: bpf 2020-12-28
The following pull-request contains BPF updates for your *net* tree.
There is a small merge conflict between bpf tree commit 69ca310f3416
("bpf: Save correct stopping point in file seq iteration") and net tree
commit 66ed594409a1 ("bpf/task_iter: In task_file_seq_get_next use
task_lookup_next_fd_rcu"). The get_files_struct() does not exist anymore
in net, so take the hunk in HEAD and add the `info->tid = curr_tid` to
the error path:
[...]
curr_task = task_seq_get_next(ns, &curr_tid, true);
if (!curr_task) {
info->task = NULL;
info->tid = curr_tid;
return NULL;
}
/* set info->task and info->tid */
[...]
We've added 10 non-merge commits during the last 9 day(s) which contain
a total of 11 files changed, 75 insertions(+), 20 deletions(-).
The main changes are:
1) Various AF_XDP fixes such as fill/completion ring leak on failed bind and
fixing a race in skb mode's backpressure mechanism, from Magnus Karlsson.
2) Fix latency spikes on lockdep enabled kernels by adding a rescheduling
point to BPF hashtab initialization, from Eric Dumazet.
3) Fix a splat in task iterator by saving the correct stopping point in the
seq file iteration, from Jonathan Lemon.
4) Fix BPF maps selftest by adding retries in case hashtab returns EBUSY
errors on update/deletes, from Andrii Nakryiko.
5) Fix BPF selftest error reporting to something more user friendly if the
vmlinux BTF cannot be found, from Kamal Mostafa.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
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Pull workqueue update from Tejun Heo:
"The same as the cgroup tree - one commit which was scheduled for the
5.11 merge window.
All the commit does is avoding spurious worker wakeups from workqueue
allocation / config change path to help cpuisol use cases"
* 'for-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: Kick a worker based on the actual activation of delayed works
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git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
"These three patches were scheduled for the merge window but I forgot
to send them out. Sorry about that.
None of them are significant and they fit well in a fix pull request
too - two are cosmetic and one fixes a memory leak in the mount option
parsing path"
* 'for-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: Fix memory leak when parsing multiple source parameters
cgroup/cgroup.c: replace 'of->kn->priv' with of_cft()
kernel: cgroup: Mundane spelling fixes throughout the file
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fixes from Ingo Molnar:
"Misc fixes/updates:
- Fix static keys usage in module __init sections
- Add separate MAINTAINERS entry for static branches/calls
- Fix lockdep splat with CONFIG_PREEMPTIRQ_EVENTS=y tracing"
* tag 'locking-urgent-2020-12-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
softirq: Avoid bad tracing / lockdep interaction
jump_label/static_call: Add MAINTAINERS
jump_label: Fix usage in module __init
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fixes from Ingo Molnar:
"Update/fix two CPU sanity checks in the hotplug and the boot code, and
fix a typo in the Kconfig help text.
[ Context: the first two commits are the result of an ongoing
annotation+review work of (intentional) tick_do_timer_cpu() data
races reported by KCSAN, but the annotations aren't fully cooked
yet ]"
* tag 'timers-urgent-2020-12-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
timekeeping: Fix spelling mistake in Kconfig "fullfill" -> "fulfill"
tick/sched: Remove bogus boot "safety" check
tick: Remove pointless cpu valid check in hotplug code
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fix from Ingo Molnar:
"Fix a context switch performance regression"
* tag 'sched-urgent-2020-12-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched: Optimize finish_lock_switch()
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Commit 64a1b95bb9fe ("genirq: Restrict export of irq_to_desc()") removed
the export of irq_to_desc() unless powerpc KVM is being built, because
there is still a use of irq_to_desc() in modular code there.
However it used:
#ifdef CONFIG_KVM_BOOK3S_64_HV
Which doesn't work when that symbol is =m, leading to a build failure:
ERROR: modpost: "irq_to_desc" [arch/powerpc/kvm/kvm-hv.ko] undefined!
Fix it by checking for the definedness of the correct symbol which is
CONFIG_KVM_BOOK3S_64_HV_MODULE.
Fixes: 64a1b95bb9fe ("genirq: Restrict export of irq_to_desc()")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull irq updates from Thomas Gleixner:
"This is the second attempt after the first one failed miserably and
got zapped to unblock the rest of the interrupt related patches.
