From: "Paul E. McKenney"
After the sync() in __list_splice_init_rcu(), there should be no
readers traversing the old list. This commit therefore enlists the
help of KCSAN to verify this condition via a pair of calls to
ASSERT_EXCLUSIVE_ACCESS().
Signed-off-by: Paul E. McKenney
Cc: Marco Elver
From: Qian Cai
cpa_4k_install could be accessed concurrently as noticed by KCSAN,
read to 0xaa59a000 of 8 bytes by interrupt on cpu 7:
cpa_inc_4k_install arch/x86/mm/pat/set_memory.c:131 [inline]
__change_page_attr+0x10cf/0x1840 arch/x86/mm/pat/set_memory.c:1514
__change_page_attr_set_cl
From: Marco Elver
Rename 'test.c' to 'selftest.c' to better reflect its purpose (Kconfig
variable and code inside already match this). This is to avoid confusion
with the test suite module in 'kcsan-test.c'.
No functional change.
Signed-off-by: Marco Elver
Signed-off-by: Paul E. McKenney
---
From: "Paul E. McKenney"
KCSAN is now in mainline, so this commit removes the stubs for the
data_race(), ASSERT_EXCLUSIVE_WRITER(), and ASSERT_EXCLUSIVE_ACCESS()
macros.
Signed-off-by: Paul E. McKenney
---
kernel/rcu/rcutorture.c | 13 -
1 file changed, 13 deletions(-)
diff --git
From: Akira Yokosawa
The name of litmus test doesn't match the one described below.
Fix the name of litmus test.
Acked-by: Andrea Parri
Acked-by: Joel Fernandes (Google)
Signed-off-by: Akira Yokosawa
Signed-off-by: Paul E. McKenney
---
tools/memory-model/Documentation/recipes.txt | 2 +-
1
From: Marco Elver
The definition of "conflict" should not include the type of access nor
whether the accesses are concurrent or not, which this patch addresses.
The definition of "data race" remains unchanged.
The definition of "conflict" as we know it and is cited by various
papers on memory co
From: Boqun Feng
Although we have atomic_t.txt and its friends to describe the semantics
of atomic APIs and lib/atomic64_test.c for build testing and testing in
UP mode, the tests for our atomic APIs in real SMP mode are still
missing. Since now we have the LKMM tool in kernel and litmus tests ca
From: Mauro Carvalho Chehab
As we moved those files to core-api, fix references to point
to their newer locations.
Signed-off-by: Mauro Carvalho Chehab
Signed-off-by: Paul E. McKenney
---
Documentation/memory-barriers.txt | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git
From: "Joel Fernandes (Google)"
This adds an example for the important RCU grace period guarantee, which
shows an RCU reader can never span a grace period.
Acked-by: Andrea Parri
Signed-off-by: Joel Fernandes (Google)
Signed-off-by: Paul E. McKenney
---
.../litmus-tests/rcu/RCU+sync+free.lit
From: Akira Yokosawa
Where Documentation/litmus-tests/README lists RCU litmus tests,
Documentation/litmus-tests/atomic/README lists atomic litmus tests.
For symmetry, merge the latter into former, with some context
adjustment in the introduction.
Acked-by: Andrea Parri
Acked-by: Joel Fernandes
From: "Joel Fernandes (Google)"
This adds an example for the important RCU grace period guarantee, which
shows an RCU reader can never span a grace period.
Acked-by: Andrea Parri
Signed-off-by: Joel Fernandes (Google)
Signed-off-by: Paul E. McKenney
---
Documentation/litmus-tests/README
From: Akira Yokosawa
klitmus7 is independent of the memory model but depends on the
build-target kernel release.
It occasionally lost compatibility due to kernel API changes [1, 2, 3].
It was remedied in a backwards-compatible manner respectively [4, 5, 6].
Reflect this fact in README.
[1]: b89
From: Boqun Feng
We already use a litmus test in atomic_t.txt to describe atomic RMW +
smp_mb__after_atomic() is stronger than acquire (both the read and the
write parts are ordered). So make it a litmus test in atomic-tests
directory, so that people can access the litmus easily.
