Changes in 5.15.39
MIPS: Fix CP0 counter erratum detection for R4k CPUs
parisc: Merge model and model name into one line in /proc/cpuinfo
ALSA: hda/realtek: Add quirk for Yoga Duet 7 13ITL6 speakers
ALSA: fireworks: fix wrong return count shorter than expected by 4 bytes
mmc: sdhci-msm: Reset GCC_SDCC_BCR register for SDHC
mmc: sunxi-mmc: Fix DMA descriptors allocated above 32 bits
mmc: core: Set HS clock speed before sending HS CMD13
gpiolib: of: fix bounds check for 'gpio-reserved-ranges'
x86/fpu: Prevent FPU state corruption
KVM: x86/svm: Account for family 17h event renumberings in amd_pmc_perf_hw_id
iommu/vt-d: Calculate mask for non-aligned flushes
iommu/arm-smmu-v3: Fix size calculation in arm_smmu_mm_invalidate_range()
drm/amd/display: Avoid reading audio pattern past AUDIO_CHANNELS_COUNT
drm/amdgpu: do not use passthrough mode in Xen dom0
RISC-V: relocate DTB if it's outside memory region
Revert "SUNRPC: attempt AF_LOCAL connect on setup"
timekeeping: Mark NMI safe time accessors as notrace
firewire: fix potential uaf in outbound_phy_packet_callback()
firewire: remove check of list iterator against head past the loop body
firewire: core: extend card->lock in fw_core_handle_bus_reset
net: stmmac: disable Split Header (SPH) for Intel platforms
genirq: Synchronize interrupt thread startup
ASoC: da7219: Fix change notifications for tone generator frequency
ASoC: wm8958: Fix change notifications for DSP controls
ASoC: meson: Fix event generation for AUI ACODEC mux
ASoC: meson: Fix event generation for G12A tohdmi mux
ASoC: meson: Fix event generation for AUI CODEC mux
s390/dasd: fix data corruption for ESE devices
s390/dasd: prevent double format of tracks for ESE devices
s390/dasd: Fix read for ESE with blksize < 4k
s390/dasd: Fix read inconsistency for ESE DASD devices
can: grcan: grcan_close(): fix deadlock
can: isotp: remove re-binding of bound socket
can: grcan: use ofdev->dev when allocating DMA memory
can: grcan: grcan_probe(): fix broken system id check for errata workaround needs
can: grcan: only use the NAPI poll budget for RX
nfc: replace improper check device_is_registered() in netlink related functions
nfc: nfcmrvl: main: reorder destructive operations in nfcmrvl_nci_unregister_dev to avoid bugs
NFC: netlink: fix sleep in atomic bug when firmware download timeout
gpio: visconti: Fix fwnode of GPIO IRQ
gpio: pca953x: fix irq_stat not updated when irq is disabled (irq_mask not set)
hwmon: (adt7470) Fix warning on module removal
hwmon: (pmbus) disable PEC if not enabled
ASoC: dmaengine: Restore NULL prepare_slave_config() callback
ASoC: soc-ops: fix error handling
iommu/vt-d: Drop stop marker messages
iommu/dart: check return value after calling platform_get_resource()
net/mlx5e: Fix trust state reset in reload
net/mlx5e: Don't match double-vlan packets if cvlan is not set
net/mlx5e: CT: Fix queued up restore put() executing after relevant ft release
net/mlx5e: Fix the calling of update_buffer_lossy() API
net/mlx5: Avoid double clear or set of sync reset requested
net/mlx5: Fix deadlock in sync reset flow
selftests/seccomp: Don't call read() on TTY from background pgrp
SUNRPC release the transport of a relocated task with an assigned transport
RDMA/siw: Fix a condition race issue in MPA request processing
RDMA/irdma: Flush iWARP QP if modified to ERR from RTR state
RDMA/irdma: Reduce iWARP QP destroy time
RDMA/irdma: Fix possible crash due to NULL netdev in notifier
NFSv4: Don't invalidate inode attributes on delegation return
net: ethernet: mediatek: add missing of_node_put() in mtk_sgmii_init()
net: dsa: mt7530: add missing of_node_put() in mt7530_setup()
net: stmmac: dwmac-sun8i: add missing of_node_put() in sun8i_dwmac_register_mdio_mux()
net: mdio: Fix ENOMEM return value in BCM6368 mux bus controller
net: cpsw: add missing of_node_put() in cpsw_probe_dt()
net: igmp: respect RCU rules in ip_mc_source() and ip_mc_msfilter()
net: emaclite: Add error handling for of_address_to_resource()
selftests/net: so_txtime: fix parsing of start time stamp on 32 bit systems
selftests/net: so_txtime: usage(): fix documentation of default clock
drm/msm/dp: remove fail safe mode related code
btrfs: do not BUG_ON() on failure to update inode when setting xattr
hinic: fix bug of wq out of bound access
mld: respect RCU rules in ip6_mc_source() and ip6_mc_msfilter()
rxrpc: Enable IPv6 checksums on transport socket