A treewide cleanup of interrupt descriptor (ab)use with all sorts of
racy accesses, inefficient and disfunctional code. The goal is to
remove the export of irq_to_desc() to prevent these things from
creeping up again"
* tag 'irq-core-2020-12-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (30 commits)
genirq: Restrict export of irq_to_desc()
xen/events: Implement irq distribution
xen/events: Reduce irq_info:: Spurious_cnt storage size
xen/events: Only force affinity mask for percpu interrupts
xen/events: Use immediate affinity setting
xen/events: Remove disfunct affinity spreading
xen/events: Remove unused bind_evtchn_to_irq_lateeoi()
net/mlx5: Use effective interrupt affinity
net/mlx5: Replace irq_to_desc() abuse
net/mlx4: Use effective interrupt affinity
net/mlx4: Replace irq_to_desc() abuse
PCI: mobiveil: Use irq_data_get_irq_chip_data()
PCI: xilinx-nwl: Use irq_data_get_irq_chip_data()
NTB/msi: Use irq_has_action()
mfd: ab8500-debugfs: Remove the racy fiddling with irq_desc
pinctrl: nomadik: Use irq_has_action()
drm/i915/pmu: Replace open coded kstat_irqs() copy
drm/i915/lpe_audio: Remove pointless irq_to_desc() usage
s390/irq: Use irq_desc_kstat_cpu() in show_msi_interrupt()
parisc/irq: Use irq_desc_kstat_cpu() in show_interrupts()
...
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Instead of directly comparing task->tgid and task->pid, use the
thread_group_leader() helper. This helps with readability, and
there should be no functional change.
Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201218185032.2464558-3-jonathan.lemon@gmail.com
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On some systems, some variant of the following splat is
repeatedly seen. The common factor in all traces seems
to be the entry point to task_file_seq_next(). With the
patch, all warnings go away.
rcu: INFO: rcu_sched self-detected stall on CPU
rcu: \x0926-....: (20992 ticks this GP) idle=d7e/1/0x4000000000000002 softirq=81556231/81556231 fqs=4876
\x09(t=21033 jiffies g=159148529 q=223125)
NMI backtrace for cpu 26
CPU: 26 PID: 2015853 Comm: bpftool Kdump: loaded Not tainted 5.6.13-0_fbk4_3876_gd8d1f9bf80bb #1
Hardware name: Quanta Twin Lakes MP/Twin Lakes Passive MP, BIOS F09_3A12 10/08/2018
Call Trace:
<IRQ>
dump_stack+0x50/0x70
nmi_cpu_backtrace.cold.6+0x13/0x50
? lapic_can_unplug_cpu.cold.30+0x40/0x40
nmi_trigger_cpumask_backtrace+0xba/0xca
rcu_dump_cpu_stacks+0x99/0xc7
rcu_sched_clock_irq.cold.90+0x1b4/0x3aa
? tick_sched_do_timer+0x60/0x60
update_process_times+0x24/0x50
tick_sched_timer+0x37/0x70
__hrtimer_run_queues+0xfe/0x270
hrtimer_interrupt+0xf4/0x210
smp_apic_timer_interrupt+0x5e/0x120
apic_timer_interrupt+0xf/0x20
</IRQ>
RIP: 0010:get_pid_task+0x38/0x80
Code: 89 f6 48 8d 44 f7 08 48 8b 00 48 85 c0 74 2b 48 83 c6 55 48 c1 e6 04 48 29 f0 74 19 48 8d 78 20 ba 01 00 00 00 f0 0f c1 50 20 <85> d2 74 27 78 11 83 c2 01 78 0c 48 83 c4 08 c3 31 c0 48 83 c4 08
RSP: 0018:ffffc9000d293dc8 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13
RAX: ffff888637c05600 RBX: ffffc9000d293e0c RCX: 0000000000000000
RDX: 0000000000000001 RSI: 0000000000000550 RDI: ffff888637c05620
RBP: ffffffff8284eb80 R08: ffff88831341d300 R09: ffff88822ffd8248
R10: ffff88822ffd82d0 R11: 00000000003a93c0 R12: 0000000000000001
R13: 00000000ffffffff R14: ffff88831341d300 R15: 0000000000000000
? find_ge_pid+0x1b/0x20
task_seq_get_next+0x52/0xc0
task_file_seq_get_next+0x159/0x220
task_file_seq_next+0x4f/0xa0
bpf_seq_read+0x159/0x390
vfs_read+0x8a/0x140
ksys_read+0x59/0xd0
do_syscall_64+0x42/0x110
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f95ae73e76e
Code: Bad RIP value.
RSP: 002b:00007ffc02c1dbf8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 000000000170faa0 RCX: 00007f95ae73e76e
RDX: 0000000000001000 RSI: 00007ffc02c1dc30 RDI: 0000000000000007
RBP: 00007ffc02c1ec70 R08: 0000000000000005 R09: 0000000000000006
R10: fffffffffffff20b R11: 0000000000000246 R12: 00000000019112a0
R13: 0000000000000000 R14: 0000000000000007 R15: 00000000004283c0
If unable to obtain the file structure for the current task,
proceed to the next task number after the one returned from
task_seq_get_next(), instead of the next task number from the
original iterator.
