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Signed-off-by: Russell Harmon <eatnumber1@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Signed-off-by: Russell Harmon <eatnumber1@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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"Buffers" are buffers of the metadata/checksum area of dm-integrity.
They are always at most as large as a single metadata area on-disk, but
may be smaller.
Signed-off-by: Russell Harmon <eatnumber1@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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"where dm-integrity uses bitmap" becomes "where dm-integrity uses a
bitmap"
Signed-off-by: Russell Harmon <eatnumber1@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Hello,
This patch is to expose misc.current on cgroup v2 root for tracking
how much of the resource has been consumed in total on the system.
Most of the cloud infrastucture use cgroup to fetch the host
information for scheduling purpose.
Currently, the misc controller can be used by Intel TDX HKIDs and
AMD SEV ASIDs, which are both used for creating encrypted VMs.
Intel TDX and AMD SEV are mostly be used by the cloud providers
for providing confidential VMs.
In actual use of a server, these confidential VMs may be launched
in different ways. For the cloud solution, there are kubvirt and
coco (tracked by kubepods.slice); on host, they can be booted
directly through qemu by end user (tracked by user.slice), etc.
In this complex environment, when wanting to know how many resource
is used in total it has to iterate through all existing slices to
get the value of each misc.current and add them up to calculate
the total number of consumed keys.
So exposing misc.current to root cgroup tends to give much easier
when calculates how much resource has been used in total, which
helps to schedule and count resources for the cloud infrastucture.
Signed-off-by: LeiZhou-97 <lei.zhou@intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Architecture-specific documentation is being moved into Documentation/arch/
as a way of cleaning up the top-level documentation directory and making
the docs hierarchy more closely match the source hierarchy. Move
Documentation/arm64 into arch/ (along with the Chinese equvalent
translations) and fix up documentation references.
Cc: Will Deacon <will@kernel.org>
Cc: Alex Shi <alexs@kernel.org>
Cc: Hu Haowen <src.res@email.cn>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Yantengsi <siyanteng@loongson.cn>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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The recommended ways for getting DAMON monitoring results are using
tried_regions sysfs directory for partial snapshot of the results, and
DAMON tracepoint for full record of the results. However, the
tried_regions sysfs directory usage has not sufficiently updated on some
sections of the DAMON usage document. Update those.
Link: https://lkml.kernel.org/r/20230616191742.87531-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Explanation of DAMOS quotas and watermarks are not clearly explaining the
meaning and expectation of each file. Add more clarification for those.
Link: https://lkml.kernel.org/r/20230616191742.87531-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The background and concept of DAMOS is redundantly documented, in the
design document and the usage document. Replace the duplicated ones in
usage document with links to the design document.
Link: https://lkml.kernel.org/r/20230616191742.87531-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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supported address spaces
Brief explanation of DAMON user space tool and sysfs interface are
unnecessarily and repeatedly mentioning the list of address spaces that
DAMON is supporting. Remove those.
Link: https://lkml.kernel.org/r/20230616191742.87531-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Fix typos including a unnecessary comma and incomplete ':ref:' keywords.
Link: https://lkml.kernel.org/r/20230616191742.87531-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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DAMON user-space tool, damo, has deprecated[1] its old DAMOS schemes
specification format. However, an example of DAMON documentation is still
using it. Update the example to use one of the alternative options.
[1] https://github.com/awslabs/damo/commit/e9950ae68f6c
Link: https://lkml.kernel.org/r/20230616191742.87531-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Since commit c7c3dec1c9db ("mm: rmap: remove lock_page_memcg()"),
no more user, kill lock_page_memcg() and unlock_page_memcg().
Link: https://lkml.kernel.org/r/20230614143612.62575-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Building the 'htmldocs' target results in the following warning when
processing 'hisi-pmu.rst':
| Documentation/admin-guide/perf/hisi-pmu.rst:107: ERROR: Unexpected indentation.