Additionally, c
From: Boqun Feng
According to Luc, atomic_add_unless() is directly provided by herd7,
therefore it can be used in litmus tests. So change the limitation
section in README to unlimit the use of atomic_add_unless().
Cc: Luc Maranget
Acked-by: Andrea Parri
Reviewed-by: Joel Fernandes (Google)
Si
t;
Linux Weekly News. https://lwn.net/Articles/720550/
+o Jade Alglave, Luc Maranget, Paul E. McKenney, Andrea Parri, and
+ Alan Stern. 2017-2019. "A Formal Model of Linux-Kernel Memory
+ Ordering" (backup material for the LWN articles)
+
https://m
From: "Joel Fernandes (Google)"
This commit cites a pertinent RCU-related litmus test.
Co-developed-by: Joel Fernandes (Google)
Co-developed-by: Akira Yokosawa
[Alan: grammar nit]
[ paulmck: Update commit log and title per Akira feedback. ]
Suggested-by: Alan Stern
Signed-of
From: Boqun Feng
We already use a litmus test in atomic_t.txt to describe the behavior of
an atomic_set() with the an atomic RMW, so add it into atomic-tests
directory to make it easily accessible for anyone who cares about the
semantics of our atomic APIs.
Besides currently the litmus test "ato
From: "Joel Fernandes (Google)"
This commit adds Joel Fernandes as official LKMM reviewer.
Acked-by: Boqun Feng
Acked-by: Andrea Parri
Signed-off-by: Joel Fernandes (Google)
[ paulmck: Apply Joe Perches alphabetization feedback. ]
Signed-off-by: Paul E. McKenney
---
MAINTAINERS
From: Thomas Gleixner
CONFIG_PREEMPT_COUNT is now unconditionally enabled and will be
removed. Cleanup the leftovers before doing so.
Signed-off-by: Thomas Gleixner
Cc: "Paul E. McKenney"
Cc: Josh Triplett
Cc: Steven Rostedt
Cc: Mathieu Desnoyers
Cc: Lai Jiangshan
Cc: Shuah Khan
Cc: r...@
From: "Uladzislau Rezki (Sony)"
The current memory-allocation interface poses the following challenges:
a) In kernels built with CONFIG_PROVE_RAW_LOCK_NESTING, lockdep
complains ("BUG: Invalid wait context"). This complaint is due
to the memory allocator acquiring non-raw s
From: Thomas Gleixner
The handling of preempt_count() is inconsistent across kernel
configurations. On kernels which have PREEMPT_COUNT=n
preempt_disable/enable() and the lock/unlock functions are not affecting
the preempt count, only local_bh_disable/enable() and _bh variants of
locking, soft in
From: Thomas Gleixner
CONFIG_PREEMPT_COUNT is now unconditionally enabled and will be
removed. Cleanup the leftovers before doing so.
Signed-off-by: Thomas Gleixner
Cc: Ingo Molnar
Cc: Peter Zijlstra
Cc: Juri Lelli
Cc: Vincent Guittot
Cc: Dietmar Eggemann
Cc: Steven Rostedt
Cc: Ben Segall
From: Thomas Gleixner
CONFIG_PREEMPT_COUNT is now unconditionally enabled and will be
removed. Cleanup the leftovers before doing so.
Signed-off-by: Thomas Gleixner
Cc: Russell King
Cc: linux-arm-ker...@lists.infradead.org
Signed-off-by: Paul E. McKenney
---
arch/arm/include/asm/assembler.h
From: Thomas Gleixner
CONFIG_PREEMPT_COUNT is now unconditionally enabled and will be
removed. Cleanup the leftovers before doing so.
Signed-off-by: Thomas Gleixner
Cc: Andrew Morton
Cc: linux...@kvack.org
[ paulmck: Fix !SMP build error per kernel test robot feedback. ]
Signed-off-by: Paul E
From: Thomas Gleixner
CONFIG_PREEMPT_COUNT is now unconditionally enabled and will be
removed. Cleanup the leftovers before doing so.