Also, save the stopping task number from task_seq_get_next()
on failure in case of restarts.
Fixes: eaaacd23910f ("bpf: Add task and task/file iterator targets")
Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201218185032.2464558-2-jonathan.lemon@gmail.com
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git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull more power management updates from Rafael Wysocki:
"These update the CPPC cpufreq driver and intel_pstate (which involves
updating the cpufreq core and the schedutil governor) and make
janitorial changes in the ACPI code handling processor objects.
Specifics:
- Rework the passive-mode "fast switch" path in the intel_pstate
driver to allow it receive the minimum (required) and target
(desired) performance information from the schedutil governor so as
to avoid running some workloads too fast (Rafael Wysocki).
- Make the intel_pstate driver allow the policy max limit to be
increased after the guaranteed performance value for the given CPU
has increased (Rafael Wysocki).
- Clean up the handling of CPU coordination types in the CPPC cpufreq
driver and make it export frequency domains information to user
space via sysfs (Ionela Voinescu).
- Fix the ACPI code handling processor objects to use a correct
coordination type when it fails to map frequency domains and drop a
redundant CPU map initialization from it (Ionela Voinescu, Punit
Agrawal)"
* tag 'pm-5.11-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
cpufreq: intel_pstate: Use most recent guaranteed performance values
cpufreq: intel_pstate: Implement the ->adjust_perf() callback
cpufreq: Add special-purpose fast-switching callback for drivers
cpufreq: schedutil: Add util to struct sg_cpu
cppc_cpufreq: replace per-cpu data array with a list
cppc_cpufreq: expose information on frequency domains
cppc_cpufreq: clarify support for coordination types
cppc_cpufreq: use policy->cpu as driver of frequency setting
ACPI: processor: fix NONE coordination for domain mapping failure
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Merge KASAN updates from Andrew Morton.
This adds a new hardware tag-based mode to KASAN. The new mode is
similar to the existing software tag-based KASAN, but relies on arm64
Memory Tagging Extension (MTE) to perform memory and pointer tagging
(instead of shadow memory and compiler instrumentation).
By Andrey Konovalov and Vincenzo Frascino.
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (60 commits)
kasan: update documentation
kasan, mm: allow cache merging with no metadata
kasan: sanitize objects when metadata doesn't fit
kasan: clarify comment in __kasan_kfree_large
kasan: simplify assign_tag and set_tag calls
kasan: don't round_up too much
kasan, mm: rename kasan_poison_kfree
kasan, mm: check kasan_enabled in annotations
kasan: add and integrate kasan boot parameters
kasan: inline (un)poison_range and check_invalid_free
kasan: open-code kasan_unpoison_slab
kasan: inline random_tag for HW_TAGS
kasan: inline kasan_reset_tag for tag-based modes
kasan: remove __kasan_unpoison_stack
kasan: allow VMAP_STACK for HW_TAGS mode
kasan, arm64: unpoison stack only with CONFIG_KASAN_STACK
kasan: introduce set_alloc_info
kasan: rename get_alloc/free_info
kasan: simplify quarantine_put call site
kselftest/arm64: check GCR_EL1 after context switch
...
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Pull dma-mapping updates from Christoph Hellwig:
- support for a partial IOMMU bypass (Alexey Kardashevskiy)
- add a DMA API benchmark (Barry Song)
- misc fixes (Tiezhu Yang, tangjianqiang)
* tag 'dma-mapping-5.11' of git://git.infradead.org/users/hch/dma-mapping:
selftests/dma: add test application for DMA_MAP_BENCHMARK
dma-mapping: add benchmark support for streaming DMA APIs
dma-contiguous: fix a typo error in a comment
dma-pool: no need to check return value of debugfs_create functions
powerpc/dma: Fallback to dma_ops when persistent memory present
dma-mapping: Allow mixing bypass and mapped DMA operation
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This is a preparatory commit for the upcoming addition of a new hardware
tag-based (MTE-based) KASAN mode.
The new mode won't be using shadow memory. Rename external annotation
kasan_unpoison_shadow() to kasan_unpoison_range(), and introduce internal
functions (un)poison_range() (without kasan_ prefix).