Fix the warning by converting all of the register bitfield lists into
proper bulleted lists and adjusting the indentation of the wrapping line
accordingly. At the same time, use an enumerated list to describe the
new PMUv2 functions.
Fixes: ea8d1c062a0e ("docs: perf: Add new description for HiSilicon UC PMU")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Will Deacon <will@kernel.org>
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'core' and 'x86/amd' into next
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The random_read_corrupt and random_write_corrupt options corrupt a
random byte in a bio with the provided probability. The corruption
only happens in the "down" interval.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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A new function is added on HiSilicon uncore UC PMU.
The UC PMU support to filter statistical information based on
the specified tx request uring channel. Make user configuration
through "uring_channel" parameter.
Document them to provide guidance on how to use them.
Signed-off-by: Junhao He <hejunhao3@huawei.com>
Reviewed-by: Jonathan Cameron <Jonthan.Cameron@huawei.com>
Reviewed-by: Yicong Yang <yangyicong@hisilicon.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20230615125926.29832-4-hejunhao3@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>
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Cross-merge networking fixes after downstream PR.
Conflicts:
include/linux/mlx5/driver.h
617f5db1a626 ("RDMA/mlx5: Fix affinity assignment")
dc13180824b7 ("net/mlx5: Enable devlink port for embedded cpu VF vports")
https://lore.kernel.org/all/20230613125939.595e50b8@canb.auug.org.au/
tools/testing/selftests/net/mptcp/mptcp_join.sh
47867f0a7e83 ("selftests: mptcp: join: skip check if MIB counter not supported")
425ba803124b ("selftests: mptcp: join: support RM_ADDR for used endpoints or not")
45b1a1227a7a ("mptcp: introduces more address related mibs")
0639fa230a21 ("selftests: mptcp: add explicit check for new mibs")
https://lore.kernel.org/netdev/20230609-upstream-net-20230610-mptcp-selftests-support-old-kernels-part-3-v1-0-2896fe2ee8a3@tessares.net/
No adjacent changes.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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The cache_readaheads stat counter is not used anymore and should be
removed.
Signed-off-by: Andrea Tomassetti <andrea.tomassetti-opensource@devo.com>
Signed-off-by: Coly Li <colyli@suse.de>
Link: https://lore.kernel.org/r/20230615121223.22502-4-colyli@suse.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This patch is similar to commit 8e20d4b33266 ("mm/memcontrol: export
memcg->watermark via sysfs for v2 memcg"), but exports the swap counter's
watermark.
We allocate jobs to our compute farm using heuristics determined by memory
and swap usage from previous jobs. Tracking the peak swap usage for new
jobs is important for determining when jobs are exceeding their expected
bounds, or when our baseline metrics are getting outdated.
Our toolset was written to use the "memory.memsw.max_usage_in_bytes" file
in cgroups v1, and altering it to poll cgroups v2's "memory.swap.current"
would give less accurate results as well as add complication to the code.
Having this watermark exposed in sysfs is much preferred.
Link: https://lkml.kernel.org/r/20230524181734.125696-1-lars@pixar.com
Signed-off-by: Lars R. Damerow <lars@pixar.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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An Interrupt Remapping Table (IRT) stores interrupt remapping configuration
for each device. In a normal operation, the AMD IOMMU caches the table
to optimize subsequent data accesses. This requires the IOMMU driver to
invalidate IRT whenever it updates the table. The invalidation process
includes issuing an INVALIDATE_INTERRUPT_TABLE command following by
a COMPLETION_WAIT command.
However, there are cases in which the IRT is updated at a high rate.
For example, for IOMMU AVIC, the IRTE[IsRun] bit is updated on every
vcpu scheduling (i.e. amd_iommu_update_ga()). On system with large
amount of vcpus and VFIO PCI pass-through devices, the invalidation
process could potentially become a performance bottleneck.