Signed-off-by: Thomas Gleixner
Cc: Peter Zijlstra
Cc: Ingo Molnar
Cc: Will Deacon
Acked-by: Will Deacon
Signed-off-by: Paul E. McKenney
---
include/linux/l
From: Thomas Gleixner
ARCH_NO_PREEMPT disables the selection of CONFIG_PREEMPT_VOLUNTARY and
CONFIG_PREEMPT, but architectures which set this config option still
support preempt count for hard and softirq accounting.
There is absolutely no reason to prevent lockdep from using the preempt
counter
From: Thomas Gleixner
All conditionals and irritations are gone.
Signed-off-by: Thomas Gleixner
Signed-off-by: Paul E. McKenney
---
kernel/Kconfig.preempt | 3 ---
1 file changed, 3 deletions(-)
diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index 3f4712f..120b63f 100644
--- a/
From: Thomas Gleixner
CONFIG_PREEMPT_COUNT is now unconditionally enabled and will be
removed. Cleanup the leftovers before doing so.
Signed-off-by: Thomas Gleixner
Cc: Chris Zankel
Cc: Max Filippov
Cc: linux-xte...@linux-xtensa.org
Signed-off-by: Paul E. McKenney
---
arch/xtensa/kernel/ent
From: kernel test robot
NULL check before kfree is not needed.
Generated by: scripts/coccinelle/free/ifnullfree.cocci
Fixes: 9f7e887e648c ("rcu/tree: Allocate a page when caller is preemptible")
Acked-by: Joel Fernandes (Google)
Signed-off-by: kernel test robot
Signed-off-by: Julia Lawall
Si
From: Thomas Gleixner
CONFIG_PREEMPT_COUNT is now unconditionally enabled and will be
removed. Cleanup the leftovers before doing so.
Signed-off-by: Thomas Gleixner
Acked-by: Will Deacon
Signed-off-by: Paul E. McKenney
---
include/linux/bit_spinlock.h | 4 +---
1 file changed, 1 insertion(+)
From: Thomas Gleixner
CONFIG_PREEMPT_COUNT is now unconditionally enabled and will be
removed. Cleanup the leftovers before doing so.
Signed-off-by: Thomas Gleixner
Cc: Jani Nikula
Cc: Joonas Lahtinen
Cc: Rodrigo Vivi
Cc: David Airlie
Cc: Daniel Vetter
Cc: intel-...@lists.freedesktop.org
C
From: Thomas Gleixner
CONFIG_PREEMPT_COUNT is now unconditionally enabled and will be
removed. Cleanup the leftovers before doing so.
Signed-off-by: Thomas Gleixner
Signed-off-by: Paul E. McKenney
---
include/linux/uaccess.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --
From: Thomas Gleixner
CONFIG_PREEMPT_COUNT is now unconditionally enabled and will be
removed. Cleanup the leftovers before doing so.
Signed-off-by: Thomas Gleixner
Cc: Ingo Molnar
Cc: Peter Zijlstra
Cc: Juri Lelli
Cc: Vincent Guittot
Cc: Dietmar Eggemann
Cc: Steven Rostedt
Cc: Ben Segall
From: Tobias Klauser
s/sychronize_rcu/synchronize_rcu/
Signed-off-by: Tobias Klauser
Signed-off-by: Paul E. McKenney
---
Documentation/RCU/whatisRCU.rst | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/Documentation/RCU/whatisRCU.rst b/Documentation/RCU/whatisRCU.rst
index
From: Randy Dunlap
Drop the doubled word "the".
Signed-off-by: Randy Dunlap
Cc: Jonathan Corbet
Cc: linux-...@vger.kernel.org
Cc: "Paul E. McKenney"
Cc: Josh Triplett
Cc: Steven Rostedt
Cc: Mathieu Desnoyers
Cc: Lai Jiangshan
Cc: Joel Fernandes
Cc: r...@vger.kernel.org
Signed-off-by: Pau
From: Randy Dunlap
Drop the doubled words "to" and "for".