selftests: mirror_gre_bridge_1q: Avoid changing PVID while interface is operational
bnxt_en: Fix possible bnxt_open() failure caused by wrong RFS flag
bnxt_en: Fix unnecessary dropping of RX packets
selftests: ocelot: tc_flower_chains: specify conform-exceed action for policer
smsc911x: allow using IRQ0
btrfs: force v2 space cache usage for subpage mount
btrfs: always log symlinks in full mode
drm/amdgpu: unify BO evicting method in amdgpu_ttm
drm/amdgpu: explicitly check for s0ix when evicting resources
drm/amdgpu: don't set s3 and s0ix at the same time
drm/amdgpu: Ensure HDA function is suspended before ASIC reset
gpio: mvebu: drop pwm base assignment
kvm: x86/cpuid: Only provide CPUID leaf 0xA if host has architectural PMU
fbdev: Make fb_release() return -ENODEV if fbdev was unregistered
net/mlx5: Fix slab-out-of-bounds while reading resource dump menu
net/mlx5e: Lag, Fix use-after-free in fib event handler
net/mlx5e: Lag, Fix fib_info pointer assignment
net/mlx5e: Lag, Don't skip fib events on current dst
iommu/dart: Add missing module owner to ops structure
kvm: selftests: do not use bitfields larger than 32-bits for PTEs
KVM: selftests: Silence compiler warning in the kvm_page_table_test
x86/kvm: Preserve BSP MSR_KVM_POLL_CONTROL across suspend/resume
KVM: x86: Do not change ICR on write to APIC_SELF_IPI
KVM: x86/mmu: avoid NULL-pointer dereference on page freeing bugs
KVM: LAPIC: Enable timer posted-interrupt only when mwait/hlt is advertised
selftest/vm: verify mmap addr in mremap_test
selftest/vm: verify remap destination address in mremap_test
mmc: rtsx: add 74 Clocks in power on flow
Revert "parisc: Mark sched_clock unstable only if clocks are not syncronized"
rcu: Fix callbacks processing time limit retaining cond_resched()
rcu: Apply callbacks processing time limit only on softirq
PCI: pci-bridge-emul: Add description for class_revision field
PCI: pci-bridge-emul: Add definitions for missing capabilities registers
PCI: aardvark: Add support for DEVCAP2, DEVCTL2, LNKCAP2 and LNKCTL2 registers on emulated bridge
PCI: aardvark: Clear all MSIs at setup
PCI: aardvark: Comment actions in driver remove method
PCI: aardvark: Disable bus mastering when unbinding driver
PCI: aardvark: Mask all interrupts when unbinding driver
PCI: aardvark: Fix memory leak in driver unbind
PCI: aardvark: Assert PERST# when unbinding driver
PCI: aardvark: Disable link training when unbinding driver
PCI: aardvark: Disable common PHY when unbinding driver
PCI: aardvark: Replace custom PCIE_CORE_INT_* macros with PCI_INTERRUPT_*
PCI: aardvark: Rewrite IRQ code to chained IRQ handler
PCI: aardvark: Check return value of generic_handle_domain_irq() when processing INTx IRQ
PCI: aardvark: Make MSI irq_chip structures static driver structures
PCI: aardvark: Make msi_domain_info structure a static driver structure
PCI: aardvark: Use dev_fwnode() instead of of_node_to_fwnode(dev->of_node)
PCI: aardvark: Refactor unmasking summary MSI interrupt
PCI: aardvark: Add support for masking MSI interrupts
PCI: aardvark: Fix setting MSI address
PCI: aardvark: Enable MSI-X support
PCI: aardvark: Add support for ERR interrupt on emulated bridge
PCI: aardvark: Optimize writing PCI_EXP_RTCTL_PMEIE and PCI_EXP_RTSTA_PME on emulated bridge
PCI: aardvark: Add support for PME interrupts
PCI: aardvark: Fix support for PME requester on emulated bridge
PCI: aardvark: Use separate INTA interrupt for emulated root bridge
PCI: aardvark: Remove irq_mask_ack() callback for INTx interrupts
PCI: aardvark: Don't mask irq when mapping
PCI: aardvark: Drop __maybe_unused from advk_pcie_disable_phy()
PCI: aardvark: Update comment about link going down after link-up
Linux 5.15.39
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Ibd053f0980e7d7eb5659ec6cfa7689c6d9bc416e
The default kasan_record_aux_stack() calls stack_depot_save() with GFP_NOWAIT,
which in turn can then call alloc_pages(GFP_NOWAIT, ...). In general, however,
it is not even possible to use either GFP_ATOMIC nor GFP_NOWAIT in certain
non-preemptive contexts/RT kernel including raw_spin_locks (see gfp.h and ab00db216c).
Fix it by instructing stackdepot to not expand stack storage via alloc_pages()
in case it runs out by using kasan_record_aux_stack_noalloc().
Jianwei Hu reported:
BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:969
in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 15319, name: python3
INFO: lockdep is turned off.