Introducing a new kernel boot option:
amd_iommu=irtcachedis
which disables IRTE caching by setting the IRTCachedis bit in each IOMMU
Control register, and bypass the IRT invalidation process.
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Co-developed-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Link: https://lore.kernel.org/r/20230530141137.14376-4-suravee.suthikulpanit@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
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Linux 6.4-rc5
* tag 'v6.4-rc5': (919 commits)
Linux 6.4-rc5
leds: qcom-lpg: Fix PWM period limits
selftests/ftrace: Choose target function for filter test from samples
KVM: selftests: Add test for race in kvm_recalculate_apic_map()
KVM: x86: Bail from kvm_recalculate_phys_map() if x2APIC ID is out-of-bounds
KVM: x86: Account fastpath-only VM-Exits in vCPU stats
KVM: SVM: vNMI pending bit is V_NMI_PENDING_MASK not V_NMI_BLOCKING_MASK
KVM: x86/mmu: Grab memslot for correct address space in NX recovery worker
tpm, tpm_tis: correct tpm_tis_flags enumeration values
Revert "ext4: remove ac->ac_found > sbi->s_mb_min_to_scan dead check in ext4_mb_check_limits"
media: uvcvideo: Don't expose unsupported formats to userspace
media: v4l2-subdev: Fix missing kerneldoc for client_caps
media: staging: media: imx: initialize hs_settle to avoid warning
media: v4l2-mc: Drop subdev check in v4l2_create_fwnode_links_to_pad()
riscv: Implement missing huge_ptep_get
riscv: Fix huge_ptep_set_wrprotect when PTE is a NAPOT
module/decompress: Fix error checking on zstd decompression
fork, vhost: Use CLONE_THREAD to fix freezer/ps regression
dt-bindings: serial: 8250_omap: add rs485-rts-active-high
selinux: don't use make's grouped targets feature yet
...
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hlt,nohlt paramaters are useful when debugging cpuidle
related issues.
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
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Provide a generic smt parameters interface aligned with s390
to allow users to limit smt usage and threads per core.
It replaced previous undocumented "nothreads" parameter for
smp-cps which is ambiguous and does not cover smp-mt.
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
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git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
- Fix css_set reference leaks on fork failures
- Fix CPU hotplug locking in cgroup_transfer_tasks() which is used by
cgroup1 cpuset
- Doc update
* tag 'cgroup-for-6.4-rc5-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: Documentation: Clarify usage of memory limits
cgroup: always put cset in cgroup_css_set_put_fork
cgroup: fix missing cpus_read_{lock,unlock}() in cgroup_transfer_tasks()
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'nocb.2023.05.11a', 'rcu-tasks.2023.05.10a', 'torture.2023.05.15a' and 'rcu-urgent.2023.06.06a' into HEAD
doc.2023.05.10a: Documentation updates
fixes.2023.05.11a: Miscellaneous fixes
kvfree.2023.05.10a: kvfree_rcu updates
nocb.2023.05.11a: Callback-offloading updates
rcu-tasks.2023.05.10a: Tasks RCU updates
torture.2023.05.15a: Torture-test updates
rcu-urgent.2023.06.06a: Urgent SRCU fix
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Since commit a78418e6a04c ("block: Always initialize bio IO priority on
submit"), bio->bi_ioprio will never be IOPRIO_CLASS_NONE when calling
blkcg_set_ioprio(), so there will be no way to promote the io-priority
of one cgroup to IOPRIO_CLASS_RT, because bi_ioprio will always be
greater than or equals to IOPRIO_CLASS_RT.
It seems possible to call blkcg_set_ioprio() first then try to
initialize bi_ioprio later in bio_set_ioprio(), but this doesn't work
for bio in which bi_ioprio is already initialized (e.g., direct-io), so
introduce a new promote-to-rt policy to promote the iopriority of bio to
IOPRIO_CLASS_RT if the ioprio is not already RT.