Signed-off-by: Randy Dunlap
Cc: Jonathan Corbet
Cc: linux-...@vger.kernel.org
Cc: "Paul E. McKenney"
Cc: Josh Triplett
Cc: Steven Rostedt
Cc: Mathieu Desnoyers
Cc: Lai Jiangshan
Cc: Joel Fernandes
Cc: r...@vger.kernel.org
Signed-o
From: "Paul E. McKenney"
Given that sysfs can change the value of rcu_divisor at any time, this
commit adds a READ_ONCE to the sole access to that variable. While in
the area, this commit also adds bounds checking, clamping the value to
a shift that makes sense for a signed long.
Signed-off-by:
From: Neeraj Upadhyay
On callback overload, it is necessary to quickly detect idle CPUs,
and rcu_gp_fqs_check_wake() checks for this condition. Unfortunately,
the code following the call to this function does not repeat this check,
which means that in reality no actual quiescent-state forcing, i
From: "Paul E. McKenney"
This commit increases RCU's ability to defend itself by emitting a warning
if one of the nocb CB kthreads invokes the GP kthread's wait function.
This warning augments a similar check that is carried out at the end
of rcutorture testing and when RCU CPU stall warnings are
From: Zqiang
CPUs can go offline shortly after kfree_call_rcu() has been invoked,
which can leave memory stranded until those CPUs come back online.
This commit therefore drains the kcrp of each CPU, not just the
ones that happen to be online.
Acked-by: Joel Fernandes
Signed-off-by: Zqiang
Sig
From: "Joel Fernandes (Google)"
The RCU grace-period kthread's force-quiescent state (FQS) loop should
never see an offline CPU that has not yet reported a quiescent state.
After all, the offline CPU should have reported a quiescent state
during the CPU-offline process, or, failing that, by rcu_g
From: "Paul E. McKenney"
Given that sysfs can change the value of rcu_kick_kthreads at any time,
this commit adds a READ_ONCE() to the sole access to that variable.
Signed-off-by: Paul E. McKenney
---
kernel/rcu/tree_stall.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git
From: "Paul E. McKenney"
KCSAN is now in mainline, so this commit removes the stubs for the
data_race(), ASSERT_EXCLUSIVE_WRITER(), and ASSERT_EXCLUSIVE_ACCESS()
macros.
Signed-off-by: Paul E. McKenney
---
kernel/rcu/srcutree.c | 13 -
1 file changed, 13 deletions(-)
diff --git a/
From: "Paul E. McKenney"
The x86/entry work removed all uses of __rcu_is_watching(), therefore
this commit removes it entirely.
Cc: Andy Lutomirski
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: Borislav Petkov
Cc: "H. Peter Anvin"
Cc:
Signed-off-by: Paul E. McKenney
---
include/linux/rcutiny.h
-+-+
The reduction in the number of wakeups ranges from 5% to 40%.
Cc: ure...@gmail.com
[ paulmck: Rework commit log and comment. ]
Signed-off-by: Joel Fernandes (Google)
Signed-off-by: Paul E. McKenney
---
kernel/rcu/rcu_segcblist.c | 10 +-
1 file changed, 9 insertion
From: "Paul E. McKenney"
When the rcu_cpu_started per-CPU variable was added by commit
f64c6013a202 ("rcu/x86: Provide early rcu_cpu_starting() callback"),
there were multiple sets of per-CPU rcu_data structures. Therefore, the
rcu_cpu_started flag was added as a separate per-CPU variable. But
From: "Paul E. McKenney"
KCSAN is now in mainline, so this commit removes the stubs for the
data_race(), ASSERT_EXCLUSIVE_WRITER(), and ASSERT_EXCLUSIVE_ACCESS()
macros.
Signed-off-by: Paul E. McKenney
---
kernel/rcu/update.c | 13 -
1 file changed, 13 deletions(-)
diff --git a/ke
From: Madhuparna Bhowmik
Use hlist_for_each_entry_srcu() instead of hlist_for_each_entry_rcu()
as it also checkes if the right lock is held.