irq event stamp: 0
hardirqs last enabled at (0): [<0000000000000000>] 0x0
hardirqs last disabled at (0): [<ffffffff856c8b13>] copy_process+0xaf3/0x2590
softirqs last enabled at (0): [<ffffffff856c8b13>] copy_process+0xaf3/0x2590
softirqs last disabled at (0): [<0000000000000000>] 0x0
CPU: 6 PID: 15319 Comm: python3 Tainted: G W O 5.15-rc7-preempt-rt #1
Hardware name: Supermicro SYS-E300-9A-8C/A2SDi-8C-HLN4F, BIOS 1.1b 12/17/2018
Call Trace:
show_stack+0x52/0x58
dump_stack+0xa1/0xd6
___might_sleep.cold+0x11c/0x12d
rt_spin_lock+0x3f/0xc0
rmqueue+0x100/0x1460
rmqueue+0x100/0x1460
mark_usage+0x1a0/0x1a0
ftrace_graph_ret_addr+0x2a/0xb0
rmqueue_pcplist.constprop.0+0x6a0/0x6a0
__kasan_check_read+0x11/0x20
__zone_watermark_ok+0x114/0x270
get_page_from_freelist+0x148/0x630
is_module_text_address+0x32/0xa0
__alloc_pages_nodemask+0x2f6/0x790
__alloc_pages_slowpath.constprop.0+0x12d0/0x12d0
create_prof_cpu_mask+0x30/0x30
alloc_pages_current+0xb1/0x150
stack_depot_save+0x39f/0x490
kasan_save_stack+0x42/0x50
kasan_save_stack+0x23/0x50
kasan_record_aux_stack+0xa9/0xc0
__call_rcu+0xff/0x9c0
call_rcu+0xe/0x10
put_object+0x53/0x70
__delete_object+0x7b/0x90
kmemleak_free+0x46/0x70
slab_free_freelist_hook+0xb4/0x160
kfree+0xe5/0x420
kfree_const+0x17/0x30
kobject_cleanup+0xaa/0x230
kobject_put+0x76/0x90
netdev_queue_update_kobjects+0x17d/0x1f0
... ...
ksys_write+0xd9/0x180
__x64_sys_write+0x42/0x50
do_syscall_64+0x38/0x50
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Links: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/include/linux/kasan.h?id=7cb3007ce2da27ec02a1a3211941e7fe6875b642
Fixes: 84109ab585 ("rcu: Record kvfree_call_rcu() call stack for KASAN")
Fixes: 26e760c9a7 ("rcu: kasan: record and print call_rcu() call stack")
Reported-by: Jianwei Hu <jianwei.hu@windriver.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Acked-by: Marco Elver <elver@google.com>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Jun Miao <jun.miao@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
(cherry picked from commit 300c0c5e721834f484b03fa3062602dd8ff48413)
Bug: 217222520
Change-Id: I5b7d4f9dfe5da290627599d8d6de3278debb2a13
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
commit 614ddad17f22a22e035e2ea37a04815f50362017 upstream.
Currently, rcu_advance_cbs_nowake() checks that a grace period is in
progress, however, that grace period could end just after the check.
This commit rechecks that a grace period is still in progress while
holding the rcu_node structure's lock. The grace period cannot end while
the current CPU's rcu_node structure's ->lock is held, thus avoiding
false positives from the WARN_ON_ONCE().
As Daniel Vacek noted, it is not necessary for the rcu_node structure
to have a CPU that has not yet passed through its quiescent state.
Tested-by: Guillaume Morin <guillaume@morinfr.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There are a few remaining locations in kernel/rcu that still use
"&per_cpu()". This commit replaces them with "per_cpu_ptr(&)", and does
not introduce any functional change.
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Liu Song <liu.song11@zte.com.cn>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Within rcu_gp_fqs_loop(), the "ret" local variable is set to the
return value from swait_event_idle_timeout_exclusive(), but "ret" is
unconditionally overwritten later in the code. This commit therefore
removes this useless assignment.
Signed-off-by: Liu Song <liu.song11@zte.com.cn>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The kbuild test project found an oversized stack frame in rcu_gp_kthread()
for some kernel configurations. This oversizing was due to a very large
amount of inlining, which is unnecessary due to the fact that this code
executes infrequently. This commit therefore marks rcu_gp_init() and
rcu_gp_fqs_loop noinline_for_stack to conserve stack space.
Reported-by: kernel test robot <lkp@intel.com>
Tested-by: Rong Chen <rong.a.chen@intel.com>
[ paulmck: noinline_for_stack per Nathan Chancellor. ]
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Accesses to the rcu_data structure's ->dynticks field have always been
fully ordered because it was not possible to prove that weaker ordering
was safe. However, with the removal of the rcu_eqs_special_set() function
and the advent of the Linux-kernel memory model, it is now easy to show
that two of the four original full memory barriers can be weakened to
acquire and release operations. The remaining pair must remain full
memory barriers. This change makes the memory ordering requirements
more evident, and it might well also speed up the to-idle and from-idle
fastpaths on some architectures.
The following litmus test, adapted from one supplied off-list by Frederic
Weisbecker, models the RCU grace-period kthread detecting an idle CPU
that is concurrently transitioning to non-idle:
C dynticks-from-idle
{
DYNTICKS=0; (* Initially idle. *)
}
P0(int *X, int *DYNTICKS)
{
int dynticks;
int x;
// Idle.
dynticks = READ_ONCE(*DYNTICKS);
smp_store_release(DYNTICKS, dynticks + 1);
smp_mb();
// Now non-idle
x = READ_ONCE(*X);
}
P1(int *X, int *DYNTICKS)
{
int dynticks;
WRITE_ONCE(*X, 1);
smp_mb();
dynticks = smp_load_acquire(DYNTICKS);
}
exists (1:dynticks=0 /\ 0:x=1)
Running "herd7 -conf linux-kernel.cfg dynticks-from-idle.litmus" verifies
this transition, namely, showing that if the RCU grace-period kthread (P1)
sees another CPU as idle (P0), then any memory access prior to the start
of the grace period (P1's write to X) will be seen by any RCU read-side
critical section following the to-non-idle transition (P0's read from X).
