When we free a HugeTLB page to the buddy allocator, we need to allocate
the vmemmap pages associated with it. However, we may not be able to
allocate the vmemmap pages when the system is under memory pressure. In
this case, we just refuse to free the HugeTLB page. This changes behavior
in some corner cases as listed below:
1) Failing to free a huge page triggered by the user (decrease nr_pages).
User needs to try again later.
2) Failing to free a surplus huge page when freed by the application.
Try again later when freeing a huge page next time.
3) Failing to dissolve a free huge page on ZONE_MOVABLE via
offline_pages().
This can happen when we have plenty of ZONE_MOVABLE memory, but
not enough kernel memory to allocate vmemmmap pages. We may even
be able to migrate huge page contents, but will not be able to
dissolve the source huge page. This will prevent an offline
operation and is unfortunate as memory offlining is expected to
succeed on movable zones. Users that depend on memory hotplug
to succeed for movable zones should carefully consider whether the
memory savings gained from this feature are worth the risk of
possibly not being able to offline memory in certain situations.
4) Failing to dissolve a huge page on CMA/ZONE_MOVABLE via
alloc_contig_range() - once we have that handling in place. Mainly
affects CMA and virtio-mem.
Similar to 3). virito-mem will handle migration errors gracefully.
CMA might be able to fallback on other free areas within the CMA
region.
Vmemmap pages are allocated from the page freeing context. In order for
those allocations to be not disruptive (e.g. trigger oom killer)
__GFP_NORETRY is used. hugetlb_lock is dropped for the allocation because
a non sleeping allocation would be too fragile and it could fail too
easily under memory pressure. GFP_ATOMIC or other modes to access memory
reserves is not used because we want to prevent consuming reserves under
heavy hugetlb freeing.
[mike.kravetz@oracle.com: fix dissolve_free_huge_page use of tail/head page]
Link: https://lkml.kernel.org/r/20210527231225.226987-1-mike.kravetz@oracle.com
[willy@infradead.org: fix alloc_vmemmap_page_list documentation warning]
Link: https://lkml.kernel.org/r/20210615200242.1716568-6-willy@infradead.org
Link: https://lkml.kernel.org/r/20210510030027.56044-7-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Barry Song <song.bao.hua@hisilicon.com>
Cc: Bodeddula Balasubramaniam <bodeddub@amazon.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chen Huang <chenhuang5@huawei.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Oliver Neukum <oneukum@suse.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull device mapper updates from Mike Snitzer:
- Various DM persistent-data library improvements and fixes that
benefit both the DM thinp and cache targets.
- A few small DM kcopyd efficiency improvements.
- Significant zoned related block core, DM core and DM zoned target
changes that culminate with adding zoned append emulation (which is
required to properly fix DM crypt's zoned support).
- Various DM writecache target changes that improve efficiency. Adds an
optional "metadata_only" feature that only promotes bios flagged with
REQ_META. But the most significant improvement is writecache's
ability to pause writeback, for a confiurable time, if/when the
working set is larger than the cache (and the cache is full) -- this
ensures performance is no worse than the slower origin device.
* tag 'for-5.14/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (35 commits)
dm writecache: make writeback pause configurable
dm writecache: pause writeback if cache full and origin being written directly
dm io tracker: factor out IO tracker
dm btree remove: assign new_root only when removal succeeds
dm zone: fix dm_revalidate_zones() memory allocation
dm ps io affinity: remove redundant continue statement
dm writecache: add optional "metadata_only" parameter
dm writecache: add "cleaner" and "max_age" to Documentation
dm writecache: write at least 4k when committing
dm writecache: flush origin device when writing and cache is full
dm writecache: have ssd writeback wait if the kcopyd workqueue is busy
dm writecache: use list_move instead of list_del/list_add in writecache_writeback()
dm writecache: commit just one block, not a full page
dm writecache: remove unused gfp_t argument from wc_add_block()
dm crypt: Fix zoned block device support
dm: introduce zone append emulation
dm: rearrange core declarations for extended use from dm-zone.c
block: introduce BIO_ZONE_WRITE_LOCKED bio flag
block: introduce bio zone helpers
block: improve handling of all zones reset operation
...
Merge misc updates from Andrew Morton:
"191 patches.