For none-to-rt policy, although it doesn't work now, but considering
that its purpose was also to override the io-priority to RT and allowing
for a smoother transition, just keep it and treat it as an alias of
the promote-to-rt policy.
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Link: https://lore.kernel.org/r/20230428074404.280532-1-houtao@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The existing documentation refers to memory.high as the "main mechanism
to control memory usage." This seems incorrect to me - memory.high can
result in reclaim pressure which simply leads to stalls unless some
external component observes and actions on it (e.g. systemd-oomd can be
used for this purpose). While this is feasible, users are unaware of
this interaction and are led to believe that memory.high alone is an
effective mechanism for limiting memory.
The documentation should recommend the use of memory.max as the
effective way to enforce memory limits - it triggers reclaim and results
in OOM kills by itself.
Signed-off-by: Dan Schatzberg <schatzberg.dan@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Chris Down <chris@chrisdown.name>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Create a new block/early-lookup.c to keep the early block device lookup
code instead of having this code sit with the early mount code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230531125535.676098-16-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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name_to_dev_t has a very misleading name, that doesn't make clear
it should only be used by the early init code, and also has a bad
calling convention that doesn't allow returning different kinds of
errors. Rename it to early_lookup_bdev to make the use case clear,
and return an errno, where -EINVAL means the string could not be
parsed, and -ENODEV means it the string was valid, but there was
no device found for it.
Also stub out the whole call for !CONFIG_BLOCK as all the non-block
root cases are always covered in the caller.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230531125535.676098-14-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The nfs/cifs/ram special case only needs to be parsed once, and only in
the boot code. Move them out of name_to_dev_t and into
prepare_namespace.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230531125535.676098-13-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Make it possible to disable the MOPS extension at runtime using the
kernel command line. This can be useful for testing or working around
hardware issues. For example it could be used to test new memory copy
routines that do not use MOPS instructions (e.g. from Arm Optimized
Routines).
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Link: https://lore.kernel.org/r/20230509142235.3284028-11-kristina.martsenko@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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Cross-merge networking fixes after downstream PR.
No conflicts.
Adjacent changes:
drivers/net/ethernet/sfc/tc.c
622ab656344a ("sfc: fix error unwinds in TC offload")
b6583d5e9e94 ("sfc: support TC decap rules matching on enc_src_port")
net/mptcp/protocol.c
5b825727d087 ("mptcp: add annotations around msk->subflow accesses")
e76c8ef5cc5b ("mptcp: refactor mptcp_stream_accept()")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Initialize the ACPI core for RISC-V during boot.
ACPI tables and interpreter are initialized based on
the information passed from the firmware and the value of
the kernel parameter 'acpi'.
With ACPI support added for RISC-V, the kernel parameter 'acpi'
is also supported on RISC-V. Hence, update the documentation.
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230515054928.2079268-9-sunilvl@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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Add a new command line option "mtrr=debug" for getting debug output
after building the new cache mode map. The output will include MTRR
register values and the resulting map.
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20230502120931.20719-13-jgross@suse.com
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
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Cross-merge networking fixes after downstream PR.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Update Rockchip ISP1 driver file path
Signed-off-by: Jack Zhu <jack.zhu@starfivetech.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
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The net.core.txrehash documentation mentions this knob is for listening
sockets only, while sk_rethink_txhash can be called on SYN and RTO
retransmits on all TCP sockets.
Remove the listening socket part.
Signed-off-by: Antoine Tenart <atenart@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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The fs/cifs directory has moved to fs/smb/client, correct mentions
of this in Documentation and comments.
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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The descriptions of certain KVM related kernel parameters can be
confusing. They state "Disable ...," which may make people think that
setting them to 1 will disable the associated feature when in fact the
opposite is true.
This commit addresses this issue by revising the descriptions of these
parameters by using "Control..." rather than "Enable/Disable...".
1==enabled or 0==disabled can be communicated by the description of
default value such as "1 (enabled)" or "0 (disabled)".
Also update the description of KVM's default value for kvm-intel.nested
as it is enabled by default.