This is a straightforward use of full memory barriers to force ordering
in a store-buffering (SB) litmus test.
The following litmus test, also adapted from the one supplied off-list
by Frederic Weisbecker, models the RCU grace-period kthread detecting
a non-idle CPU that is concurrently transitioning to idle:
C dynticks-into-idle
{
DYNTICKS=1; (* Initially non-idle. *)
}
P0(int *X, int *DYNTICKS)
{
int dynticks;
// Non-idle.
WRITE_ONCE(*X, 1);
dynticks = READ_ONCE(*DYNTICKS);
smp_store_release(DYNTICKS, dynticks + 1);
smp_mb();
// Now idle.
}
P1(int *X, int *DYNTICKS)
{
int x;
int dynticks;
smp_mb();
dynticks = smp_load_acquire(DYNTICKS);
x = READ_ONCE(*X);
}
exists (1:dynticks=2 /\ 1:x=0)
Running "herd7 -conf linux-kernel.cfg dynticks-into-idle.litmus" verifies
this transition, namely, showing that if the RCU grace-period kthread
(P1) sees another CPU as newly idle (P0), then any pre-idle memory access
(P0's write to X) will be seen by any code following the grace period
(P1's read from X). This is a simple release-acquire pair forcing
ordering in a message-passing (MP) litmus test.
Of course, if the grace-period kthread detects the CPU as non-idle,
it will refrain from reporting a quiescent state on behalf of that CPU,
so there are no ordering requirements from the grace-period kthread in
that case. However, other subsystems call rcu_is_idle_cpu() to check
for CPUs being non-idle from an RCU perspective. That case is also
verified by the above litmus tests with the proviso that the sense of
the low-order bit of the DYNTICKS counter be inverted.
Unfortunately, on x86 smp_mb() is as expensive as a cache-local atomic
increment. This commit therefore weakens only the read from ->dynticks.
However, the updates are abstracted into a rcu_dynticks_inc() function
to ease any future changes that might be needed.
[ paulmck: Apply Linus Torvalds feedback. ]
Link: https://lore.kernel.org/lkml/20210721202127.2129660-4-paulmck@kernel.org/
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
At CPU offline time, we must handle any pending wakeup for the nocb_gp
kthread linked to the outgoing CPU.
Now we are making sure of that twice:
1) From rcu_report_dead() when the outgoing CPU makes the very last
local cleanups by itself before switching offline.
2) From rcutree_dead_cpu(). Here the offlining CPU has gone and is truly
now offline. Another CPU takes care of post-portem cleaning up and
check if the offline CPU had pending wakeup.
Both ways are fine but we have to choose one or the other because we
don't need to repeat that action. Simply benefit from cache locality
and keep only the first solution.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The kernel/rcu/tree_plugin.h file contains not only the plugins for
preemptible RCU, but also many other features including rcu_nocbs
callback offloading. This offloading has become large and complex,
so it is time to put it in its own file.
This commit starts that process.
Suggested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
[ paulmck: Rename to tree_nocb.h, add Frederic as author. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Pull RCU updates from Paul McKenney:
- Bitmap parsing support for "all" as an alias for all bits
- Documentation updates
- Miscellaneous fixes, including some that overlap into mm and lockdep
- kvfree_rcu() updates
- mem_dump_obj() updates, with acks from one of the slab-allocator
maintainers
- RCU NOCB CPU updates, including limited deoffloading
- SRCU updates
- Tasks-RCU updates
- Torture-test updates
* 'core-rcu-2021.07.04' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (78 commits)
tasks-rcu: Make show_rcu_tasks_gp_kthreads() be static inline
rcu-tasks: Make ksoftirqd provide RCU Tasks quiescent states
rcu: Add missing __releases() annotation
rcu: Remove obsolete rcu_read_unlock() deadlock commentary
rcu: Improve comments describing RCU read-side critical sections
rcu: Create an unrcu_pointer() to remove __rcu from a pointer
srcu: Early test SRCU polling start
rcu: Fix various typos in comments
rcu/nocb: Unify timers
rcu/nocb: Prepare for fine-grained deferred wakeup
rcu/nocb: Only cancel nocb timer if not polling
rcu/nocb: Delete bypass_timer upon nocb_gp wakeup
rcu/nocb: Cancel nocb_timer upon nocb_gp wakeup
rcu/nocb: Allow de-offloading rdp leader
rcu/nocb: Directly call __wake_nocb_gp() from bypass timer
rcu: Don't penalize priority boosting when there is nothing to boost
rcu: Point to documentation of ordering guarantees
rcu: Make rcu_gp_cleanup() be noinline for tracing
rcu: Restrict RCU_STRICT_GRACE_PERIOD to at most four CPUs
rcu: Make show_rcu_gp_kthreads() dump rcu_node structures blocking GP
...
Heavy networking load can cause a CPU to execute continuously and
indefinitely within ksoftirqd, in which case there will be no voluntary
task switches and thus no RCU-tasks quiescent states. This commit
therefore causes the exiting rcu_softirq_qs() to provide an RCU-tasks
quiescent state.
This of course means that __do_softirq() and its callers cannot be
invoked from within a tracing trampoline.