Subsystems affected by this patch series: kthread, ia64, scripts,
ntfs, squashfs, ocfs2, kernel/watchdog, and mm (gup, pagealloc, slab,
slub, kmemleak, dax, debug, pagecache, gup, swap, memcg, pagemap,
mprotect, bootmem, dma, tracing, vmalloc, kasan, initialization,
pagealloc, and memory-failure)"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (191 commits)
mm,hwpoison: make get_hwpoison_page() call get_any_page()
mm,hwpoison: send SIGBUS with error virutal address
mm/page_alloc: split pcp->high across all online CPUs for cpuless nodes
mm/page_alloc: allow high-order pages to be stored on the per-cpu lists
mm: replace CONFIG_FLAT_NODE_MEM_MAP with CONFIG_FLATMEM
mm: replace CONFIG_NEED_MULTIPLE_NODES with CONFIG_NUMA
docs: remove description of DISCONTIGMEM
arch, mm: remove stale mentions of DISCONIGMEM
mm: remove CONFIG_DISCONTIGMEM
m68k: remove support for DISCONTIGMEM
arc: remove support for DISCONTIGMEM
arc: update comment about HIGHMEM implementation
alpha: remove DISCONTIGMEM and NUMA
mm/page_alloc: move free_the_page
mm/page_alloc: fix counting of managed_pages
mm/page_alloc: improve memmap_pages dbg msg
mm: drop SECTION_SHIFT in code comments
mm/page_alloc: introduce vm.percpu_pagelist_high_fraction
mm/page_alloc: limit the number of pages on PCP lists when reclaim is active
mm/page_alloc: scale the number of pages that are batch freed
...
Pull ACPI updates from Rafael Wysocki:
"These update the ACPICA code in the kernel to the 20210604 upstream
revision, add preliminary support for the Platform Runtime Mechanism
(PRM), address issues related to the handling of device dependencies
in the ACPI device eunmeration code, improve the tracking of ACPI
power resource states, improve the ACPI support for suspend-to-idle on
AMD systems, continue the unification of message printing in the ACPI
code, address assorted issues and clean up the code in a number of
places.
Specifics:
- Update ACPICA code in the kernel to upstrea revision 20210604
including the following changes:
- Add defines for the CXL Host Bridge Structureand and add the
CFMWS structure definition to CEDT (Alison Schofield).
- iASL: Finish support for the IVRS ACPI table (Bob Moore).
- iASL: Add support for the SVKL table (Bob Moore).
- iASL: Add full support for RGRT ACPI table (Bob Moore).
- iASL: Add support for the BDAT ACPI table (Bob Moore).
- iASL: add disassembler support for PRMT (Erik Kaneda).
- Fix memory leak caused by _CID repair function (Erik Kaneda).
- Add support for PlatformRtMechanism OpRegion (Erik Kaneda).
- Add PRMT module header to facilitate parsing (Erik Kaneda).
- Add _PLD panel positions (Fabian Wüthrich).
- MADT: add Multiprocessor Wakeup Mailbox Structure and the SVKL
table headers (Kuppuswamy Sathyanarayanan).
- Use ACPI_FALLTHROUGH (Wei Ming Chen).
- Add preliminary support for the Platform Runtime Mechanism (PRM) to
allow the AML interpreter to call PRM functions (Erik Kaneda).
- Address some issues related to the handling of device dependencies
reported by _DEP in the ACPI device enumeration code and clean up
some related pieces of it (Rafael Wysocki).
- Improve the tracking of states of ACPI power resources (Rafael
Wysocki).
- Improve ACPI support for suspend-to-idle on AMD systems (Alex
Deucher, Mario Limonciello, Pratik Vishwakarma).
- Continue the unification and cleanup of message printing in the
ACPI code (Hanjun Guo, Heiner Kallweit).
- Fix possible buffer overrun issue with the description_show() sysfs
attribute method (Krzysztof Wilczyński).
- Improve the acpi_mask_gpe kernel command line parameter handling
and clean up the core ACPI code related to sysfs (Andy Shevchenko,
Baokun Li, Clayton Casciato).
- Postpone bringing devices in the general ACPI PM domain to D0
during resume from system-wide suspend until they are really needed
(Dmitry Torokhov).
- Make the ACPI processor driver fix up C-state latency if not
ordered (Mario Limonciello).
- Add support for identifying devices depening on the given one that
are not its direct descendants with the help of _DEP (Daniel
Scally).
- Extend the checks related to ACPI IRQ overrides on x86 in order to
avoid false-positives (Hui Wang).
- Add battery DPTF participant for Intel SoCs (Sumeet Pawnikar).
- Rearrange the ACPI fan driver and device power management code to
use a common list of device IDs (Rafael Wysocki).
- Fix clang CFI violation in the ACPI BGRT table parsing code and
clean it up (Nathan Chancellor).
- Add GPE-related quirks for some laptops to the EC driver (Chris
Chiu, Zhang Rui).