Using hlist_for_each_entry_rcu() with a condition argument will not
report the cases where a SRCU protected list is traversed using
rcu_read_lock(). Hence,
From: "Paul E. McKenney"
This commit moves the initialization of the CONFIG_PREEMPT=n version of
the rcu_exp_handler() function's rdp and rnp local variables into their
respective declarations to save a couple lines of code.
Signed-off-by: Paul E. McKenney
---
kernel/rcu/tree_exp.h | 6 ++
From: "Paul E. McKenney"
Given that sysfs can change the value of rcu_cpu_stall_ftrace_dump at any
time, this commit adds a READ_ONCE() to the accesses to that variable.
Signed-off-by: Paul E. McKenney
---
kernel/rcu/tree_stall.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff
From: Neeraj Upadhyay
Originally, the call to rcu_preempt_blocked_readers_cgp() from
force_qs_rnp() had to be conditioned on CONFIG_PREEMPT_RCU=y, as in
commit a77da14ce9af ("rcu: Yet another fix for preemption and CPU
hotplug"). However, there is now a CONFIG_PREEMPT_RCU=n definition of
rcu_pre
From: Tobias Klauser
This commit fixes the kerneldoc comments for rcu_read_unlock_bh(),
rcu_read_unlock_sched() and rcu_head_after_call_rcu() so they e.g. get
properly linked in the API documentation. Also add parenthesis after
function names to match the notation used in other kerneldoc comments
From: "Paul E. McKenney"
KCSAN is now in mainline, so this commit removes the stubs for the
data_race(), ASSERT_EXCLUSIVE_WRITER(), and ASSERT_EXCLUSIVE_ACCESS()
macros.
Signed-off-by: Paul E. McKenney
---
kernel/rcu/tree.c | 13 -
1 file changed, 13 deletions(-)
diff --git a/kern
From: "Paul E. McKenney"
The rcu_data structure's ->nocb_timer field is used to defer wakeups of
the corresponding no-CBs CPU's grace-period kthread ("rcuog*"), and that
structure's ->nocb_defer_wakeup field is used to track such deferral.
This means that the show_rcu_nocb_state() printing an err
srcu_read_lock_head() can be passed as the cond argument to
list/hlist_for_each_entry_srcu().
Suggested-by: Paolo Bonzini
Tested-by: Suraj Upadhyay
Tested-by: Naresh Kamboju
[ paulmck: Add "true" per kbuild test robot feedback. ]
Signed-off-by: Madhuparna Bhowmik
Signed-off-by: Paul E
From: "Joel Fernandes (Google)"
Since at least v4.19, the FQS loop no longer reports quiescent states
for offline CPUs except in emergency situations.
This commit therefore fixes the comment in rcu_gp_init() to match the
current code.
Signed-off-by: Joel Fernandes (Google)
Signed-off-by: Paul
From: "Paul E. McKenney"
Given that sysfs can change the value of rcu_resched_ns at any time,
this commit adds a READ_ONCE() to the sole access to that variable.
While in the area, this commit also adds bounds checking, clamping the
value to at least a millisecond, but no longer than a second.
S
umber (for example, Tiny RCU)
just print zeroes.
[ paulmck: Adjust commit log. ]
Signed-off-by: Joel Fernandes (Google)
Signed-off-by: Paul E. McKenney
---
kernel/rcu/rcutorture.c | 13 +++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/rcutorture.c b/
From: "Joel Fernandes (Google)"
GP numbers start from -300 and gp_seq numbers start of -1200 (for a
shift of 2). These negative numbers are printed as unsigned long which
not only takes up more text space, but is rather confusing to the reader
as they have to constantly expend energy to truncate
From: "Paul E. McKenney"
A message of the form "rcu:!!! lDTs ." can be tracked down, but
doing so is not trivial. This commit therefore eases this process by
adding text so that this error message now reads as follows:
"rcu:nocb GP activity on CB-only CPU!!! lDTs ."