Signed-off-by: Yan-Jie Wang <yanjiewtw@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20230503081530.19956-1-yanjiewtw@gmail.com
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Information about intel_pstate active mode is added in the doc.
This operation mode could be used to set on the hardware when it's
not activated. Status of the mode could be checked from sysfs file
i.e., /sys/devices/system/cpu/intel_pstate/status.
The information is already available in cpu-freq/intel-pstate.txt
documentation.
Signed-off-by: Natesh Sharma <nsharma@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
[jc: reformatted for width ]
Link: https://lore.kernel.org/r/20230427083706.49882-1-nsharma@redhat.com
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Workqueue now automatically marks per-cpu work items that hog CPU for too
long as CPU_INTENSIVE, which excludes them from concurrency management and
prevents stalling other concurrency-managed work items. If a work function
keeps running over the thershold, it likely needs to be switched to use an
unbound workqueue.
This patch adds a debug mechanism which tracks the work functions which
trigger the automatic CPU_INTENSIVE mechanism and report them using
pr_warn() with exponential backoff.
v3: Documentation update.
v2: Drop bouncing to kthread_worker for printing messages. It was to avoid
introducing circular locking dependency through printk but not effective
as it still had pool lock -> wci_lock -> printk -> pool lock loop. Let's
just print directly using printk_deferred().
Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
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If a per-cpu work item hogs the CPU, it can prevent other work items from
starting through concurrency management. A per-cpu workqueue which intends
to host such CPU-hogging work items can choose to not participate in
concurrency management by setting %WQ_CPU_INTENSIVE; however, this can be
error-prone and difficult to debug when missed.
This patch adds an automatic CPU usage based detection. If a
concurrency-managed work item consumes more CPU time than the threshold
(10ms by default) continuously without intervening sleeps, wq_worker_tick()
which is called from scheduler_tick() will detect the condition and
automatically mark it CPU_INTENSIVE.
The mechanism isn't foolproof:
* Detection depends on tick hitting the work item. Getting preempted at the
right timings may allow a violating work item to evade detection at least
temporarily.
* nohz_full CPUs may not be running ticks and thus can fail detection.
* Even when detection is working, the 10ms detection delays can add up if
many CPU-hogging work items are queued at the same time.
However, in vast majority of cases, this should be able to detect violations
reliably and provide reasonable protection with a small increase in code
complexity.
If some work items trigger this condition repeatedly, the bigger problem
likely is the CPU being saturated with such per-cpu work items and the
solution would be making them UNBOUND. The next patch will add a debug
mechanism to help spot such cases.
v4: Documentation for workqueue.cpu_intensive_thresh_us added to
kernel-parameters.txt.
v3: Switch to use wq_worker_tick() instead of hooking into preemptions as
suggested by Peter.
v2: Lai pointed out that wq_worker_stopping() also needs to be called from
preemption and rtlock paths and an earlier patch was updated
accordingly. This patch adds a comment describing the risk of infinte
recursions and how they're avoided.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
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* improve the short description of localmodconfig in the step-by-step
guide while fixing its broken first sentence
* briefly mention immutable Linux distributions
* use '--shallow-exclude=v6.0' throughout the document
* instead of "git reset --hard; git checkout ..." use "git checkout
--force ..." in the step-by-step guide: this matches the TLDR and is
one command less to execute. This led to a few small adjustments to
the text and the flow in the surrounding area.