Reported-by: Toke Høiland-Jørgensen <toke@redhat.com>
Tested-by: Toke Høiland-Jørgensen <toke@redhat.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
There are a number of places that call out the fact that preempt-disable
regions of code now act as RCU read-side critical sections, where
preempt-disable regions of code include irq-disable regions of code,
bh-disable regions of code, hardirq handlers, and NMI handlers. However,
someone relying solely on (for example) the call_rcu() header comment
might well have no idea that preempt-disable regions of code have RCU
semantics.
This commit therefore updates the header comments for
call_rcu(), synchronize_rcu(), rcu_dereference_bh_check(), and
rcu_dereference_sched_check() to call out these new(ish) forms of RCU
readers.
Reported-by: Michel Lespinasse <michel@lespinasse.org>
[ paulmck: Apply Matthew Wilcox and Michel Lespinasse feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Fix ~12 single-word typos in RCU code comments.
[ paulmck: Apply feedback from Randy Dunlap. ]
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Tuning the deferred wakeup level must be done from a safe wakeup
point. Currently those sites are:
* ->nocb_timer
* user/idle/guest entry
* CPU down
* softirq/rcuc
All of these sites perform the wake up for both RCU_NOCB_WAKE and
RCU_NOCB_WAKE_FORCE.
In order to merge ->nocb_timer and ->nocb_bypass_timer together, we plan
to add a new RCU_NOCB_WAKE_BYPASS that really should be deferred until
a timer fires so that we don't wake up the NOCB-gp kthread too early.
To prepare for that, this commit specifies the per-callsite wakeup
level/limit.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
[ paulmck: Fix non-NOCB rcu_nocb_need_deferred_wakeup() definition. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Add comments to synchronize_rcu() and friends that point to
Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.rst.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Although there are trace events for RCU grace periods, these are only
enabled in CONFIG_RCU_TRACE=y kernels. This commit therefore marks
rcu_gp_cleanup() noinline in order to provide a function that can be
traced that is invoked near the end of each grace period.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
When any CPU comes online, it checks to see if an RCU-boost kthread has
already been created for that CPU's leaf rcu_node structure, and if
not, it creates one. Unfortunately, it also verifies that this leaf
rcu_node structure actually has at least one online CPU, and if not,
it declines to create the kthread. Although this behavior makes sense
during early boot, especially on systems that claim far more CPUs than
they actually have, it makes no sense for the first CPU to come online
for a given rcu_node structure. There is no point in checking because
we know there is a CPU on its way in.
The problem is that timing differences can cause this incoming CPU to not
yet be reflected in the various bit masks even at rcutree_online_cpu()
time, and there is no chance at rcutree_prepare_cpu() time. Plus it
would be better to create the RCU-boost kthread at rcutree_prepare_cpu()
to handle the case where the CPU is involved in an RCU priority inversion
very shortly after it comes online.
This commit therefore moves the checking to rcu_prepare_kthreads(), which
is called only at early boot, when the check is appropriate. In addition,
it makes rcutree_prepare_cpu() invoke rcu_spawn_one_boost_kthread(), which
no longer does any checking for online CPUs.
With this change, RCU priority boosting tests now pass for short rcutorture
runs, even with single-CPU leaf rcu_node structures.
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Scott Wood <swood@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently, rcu_spawn_core_kthreads() is invoked via an early_initcall(),
which works, except that rcu_spawn_gp_kthread() is also invoked via an
early_initcall() and rcu_spawn_core_kthreads() relies on adjustments to
kthread_prio that are carried out by rcu_spawn_gp_kthread(). There is
no guaranttee of ordering among early_initcall() handlers, and thus no
guarantee that kthread_prio will be properly checked and range-limited
at the time that rcu_spawn_core_kthreads() needs it.
In most cases, this bug is harmless. After all, the only reason that
rcu_spawn_gp_kthread() adjusts the value of kthread_prio is if the user
specified a nonsensical value for this boot parameter, which experience
indicates is rare.
Nevertheless, a bug is a bug. This commit therefore causes the
rcu_spawn_core_kthreads() function to be invoked directly from
rcu_spawn_gp_kthread() after any needed adjustments to kthread_prio have
been carried out.
Fixes: 48d07c04b4 ("rcu: Enable elimination of Tree-RCU softirq processing")
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit cleans up some comments and code in kernel/rcu/tree.c.
Signed-off-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Commit 9ee01e0f69 ("x86/entry: Clean up idtentry_enter/exit()
leftovers") left the rcu_irq_exit_preempt() in place in order to avoid
conflicts with the -rcu tree. Now that this change has long since hit
mainline, this commit removes the no-longer-used rcu_irq_exit_preempt()
function.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
An srcu_struct structure that is initialized before rcu_init_geometry()
will have its srcu_node hierarchy based on CONFIG_NR_CPUS. Once
rcu_init_geometry() is called, this hierarchy is compressed as needed
for the actual maximum number of CPUs for this system.
Later on, that srcu_struct structure is confused, sometimes referring
to its initial CONFIG_NR_CPUS-based hierarchy, and sometimes instead
to the new num_possible_cpus() hierarchy. For example, each of its
->mynode fields continues to reference the original leaf rcu_node
structures, some of which might no longer exist. On the other hand,
srcu_for_each_node_breadth_first() traverses to the new node hierarchy.