Signed-off-by: Paul
From: "Joel Fernandes (Google)"
During acceleration of CB, the rsp's gp_seq is rcu_seq_snap'd. This is
the value used for acceleration - it is the value of gp_seq at which it
is safe the execute all callbacks in the callback list.
The rdp's gp_seq is not very useful for this scenario. Make
rcu_g
From: "Paul E. McKenney"
The current rcutorture forward-progress code assumes that it is the
only cause of out-of-memory (OOM) events. For script-based rcutorture
testing, this assumption is in fact correct. However, testing based
on modprobe/rmmod might well encounter external OOM events, whic
From: Colin Ian King
Currently in the unlikely event that buf fails to be allocated it
is dereferenced a few times. Use the errexit flag to determine if
buf should be written to to avoid the null pointer dereferences.
Addresses-Coverity: ("Dereference after null check")
Fixes: f518f154ecef ("re
From: "Paul E. McKenney"
The conversion of rcu_fwds to dynamic allocation failed to actually
allocate the required structure. This commit therefore allocates it,
frees it, and updates rcu_fwds accordingly. While in the area, it
abstracts the cleanup actions into rcu_torture_fwd_prog_cleanup().
From: "Paul E. McKenney"
This commit adds an rcutorture.leakpointer module parameter that
intentionally leaks an RCU-protected pointer out of the RCU read-side
critical section and checks to see if the corresponding grace period
has elapsed, emitting a WARN_ON_ONCE() if so. This module parameter
From: "Paul E. McKenney"
This commit adds a "--gdb" parameter to kvm.sh, which causes
"CONFIG_DEBUG_INFO=y" to be added to the Kconfig options, "nokaslr"
to be added to the boot parameters, and "-s -S" to be added to the qemu
arguments. Furthermore, the scripting prints messages telling the user
From: "Paul E. McKenney"
This commit adds a --help argument (along with its synonym -h) to display
the help text. While in the area, this commit also updates the help text.
Signed-off-by: Paul E. McKenney
---
tools/testing/selftests/rcutorture/bin/kvm.sh | 8 ++--
1 file changed, 6 insert
From: "Paul E. McKenney"
KCSAN is now in mainline, so this commit removes the stubs for the
data_race(), ASSERT_EXCLUSIVE_WRITER(), and ASSERT_EXCLUSIVE_ACCESS()
macros.
Signed-off-by: Paul E. McKenney
---
kernel/rcu/rcutorture.c | 13 -
1 file changed, 13 deletions(-)
diff --git
From: "Alexander A. Klimov"
Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.
Deterministic algorithm:
For each file:
If not .svg:
For each line:
If doesn't contain `\bxmlns\b`:
For each link, `\bhttp://
From: "Paul E. McKenney"
Currently, registering and unregistering the OOM notifier is done
right before and after the test, respectively. This will not work
well for multi-threaded tests, so this commit hoists this registering
and unregistering up into the rcu_torture_fwd_prog_init() and
rcu_tor
From: "Paul E. McKenney"
The rcu-test-image.txt documentation covers a very uncommon case where
a real userspace environment is required. However, someone reading this
document might reasonably conclude that this is in fact a prerequisite.
In addition, the initrd.txt file mentions dracut, which
From: "Paul E. McKenney"
Currently, the CONFIG_PROVE_RCU_LIST=y case is untested. This commit
therefore adds CONFIG_PROVE_RCU_LIST=y to rcutorture's TREE05 scenario.
Cc: Madhuparna Bhowmik
Cc: Joel Fernandes (Google)
Signed-off-by: Paul E. McKenney
---
tools/testing/selftests/rcutorture/con
From: Wei Yongjun
The sparse tool complains as follows:
kernel/locking/locktorture.c:569:6: warning:
symbol 'torture_percpu_rwsem_init' was not declared. Should it be static?
And this function is not used outside of locktorture.c,
so this commit marks it static.