* fix two thinkos in the section explaining full git clones
Signed-off-by: Thorsten Leemhuis <linux@leemhuis.info>
Link: https://lore.kernel.org/r/6f4684b9a5d11d3adb04e0af3cfc60db8b28eeb2.1684140700.git.linux@leemhuis.info
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Sometimes the one-line ORC unwinder warnings aren't very helpful. Add a
new 'unwind_debug' cmdline option which will dump the full stack
contents of the current task when an error condition is encountered.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lore.kernel.org/r/6afb9e48a05fd2046bfad47e69b061b43dfd0e0e.1681331449.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
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If you build a kernel with CONFIG_PREEMPTION=n and CONFIG_PREEMPT_COUNT=y,
then run the rcutorture tests specifying stalls as follows:
runqemu kvm slirp nographic qemuparams="-m 1024 -smp 4" \
bootparams="console=ttyS0 rcutorture.stall_cpu=30 \
rcutorture.stall_no_softlockup=1 rcutorture.stall_cpu_block=1" -d
The tests will produce the following splat:
[ 10.841071] rcu-torture: rcu_torture_stall begin CPU stall
[ 10.841073] rcu_torture_stall start on CPU 3.
[ 10.841077] BUG: scheduling while atomic: rcu_torture_sta/66/0x0000000
....
[ 10.841108] Call Trace:
[ 10.841110] <TASK>
[ 10.841112] dump_stack_lvl+0x64/0xb0
[ 10.841118] dump_stack+0x10/0x20
[ 10.841121] __schedule_bug+0x8b/0xb0
[ 10.841126] __schedule+0x2172/0x2940
[ 10.841157] schedule+0x9b/0x150
[ 10.841160] schedule_timeout+0x2e8/0x4f0
[ 10.841192] schedule_timeout_uninterruptible+0x47/0x50
[ 10.841195] rcu_torture_stall+0x2e8/0x300
[ 10.841199] kthread+0x175/0x1a0
[ 10.841206] ret_from_fork+0x2c/0x50
This is because the rcutorture.stall_cpu_block=1 module parameter causes
rcu_torture_stall() to invoke schedule_timeout_uninterruptible() within
an RCU read-side critical section. This in turn results in a quiescent
state (which prevents the stall) and a sleep in an atomic context (which
produces the above splat).
Although this code is operating as designed, the design has proven to
be counterintuitive to many. This commit therefore updates the description
in kernel-parameters.txt accordingly.
[ paulmck: Apply Joel Fernandes feedback. ]
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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There is often significant latency in the early stages of CPU bringup, and
time is wasted by waking each CPU (e.g. with SIPI/INIT/INIT on x86) and
then waiting for it to respond before moving on to the next.
Allow a platform to enable parallel setup which brings all to be onlined
CPUs up to the CPUHP_BP_KICK_AP state. While this state advancement on the
control CPU (BP) is single-threaded the important part is the last state
CPUHP_BP_KICK_AP which wakes the to be onlined CPUs up.
This allows the CPUs to run up to the first sychronization point
cpuhp_ap_sync_alive() where they wait for the control CPU to release them
one by one for the full onlining procedure.
This parallelism depends on the CPU hotplug core sync mechanism which
ensures that the parallel brought up CPUs wait for release before touching
any state which would make the CPU visible to anything outside the hotplug
control mechanism.
To handle the SMT constraints of X86 correctly the bringup happens in two
iterations when CONFIG_HOTPLUG_SMT is enabled. The control CPU brings up
the primary SMT threads of each core first, which can load the microcode
without the need to rendevouz with the thread siblings. Once that's
completed it brings up the secondary SMT threads.
Co-developed-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com> # Steam Deck
Link: https://lore.kernel.org/r/20230512205257.240231377@linutronix.de
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This was introduced together with commit e1c467e69040 ("x86, hotplug: Wake
up CPU0 via NMI instead of INIT, SIPI, SIPI") to eventually support
physical hotplug of CPU0:
"We'll change this code in the future to wake up hard offlined CPU0 if
real platform and request are available."
11 years later this has not happened and physical hotplug is not officially
supported. Remove the cruft.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com> # Steam Deck
Link: https://lore.kernel.org/r/20230512205255.715707999@linutronix.de
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This commit adds kernel-parameters.txt documentation for the
rcutree.rcu_resched_ns module parameter.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit puts the rcutree module parameters back into proper
alphabetical order.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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