- Make the ACPI PPTT table parsing code populate the cache-id value
if present in the firmware (James Morse).
- Remove redundant clearing of context->ret.pointer from
acpi_run_osc() (Hans de Goede).
- Add missing acpi_put_table() in acpi_init_fpdt() (Jing Xiangfeng).
- Make ACPI APEI handle ARM Processor Error CPER records like Memory
Error ones to avoid user space task lockups (Xiaofei Tan).
- Stop warning about disabled ACPI in APEI (Jon Hunter).
- Fix fall-through warning for Clang in the SBSHC driver (Gustavo A.
R. Silva).
- Add custom DSDT file as Makefile prerequisite (Richard Fitzgerald).
- Initialize local variable to avoid garbage being returned (Colin
Ian King).
- Simplify assorted pieces of code, address assorted coding style and
documentation issues and comment typos (Baokun Li, Christophe
JAILLET, Clayton Casciato, Liu Shixin, Shaokun Zhang, Wei Yongjun,
Yang Li, Zhen Lei)"
* tag 'acpi-5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (97 commits)
ACPI: PM: postpone bringing devices to D0 unless we need them
ACPI: tables: Add custom DSDT file as makefile prerequisite
ACPI: bgrt: Use sysfs_emit
ACPI: bgrt: Fix CFI violation
ACPI: EC: trust DSDT GPE for certain HP laptop
ACPI: scan: Simplify acpi_table_events_fn()
ACPI: PM: Adjust behavior for field problems on AMD systems
ACPI: PM: s2idle: Add support for new Microsoft UUID
ACPI: PM: s2idle: Add support for multiple func mask
ACPI: PM: s2idle: Refactor common code
ACPI: PM: s2idle: Use correct revision id
ACPI: sysfs: Remove tailing return statement in void function
ACPI: sysfs: Use __ATTR_RO() and __ATTR_RW() macros
ACPI: sysfs: Sort headers alphabetically
ACPI: sysfs: Refactor param_get_trace_state() to drop dead code
ACPI: sysfs: Unify pattern of memory allocations
ACPI: sysfs: Allow bitmap list to be supplied to acpi_mask_gpe
ACPI: sysfs: Make sparse happy about address space in use
ACPI: scan: Fix race related to dropping dependencies
ACPI: scan: Reorganize acpi_device_add()
...
Pull power management updates from Rafael Wysocki:
"These add hybrid processors support to the intel_pstate driver and
make it work with more processor models when HWP is disabled, make the
intel_idle driver use special C6 idle state paremeters when package
C-states are disabled, add cooling support to the tegra30 devfreq
driver, rework the TEO (timer events oriented) cpuidle governor,
extend the OPP (operating performance points) framework to use the
required-opps DT property in more cases, fix some issues and clean up
a number of assorted pieces of code.
Specifics:
- Make intel_pstate support hybrid processors using abstract
performance units in the HWP interface (Rafael Wysocki).
- Add Icelake servers and Cometlake support in no-HWP mode to
intel_pstate (Giovanni Gherdovich).
- Make cpufreq_online() error path be consistent with the CPU device
removal path in cpufreq (Rafael Wysocki).
- Clean up 3 cpufreq drivers and the statistics code (Hailong Liu,
Randy Dunlap, Shaokun Zhang).
- Make intel_idle use special idle state parameters for C6 when
package C-states are disabled (Chen Yu).
- Rework the TEO (timer events oriented) cpuidle governor to address
some theoretical shortcomings in it (Rafael Wysocki).
- Drop unneeded semicolon from the TEO governor (Wan Jiabing).
- Modify the runtime PM framework to accept unassigned suspend and
resume callback pointers (Ulf Hansson).
- Improve pm_runtime_get_sync() documentation (Krzysztof Kozlowski).
- Improve device performance states support in the generic power
domains (genpd) framework (Ulf Hansson).
- Fix some documentation issues in genpd (Yang Yingliang).
- Make the operating performance points (OPP) framework use the
required-opps DT property in use cases that are not related to
genpd (Hsin-Yi Wang).
- Make lazy_link_required_opp_table() use list_del_init instead of
list_del/INIT_LIST_HEAD (Yang Yingliang).
- Simplify wake IRQs handling in the core system-wide sleep support
code and clean up some coding style inconsistencies in it (Tian
Tao, Zhen Lei).
- Add cooling support to the tegra30 devfreq driver and improve its
DT bindings (Dmitry Osipenko).