Signed-off-by: Wei Yongjun
Si
From: Paul Gortmaker
Signed-off-by: Paul Gortmaker
Signed-off-by: Paul E. McKenney
---
tools/testing/selftests/rcutorture/bin/kvm.sh | 1 +
1 file changed, 1 insertion(+)
diff --git a/tools/testing/selftests/rcutorture/bin/kvm.sh
b/tools/testing/selftests/rcutorture/bin/kvm.sh
index e655983.
From: "Paul E. McKenney"
Currently, parse-torture.sh looks at the fifth field of torture-test
console output for the version number. This works fine for rcutorture,
but not for scftorture, which lacks the pointer field. This commit
therefore adjusts matching lines so that the parse-console.sh a
g into the handler in the no-wait case because none
of the handlers would be able to free the scf_check structure without
introducing heavy synchronization to work out which was last.
[ paulmck: s/GFP_KERNEL/GFP_ATOMIC/ per kernel test robot feedback. ]
Signed-off-by: Paul E. McKenney
-
From: "Paul E. McKenney"
This commit adds a "default" case to the switch statement in
scftorture_invoke_one() which contains a WARN_ON_ONCE() and an assignment
to ->scfc_out to suppress knock-on warnings. These knock-on warnings
could otherwise cause the user to think that there was a memory-ord
From: "Paul E. McKenney"
Currently, CPU-hotplug operations might result in all but two
of (say) 100 CPUs being offline, which in turn might result in
false-positive diagnostics due to overload. This commit therefore
causes scftorture_invoker() kthreads for offline CPUs to loop blocking
for 200 m
From: "Paul E. McKenney"
Currently, can_stop_idle_tick() prints "NOHZ: local_softirq_pending HH"
(where "HH" is the hexadecimal softirq vector number) when one or more
non-RCU softirq handlers are still enabled when checking to stop the
scheduler-tick interrupt. This message is not as enlighteni
From: "Paul E. McKenney"
On uniprocessor systems, smp_call_function() does nothing. This commit
therefore avoids complaining about the lack of handler accesses in the
single-CPU case where there is no handler.
Signed-off-by: Paul E. McKenney
---
kernel/scftorture.c | 3 ++-
1 file changed, 2
From: "Paul E. McKenney"
This commit prints error counts on the statistics line and also adds a
"!!!" if any of the counters are non-zero. Allocation failures are
(somewhat) forgiven, but all other errors result in a "FAILURE" print
at the end of the test.
Signed-off-by: Paul E. McKenney
---
From: "Paul E. McKenney"
Detecting smp_call_function() memory misordering requires close timing,
so it is necessary to have the checks immediately before and after
the call to the smp_call_function*() function under test. This commit
therefore inserts barrier() calls to prevent the compiler from
From: "Paul E. McKenney"
Although the test loop does randomly delay, which would provide quiescent
states and so forth, it is possible for there to be a series of long
smp_call_function*() handler runtimes with no delays, which results in
softlockup and RCU CPU stall warning messages. This commi
ering into the handler in the no-wait case because none
of the handlers would be able to free the scf_check structure without
introducing heavy synchronization to work out which was last.
[ paulmck: s/GFP_KERNEL/GFP_ATOMIC/ per kernel test robot feedback. ]
Signed-off-by: Paul E. McKenney
-
From: "Paul E. McKenney"
This commit moves checking of the ->scfc_out field and the freeing of
the scf_check structure down below the end of switch statement, thus
saving a few lines of code.
Signed-off-by: Paul E. McKenney
---
kernel/scftorture.c | 26 --
1 file change
From: "Paul E. McKenney"
This commit adds checks for memory misordering across calls to
smp_call_function_single() and also across returns in the case where
the caller waits. Misordering results in a splat.
[ paulmck: s/GFP_KERNEL/GFP_ATOMIC/ per kernel test robot feedback. ]
Sig
From: "Paul E. McKenney"
This commit uses the scftorture.weight* kernel parameters to randomly
chooses between smp_call_function_single(), smp_call_function_many(),
and smp_call_function(). For each variant, it also randomly chooses
whether to invoke it synchronously (wait=1) or asynchronously (
From: "Paul E. McKenney"
This commit adds an smp_call_function() torture test that repeatedly
invokes this function and complains if things go badly awry.