There are at least two bad possible outcomes to this:
1) a) A callback enqueued early on an srcu_data structure (call it
*sdp) is recorded pending on sdp->mynode->srcu_data_have_cbs in
srcu_funnel_gp_start() with sdp->mynode pointing to a deep leaf
(say 3 levels).
b) The grace period ends after rcu_init_geometry() shrinks the
nodes level to a single one. srcu_gp_end() walks through the new
srcu_node hierarchy without ever reaching the old leaves so the
callback is never executed.
This is easily reproduced on an 8 CPUs machine with CONFIG_NR_CPUS >= 32
and "rcupdate.rcu_self_test=1". The srcu_barrier() after early tests
verification never completes and the boot hangs:
[ 5413.141029] INFO: task swapper/0:1 blocked for more than 4915 seconds.
[ 5413.147564] Not tainted 5.12.0-rc4+ #28
[ 5413.151927] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 5413.159753] task:swapper/0 state:D stack: 0 pid: 1 ppid: 0 flags:0x00004000
[ 5413.168099] Call Trace:
[ 5413.170555] __schedule+0x36c/0x930
[ 5413.174057] ? wait_for_completion+0x88/0x110
[ 5413.178423] schedule+0x46/0xf0
[ 5413.181575] schedule_timeout+0x284/0x380
[ 5413.185591] ? wait_for_completion+0x88/0x110
[ 5413.189957] ? mark_held_locks+0x61/0x80
[ 5413.193882] ? mark_held_locks+0x61/0x80
[ 5413.197809] ? _raw_spin_unlock_irq+0x24/0x50
[ 5413.202173] ? wait_for_completion+0x88/0x110
[ 5413.206535] wait_for_completion+0xb4/0x110
[ 5413.210724] ? srcu_torture_stats_print+0x110/0x110
[ 5413.215610] srcu_barrier+0x187/0x200
[ 5413.219277] ? rcu_tasks_verify_self_tests+0x50/0x50
[ 5413.224244] ? rdinit_setup+0x2b/0x2b
[ 5413.227907] rcu_verify_early_boot_tests+0x2d/0x40
[ 5413.232700] do_one_initcall+0x63/0x310
[ 5413.236541] ? rdinit_setup+0x2b/0x2b
[ 5413.240207] ? rcu_read_lock_sched_held+0x52/0x80
[ 5413.244912] kernel_init_freeable+0x253/0x28f
[ 5413.249273] ? rest_init+0x250/0x250
[ 5413.252846] kernel_init+0xa/0x110
[ 5413.256257] ret_from_fork+0x22/0x30
2) An srcu_struct structure that is initialized before rcu_init_geometry()
and used afterward will always have stale rdp->mynode references,
resulting in callbacks to be missed in srcu_gp_end(), just like in
the previous scenario.
This commit therefore causes init_srcu_struct_nodes to initialize the
geometry, if needed. This ensures that the srcu_node hierarchy is
properly built and distributed from the get-go.
Suggested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Uladzislau Rezki <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Once srcu_init() is called, the SRCU core will make use of delayed
workqueues, which rely on timers. However init_timers() is called
several steps after rcu_init(). This means that a call_srcu() after
rcu_init() but before init_timers() would find itself within a dangerously
uninitialized timer core.
This commit therefore creates a separate call to srcu_init() after
init_timer() completes, which ensures that we stay in early SRCU mode
until timers are safe(r).
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently we have three functions which depend on each other.
Two of them are quite tiny and the last one where the most
work is done. All of them are related to queuing RCU batches
to reclaim objects after a GP.
1. kfree_rcu_monitor(). It consist of few lines. It acquires a spin-lock
and calls kfree_rcu_drain_unlock().
2. kfree_rcu_drain_unlock(). It also consists of few lines of code. It
calls queue_kfree_rcu_work() to queue the batch. If this fails,
it rearms the monitor work to try again later.
3. queue_kfree_rcu_work(). This provides the bulk of the functionality,
attempting to start a new batch to free objects after a GP.
Since there are no external users of functions [2] and [3], both
can eliminated by moving all logic directly into [1], which both
shrinks and simplifies the code.
Also replace comments which start with "/*" to "//" format to make it
unified across the file.
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The kvfree_rcu() function now defers allocations in the common
case due to the fact that there is no lockless access to the
memory-allocator caches/pools. In addition, in CONFIG_PREEMPT_NONE=y
and in CONFIG_PREEMPT_VOLUNTARY=y kernels, there is no reliable way to
determine if spinlocks are held. As a result, allocation is deferred in
the common case, and the two-argument form of kvfree_rcu() thus uses the
"channel 3" queue through all the rcu_head structures. This channel
is called referred to as the emergency case in comments, and these
comments are now obsolete.
This commit therefore updates these comments to reflect the new
common-case nature of such emergencies.
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Replace an open-coded version of the kfree_rcu_monitor() function body
with a call to that function.
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Before attempting to start a new batch the "monitor_todo" variable is
set to "false" and set back to "true" when a previous RCU batch is still
in progress. This is at best confusing.
Thus change this variable to "false" only when a new batch has been
successfully queued, otherwise, just leave it be.
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The rcu_scheduler_active flag is set to RCU_SCHEDULER_RUNNING once the
scheduler is up and running. That signal is used in order to check
and queue a "monitor work" to reclaim freed objects (if there are any)
during early boot. This flag is used by kvfree_rcu() to determine when
work can safely be queued, at which point memory passed to earlier
invocations of kvfree_rcu() can be processed.