- Fix some assorted issues in the devfreq core and drivers (Chanwoo
Choi, Dong Aisheng, YueHaibing)"
* tag 'pm-5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (39 commits)
PM / devfreq: passive: Fix get_target_freq when not using required-opp
cpufreq: Make cpufreq_online() call driver->offline() on errors
opp: Allow required-opps to be used for non genpd use cases
cpuidle: teo: remove unneeded semicolon in teo_select()
dt-bindings: devfreq: tegra30-actmon: Add cooling-cells
dt-bindings: devfreq: tegra30-actmon: Convert to schema
PM / devfreq: userspace: Use DEVICE_ATTR_RW macro
PM: runtime: Clarify documentation when callbacks are unassigned
PM: runtime: Allow unassigned ->runtime_suspend|resume callbacks
PM: runtime: Improve path in rpm_idle() when no callback
PM: hibernate: remove leading spaces before tabs
PM: sleep: remove trailing spaces and tabs
PM: domains: Drop/restore performance state votes for devices at runtime PM
PM: domains: Return early if perf state is already set for the device
PM: domains: Split code in dev_pm_genpd_set_performance_state()
cpuidle: teo: Use kerneldoc documentation in admin-guide
cpuidle: teo: Rework most recent idle duration values treatment
cpuidle: teo: Change the main idle state selection logic
cpuidle: teo: Cosmetic modification of teo_select()
cpuidle: teo: Cosmetic modifications of teo_update()
...
Pull timer updates from Thomas Gleixner:
"Time and clocksource/clockevent related updates:
Core changes:
- Infrastructure to support per CPU "broadcast" devices for per CPU
clockevent devices which stop in deep idle states. This allows us
to utilize the more efficient architected timer on certain ARM SoCs
for normal operation instead of permanentely using the slow to
access SoC specific clockevent device.
- Print the name of the broadcast/wakeup device in /proc/timer_list
- Make the clocksource watchdog more robust against delays between
reading the current active clocksource and the watchdog
clocksource. Such delays can be caused by NMIs, SMIs and vCPU
preemption.
Handle this by reading the watchdog clocksource twice, i.e. before
and after reading the current active clocksource. In case that the
two watchdog reads shows an excessive time delta, the read sequence
is repeated up to 3 times.
- Improve the debug output and add a test module for the watchdog
mechanism.
- Reimplementation of the venerable time64_to_tm() function with a
faster and significantly smaller version. Straight from the source,
i.e. the author of the related research paper contributed this!
Driver changes:
- No new drivers, not even new device tree bindings!
- Fixes, improvements and cleanups and all over the place"
* tag 'timers-core-2021-06-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (30 commits)
time/kunit: Add missing MODULE_LICENSE()
time: Improve performance of time64_to_tm()
clockevents: Use list_move() instead of list_del()/list_add()
clocksource: Print deviation in nanoseconds when a clocksource becomes unstable
clocksource: Provide kernel module to test clocksource watchdog
clocksource: Reduce clocksource-skew threshold
clocksource: Limit number of CPUs checked for clock synchronization
clocksource: Check per-CPU clock synchronization when marked unstable
clocksource: Retry clock read if long delays detected
clockevents: Add missing parameter documentation
clocksource/drivers/timer-ti-dm: Drop unnecessary restore
clocksource/arm_arch_timer: Improve Allwinner A64 timer workaround
clocksource/drivers/arm_global_timer: Remove duplicated argument in arm_global_timer
clocksource/drivers/arm_global_timer: Make symbol 'gt_clk_rate_change_nb' static
arm: zynq: don't disable CONFIG_ARM_GLOBAL_TIMER due to CONFIG_CPU_FREQ anymore
clocksource/drivers/arm_global_timer: Implement rate compensation whenever source clock changes
clocksource/drivers/ingenic: Rename unreasonable array names
clocksource/drivers/timer-ti-dm: Save and restore timer TIOCP_CFG
clocksource/drivers/mediatek: Ack and disable interrupts on suspend
clocksource/drivers/samsung_pwm: Constify source IO memory
...
This introduces a new sysctl vm.percpu_pagelist_high_fraction. It is
similar to the old vm.percpu_pagelist_fraction. The old sysctl increased
both pcp->batch and pcp->high with the higher pcp->high potentially
reducing zone->lock contention. However, the higher pcp->batch value also
potentially increased allocation latency while the PCP was refilled. This
sysctl only adjusts pcp->high so that zone->lock contention is potentially
reduced but allocation latency during a PCP refill remains the same.