Signed-off-by: Paul E. McKenney
---
Documentation/admin-guide/kernel-parameters.txt | 92 +++
kernel/Makefile
From: "Paul E. McKenney"
This commit updates the rcutorture scripting to include the new scftorture
torture-test module.
Signed-off-by: Paul E. McKenney
---
.../selftests/rcutorture/bin/kvm-recheck-scf.sh| 38 ++
tools/testing/selftests/rcutorture/bin/kvm.sh | 2 +
he names of the kernel boot
parameters, so kernel-parameters.txt and ver_functions.sh are also
updated. The rcutorture --torture type was also updated from rcuperf
to rcuscale.
[ paulmck: Fix bugs located by Stephen Rothwell. ]
Reported-by: Ingo Molnar
Signed-off-by: Paul E. McKenney
---
Docu
From: Wei Yongjun
The sparse tool complains as follows
kernel/scftorture.c:124:1: warning:
symbol '__pcpu_scope_scf_torture_rand' was not declared. Should it be static?
And this per-CPU variable is not used outside of scftorture.c,
so this commit marks it static.
Reported-by: Hulk Robot
Sign
From: "Paul E. McKenney"
This commit hoists much of the initialization of the scf_check
structure out of the switch statement, thus saving a few lines of code.
The initialization of the ->scfc_in field remains in each leg of the
switch statement in order to more heavily stress memory ordering.
S
From: "Paul E. McKenney"
This commit summarizes the per-thread statistics, providing counts of
the number of single, many, and all calls, both no-wait and wait, and,
for the single case, the number where the target CPU was offline.
Signed-off-by: Paul E. McKenney
---
kernel/scftorture.c | 22 +
From: "Paul E. McKenney"
The value of DEFAULT_RCU_BLIMIT is normally set to 10, the idea being to
avoid needless response-time degradation due to RCU callback invocation.
However, when CONFIG_RCU_STRICT_GRACE_PERIOD=y it is better to avoid
throttling callback execution in order to better detect p
From: "Paul E. McKenney"
Currently, each CPU discovers the beginning of a given grace period
on its own time, which is again good for efficiency but bad for fast
grace periods. This commit therefore uses on_each_cpu() to IPI each
CPU after grace-period initialization in order to inform each CPU
From: "Paul E. McKenney"
The "cpu" parameter to rcu_report_qs_rdp() is not used, with rdp->cpu
being used instead. Furtheremore, every call to rcu_report_qs_rdp()
invokes it on rdp->cpu. This commit therefore removes this unused "cpu"
parameter and converts a check of rdp->cpu against smp_proce
uested via rcutree.rcu_unlock_delay. This commit also adds a call
to rcu_read_unlock_strict() from the CONFIG_PREEMPT=n instance of
__rcu_read_unlock().
[ paulmck: Fixed bug located by kernel test robot ]
Reported-by Jann Horn
Signed-off-by: Paul E. McKenney
---
include/linux/rcupdate.h | 7 +++
kernel/
From: "Paul E. McKenney"
Because strict RCU grace periods will complete more quickly, they will
experience greater lock contention on each leaf rcu_node structure's
->lock. This commit therefore reduces the leaf fanout in order to reduce
this lock contention.
Note that this also has the effect
From: "Paul E. McKenney"
A kernel built with CONFIG_RCU_STRICT_GRACE_PERIOD=y needs a quiescent
state to appear very shortly after a CPU has noticed a new grace period.
Placing an RCU reader immediately after this point is ineffective because
this normally happens in softirq context, which acts a
From: "Paul E. McKenney"
If there are idle CPUs, RCU's grace-period kthread will wait several
jiffies before even thinking about polling them. This promotes
efficiency, which is normally a good thing, but when the kernel
has been built with CONFIG_RCU_STRICT_GRACE_PERIOD=y, we care more
about sh
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