However, only "krcp->head" is checked for objects that need to be
released, and there are now two more, namely, "krcp->bkvhead[0]" and
"krcp->bkvhead[1]". Therefore, check these two additional channels.
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
nr_bkv_objs is a count of the objects in the kvfree_rcu page cache.
Accessing it requires holding the ->lock. Switch to READ_ONCE() and
WRITE_ONCE() macros to provide lockless access to this counter.
This lockless access is used for the shrinker.
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Add a drain_page_cache() function to drain a per-cpu page cache.
The reason behind of it is a system can run into a low memory
condition, in that case a page shrinker can ask for its users
to free their caches in order to get extra memory available for
other needs in a system.
When a system hits such condition, a page cache is drained for
all CPUs in a system. By default a page cache work is delayed
with 5 seconds interval until a memory pressure disappears, if
needed it can be changed. See a rcu_delay_page_cache_fill_msec
module parameter.
Co-developed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Zqiang <qiang.zhang@windriver.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
There is a need for a non-blocking polling interface for RCU grace
periods, so this commit supplies start_poll_synchronize_rcu() and
poll_state_synchronize_rcu() for this purpose. Note that the existing
get_state_synchronize_rcu() may be used if future grace periods are
inevitable (perhaps due to a later call_rcu() invocation). The new
start_poll_synchronize_rcu() is to be used if future grace periods
might not otherwise happen. Finally, poll_state_synchronize_rcu()
provides a lockless check for a grace period having elapsed since
the corresponding call to either of the get_state_synchronize_rcu()
or start_poll_synchronize_rcu().
As with get_state_synchronize_rcu(), the return value from either
get_state_synchronize_rcu() or start_poll_synchronize_rcu() is passed in
to a later call to either poll_state_synchronize_rcu() or the existing
(might_sleep) cond_synchronize_rcu().
[ paulmck: Remove redundant smp_mb() per Frederic Weisbecker feedback. ]
[ Update poll_state_synchronize_rcu() docbook per Frederic Weisbecker feedback. ]
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
At the start of a CPU-hotplug operation, the incoming CPU's callback
list can be in a number of states:
1. Disabled and empty. This is the case when the boot CPU has
not invoked call_rcu(), when a non-boot CPU first comes online,
and when a non-offloaded CPU comes back online. In this case,
it is both necessary and permissible to initialize ->cblist.
Because either the CPU is currently running with interrupts
disabled (boot CPU) or is not yet running at all (other CPUs),
it is not necessary to acquire ->nocb_lock.
In this case, initialization is required.
2. Disabled and non-empty. This cannot occur, because early boot
call_rcu() invocations enable the callback list before enqueuing
their callback.
3. Enabled, whether empty or not. In this case, the callback
list has already been initialized. This case occurs when the
boot CPU has executed an early boot call_rcu() and also when
an offloaded CPU comes back online. In both cases, there is
no need to initialize the callback list: In the boot-CPU case,
the CPU has not (yet) gone offline, and in the offloaded case,
the rcuo kthreads are taking care of business.
Because it is not necessary to initialize the callback list,
it is also not necessary to acquire ->nocb_lock.
Therefore, checking if the segcblist is enabled suffices. This commit
therefore initializes the callback list at rcutree_prepare_cpu() time
only if that list is disabled.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
It makes no sense to de-offload an offline CPU because that CPU will never
invoke any remaining callbacks. It also makes little sense to offload an
offline CPU because any pending RCU callbacks were migrated when that CPU
went offline. Yes, it is in theory possible to use a number of tricks
to permit offloading and deoffloading offline CPUs in certain cases, but
in practice it is far better to have the simple and deterministic rule
"Toggling the offload state of an offline CPU is forbidden".
For but one example, consider that an offloaded offline CPU might have
millions of callbacks queued. Best to just say "no".
This commit therefore forbids toggling of the offloaded state of
offline CPUs.
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Provide CONFIG_PROVE_RCU sanity checks to ensure we are always reading
the offloaded state of an rdp in a safe and stable way and prevent from
its value to be changed under us. We must either hold the barrier mutex,
the cpu-hotplug lock (read or write) or the nocb lock.
Local non-preemptible reads are also safe. NOCB kthreads and timers have
their own means of synchronization against the offloaded state updaters.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Running an rcuscale stress-suite can lead to "Out of memory" of a
system. This can happen under high memory pressure with a small amount
of physical memory.