Co-developed-by: Marco Elver <elver@google.com>
Link: https://lkml.kernel.org/r/fccdcaa13dc6b2211bf363d6c6d499279a54fe3a.1606161801.git.andreyknvl@google.com
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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* pm-cpufreq:
cpufreq: intel_pstate: Use most recent guaranteed performance values
cpufreq: intel_pstate: Implement the ->adjust_perf() callback
cpufreq: Add special-purpose fast-switching callback for drivers
cpufreq: schedutil: Add util to struct sg_cpu
cppc_cpufreq: replace per-cpu data array with a list
cppc_cpufreq: expose information on frequency domains
cppc_cpufreq: clarify support for coordination types
cppc_cpufreq: use policy->cpu as driver of frequency setting
ACPI: processor: fix NONE coordination for domain mapping failure
ACPI: processor: Drop duplicate setting of shared_cpu_map
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We noticed that with a LOCKDEP enabled kernel,
allocating a hash table with 65536 buckets would
use more than 60ms.
htab_init_buckets() runs from process context,
it is safe to schedule to avoid latency spikes.
Fixes: c50eb518e262 ("bpf: Use separate lockdep class for each hashtab")
Reported-by: John Sperbeck <jsperbeck@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20201221192506.707584-1-eric.dumazet@gmail.com
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Pull KVM updates from Paolo Bonzini:
"Much x86 work was pushed out to 5.12, but ARM more than made up for it.
ARM:
- PSCI relay at EL2 when "protected KVM" is enabled
- New exception injection code
- Simplification of AArch32 system register handling
- Fix PMU accesses when no PMU is enabled
- Expose CSV3 on non-Meltdown hosts
- Cache hierarchy discovery fixes
- PV steal-time cleanups
- Allow function pointers at EL2
- Various host EL2 entry cleanups
- Simplification of the EL2 vector allocation
s390:
- memcg accouting for s390 specific parts of kvm and gmap
- selftest for diag318
- new kvm_stat for when async_pf falls back to sync
x86:
- Tracepoints for the new pagetable code from 5.10
- Catch VFIO and KVM irqfd events before userspace
- Reporting dirty pages to userspace with a ring buffer
- SEV-ES host support
- Nested VMX support for wait-for-SIPI activity state
- New feature flag (AVX512 FP16)
- New system ioctl to report Hyper-V-compatible paravirtualization features
Generic:
- Selftest improvements"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (171 commits)
KVM: SVM: fix 32-bit compilation
KVM: SVM: Add AP_JUMP_TABLE support in prep for AP booting
KVM: SVM: Provide support to launch and run an SEV-ES guest
KVM: SVM: Provide an updated VMRUN invocation for SEV-ES guests
KVM: SVM: Provide support for SEV-ES vCPU loading
KVM: SVM: Provide support for SEV-ES vCPU creation/loading
KVM: SVM: Update ASID allocation to support SEV-ES guests
KVM: SVM: Set the encryption mask for the SVM host save area
KVM: SVM: Add NMI support for an SEV-ES guest
KVM: SVM: Guest FPU state save/restore not needed for SEV-ES guest
KVM: SVM: Do not report support for SMM for an SEV-ES guest
KVM: x86: Update __get_sregs() / __set_sregs() to support SEV-ES
KVM: SVM: Add support for CR8 write traps for an SEV-ES guest
KVM: SVM: Add support for CR4 write traps for an SEV-ES guest
KVM: SVM: Add support for CR0 write traps for an SEV-ES guest
KVM: SVM: Add support for EFER write traps for an SEV-ES guest
KVM: SVM: Support string IO operations for an SEV-ES guest
KVM: SVM: Support MMIO for an SEV-ES guest
KVM: SVM: Create trace events for VMGEXIT MSR protocol processing
KVM: SVM: Create trace events for VMGEXIT processing
...
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Split off from prev patch in the series that implements the syscall.
Link: https://lkml.kernel.org/r/20201121144401.3727659-4-willemdebruijn.kernel@gmail.com
Signed-off-by: Willem de Bruijn <willemb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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There is a spelling mistake in the Kconfig help text. Fix it.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20201217171705.57586-1-colin.king@canonical.com
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Since commit 5fe71d271df8 ("irqchip/gic-v3-its: Tag ITS device as shared if
allocating for a proxy device"), some of the devices are wrongly marked as
"shared" by the ITS driver on systems equipped with the ITS(es). The
problem is that the @info->flags may not be initialized anywhere and we end
up looking at random bits on the stack. That's obviously not good.
We can perform the initialization in the IRQ core layer before calling
msi_domain_prepare_irqs(), which is neat enough.
Fixes: 5fe71d271df8 ("irqchip/gic-v3-its: Tag ITS device as shared if allocating for a proxy device")
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201218060039.1770-1-yuzenghui@huawei.com
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Similar to commit:
1a63dcd8765b ("softirq: Reorder trace_softirqs_on to prevent lockdep splat")
__local_bh_enable_ip() can also call into tracing with inconsistent
state. Unlike that commit we don't need to bother about the tracepoint
because 'cnt-1' never matches preempt_count() (by construction).
Reported-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lkml.kernel.org/r/20201218154519.GW3092@hirez.programming.kicks-ass.net
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