For example, a KVM test configuration with 64 CPUs and 512 megabytes
can result in OOM when running rcuscale with below parameters:
../kvm.sh --torture rcuscale --allcpus --duration 10 --kconfig CONFIG_NR_CPUS=64 \
--bootargs "rcuscale.kfree_rcu_test=1 rcuscale.kfree_nthreads=16 rcuscale.holdoff=20 \
rcuscale.kfree_loops=10000 torture.disable_onoff_at_boot" --trust-make
<snip>
[ 12.054448] kworker/1:1H invoked oom-killer: gfp_mask=0x2cc0(GFP_KERNEL|__GFP_NOWARN), order=0, oom_score_adj=0
[ 12.055303] CPU: 1 PID: 377 Comm: kworker/1:1H Not tainted 5.11.0-rc3+ #510
[ 12.055416] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.12.0-1 04/01/2014
[ 12.056485] Workqueue: events_highpri fill_page_cache_func
[ 12.056485] Call Trace:
[ 12.056485] dump_stack+0x57/0x6a
[ 12.056485] dump_header+0x4c/0x30a
[ 12.056485] ? del_timer_sync+0x20/0x30
[ 12.056485] out_of_memory.cold.47+0xa/0x7e
[ 12.056485] __alloc_pages_slowpath.constprop.123+0x82f/0xc00
[ 12.056485] __alloc_pages_nodemask+0x289/0x2c0
[ 12.056485] __get_free_pages+0x8/0x30
[ 12.056485] fill_page_cache_func+0x39/0xb0
[ 12.056485] process_one_work+0x1ed/0x3b0
[ 12.056485] ? process_one_work+0x3b0/0x3b0
[ 12.060485] worker_thread+0x28/0x3c0
[ 12.060485] ? process_one_work+0x3b0/0x3b0
[ 12.060485] kthread+0x138/0x160
[ 12.060485] ? kthread_park+0x80/0x80
[ 12.060485] ret_from_fork+0x22/0x30
[ 12.062156] Mem-Info:
[ 12.062350] active_anon:0 inactive_anon:0 isolated_anon:0
[ 12.062350] active_file:0 inactive_file:0 isolated_file:0
[ 12.062350] unevictable:0 dirty:0 writeback:0
[ 12.062350] slab_reclaimable:2797 slab_unreclaimable:80920
[ 12.062350] mapped:1 shmem:2 pagetables:8 bounce:0
[ 12.062350] free:10488 free_pcp:1227 free_cma:0
...
[ 12.101610] Out of memory and no killable processes...
[ 12.102042] Kernel panic - not syncing: System is deadlocked on memory
[ 12.102583] CPU: 1 PID: 377 Comm: kworker/1:1H Not tainted 5.11.0-rc3+ #510
[ 12.102600] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.12.0-1 04/01/2014
<snip>
Because kvfree_rcu() has a fallback path, memory allocation failure is
not the end of the world. Furthermore, the added overhead of aggressive
GFP settings must be balanced against the overhead of the fallback path,
which is a cache miss for double-argument kvfree_rcu() and a call to
synchronize_rcu() for single-argument kvfree_rcu(). The current choice
of GFP_KERNEL|__GFP_NOWARN can result in longer latencies than a call
to synchronize_rcu(), so less-tenacious GFP flags would be helpful.
Here is the tradeoff that must be balanced:
a) Minimize use of the fallback path,
b) Avoid pushing the system into OOM,
c) Bound allocation latency to that of synchronize_rcu(), and
d) Leave the emergency reserves to use cases lacking fallbacks.
This commit therefore changes GFP flags from GFP_KERNEL|__GFP_NOWARN to
GFP_KERNEL|__GFP_NORETRY|__GFP_NOMEMALLOC|__GFP_NOWARN. This combination
leaves the emergency reserves alone and can initiate reclaim, but will
not invoke the OOM killer.
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
__GFP_RETRY_MAYFAIL can spend quite a bit of time reclaiming, and this
can be wasted effort given that there is a fallback code path in case
memory allocation fails.
__GFP_NORETRY does perform some light-weight reclaim, but it will fail
under OOM conditions, allowing the fallback to be taken as an alternative
to hard-OOMing the system.
There is a four-way tradeoff that must be balanced:
1) Minimize use of the fallback path;
2) Avoid full-up OOM;
3) Do a light-wait allocation request;
4) Avoid dipping into the emergency reserves.
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The krc_this_cpu_unlock() function does a raw_spin_unlock() immediately
followed by a local_irq_restore(). This commit saves a line of code by
merging them into a raw_spin_unlock_irqrestore(). This transformation
also reduces scheduling latency because raw_spin_unlock_irqrestore()
responds immediately to a reschedule request. In contrast,
local_irq_restore() does a scheduling-oblivious enabling of interrupts.
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit applies the __GFP_NOMEMALLOC gfp flag to memory allocations
carried out by the single-argument variant of kvfree_rcu(), thus avoiding
this can-sleep code path from dipping into the emergency reserves.
Acked-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Single-argument kvfree_rcu() must be invoked from sleepable contexts,
so we can directly allocate pages. Furthermmore, the fallback in case
of page-allocation failure is the high-latency synchronize_rcu(), so it
makes sense to do these page allocations from the fastpath, and even to
permit limited sleeping within the allocator.
This commit therefore allocates if needed on the fastpath using
GFP_KERNEL|__GFP_RETRY_MAYFAIL. This also has the beneficial effect
of leaving kvfree_rcu()'s per-CPU caches to the double-argument variant
of kvfree_rcu(), given that the double-argument variant cannot directly
invoke the allocator.
[ paulmck: Add add_ptr_to_bulk_krc_lock header comment per Michal Hocko. ]
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
In rcu_nmi_enter(), there is an erroneous instrumentation_end() in the
second branch of the "if" statement. Oddly enough, "objtool check -f
vmlinux.o" fails to complain because it is unable to correctly cover
all cases. Instead, objtool visits the third branch first, which marks
following trace_rcu_dyntick() as visited. This commit therefore removes
the spurious instrumentation_end().
Fixes: 04b25a495b ("rcu: Mark rcu_nmi_enter() call to rcu_cleanup_after_idle() noinstr")
Reported-by Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