# grep -E "high:|batch" /proc/zoneinfo | tail -2
high: 649
batch: 63
# sysctl vm.percpu_pagelist_high_fraction=8
# grep -E "high:|batch" /proc/zoneinfo | tail -2
high: 35071
batch: 63
# sysctl vm.percpu_pagelist_high_fraction=64
high: 4383
batch: 63
# sysctl vm.percpu_pagelist_high_fraction=0
high: 649
batch: 63
[mgorman@techsingularity.net: fix documentation]
Link: https://lkml.kernel.org/r/20210528151010.GQ30378@techsingularity.net
Link: https://lkml.kernel.org/r/20210525080119.5455-7-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Calculate pcp->high based on zone sizes and active CPUs", v2.
The per-cpu page allocator (PCP) is meant to reduce contention on the zone
lock but the sizing of batch and high is archaic and neither takes the
zone size into account or the number of CPUs local to a zone. With larger
zones and more CPUs per node, the contention is getting worse.
Furthermore, the fact that vm.percpu_pagelist_fraction adjusts both batch
and high values means that the sysctl can reduce zone lock contention but
also increase allocation latencies.
This series disassociates pcp->high from pcp->batch and then scales
pcp->high based on the size of the local zone with limited impact to
reclaim and accounting for active CPUs but leaves pcp->batch static. It
also adapts the number of pages that can be on the pcp list based on
recent freeing patterns.
The motivation is partially to adjust to larger memory sizes but is also
driven by the fact that large batches of page freeing via release_pages()
often shows zone contention as a major part of the problem. Another is a
bug report based on an older kernel where a multi-terabyte process can
takes several minutes to exit. A workaround was to use
vm.percpu_pagelist_fraction to increase the pcp->high value but testing
indicated that a production workload could not use the same values because
of an increase in allocation latencies. Unfortunately, I cannot reproduce
this test case myself as the multi-terabyte machines are in active use but
it should alleviate the problem.
The series aims to address both and partially acts as a pre-requisite.
pcp only works with order-0 which is useless for SLUB (when using high
orders) and THP (unconditionally). To store high-order pages on PCP, the
pcp->high values need to be increased first.
This patch (of 6):
The vm.percpu_pagelist_fraction is used to increase the batch and high
limits for the per-cpu page allocator (PCP). The intent behind the sysctl
is to reduce zone lock acquisition when allocating/freeing pages but it
has a problem. While it can decrease contention, it can also increase
latency on the allocation side due to unreasonably large batch sizes.
This leads to games where an administrator adjusts
percpu_pagelist_fraction on the fly to work around contention and
allocation latency problems.
This series aims to alleviate the problems with zone lock contention while
avoiding the allocation-side latency problems. For the purposes of
review, it's easier to remove this sysctl now and reintroduce a similar
sysctl later in the series that deals only with pcp->high.
Link: https://lkml.kernel.org/r/20210525080119.5455-1-mgorman@techsingularity.net
Link: https://lkml.kernel.org/r/20210525080119.5455-2-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pm-cpufreq:
cpufreq: Make cpufreq_online() call driver->offline() on errors
cpufreq: loongson2: Remove unused linux/sched.h headers
cpufreq: sh: Remove unused linux/sched.h headers
cpufreq: stats: Clean up local variable in cpufreq_stats_create_table()
cpufreq: intel_pstate: hybrid: Fix build with CONFIG_ACPI unset
cpufreq: sc520_freq: add 'fallthrough' to one case
cpufreq: intel_pstate: Add Cometlake support in no-HWP mode
cpufreq: intel_pstate: Add Icelake servers support in no-HWP mode
cpufreq: intel_pstate: hybrid: CPU-specific scaling factor
cpufreq: intel_pstate: hybrid: Avoid exposing two global attributes
* pm-cpuidle:
cpuidle: teo: remove unneeded semicolon in teo_select()
cpuidle: teo: Use kerneldoc documentation in admin-guide
cpuidle: teo: Rework most recent idle duration values treatment
cpuidle: teo: Change the main idle state selection logic
cpuidle: teo: Cosmetic modification of teo_select()
cpuidle: teo: Cosmetic modifications of teo_update()
intel_idle: Adjust the SKX C6 parameters if PC6 is disabled
Pull pstore updates from Kees Cook:
"Use normal block device I/O path for pstore/blk. (Christoph Hellwig,
Kees Cook, Pu Lehui)"
* tag 'pstore-v5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
pstore/blk: Include zone in pstore_device_info
pstore/blk: Fix kerndoc and redundancy on blkdev param
pstore/blk: Use the normal block device I/O path
pstore/blk: Move verify_size() macro out of function
pstore/blk: Improve failure reporting
Pull documentation updates from Jonathan Corbet:
"This was a reasonably active cycle for documentation; this includes:
- Some kernel-doc cleanups. That script is still regex onslaught from
hell, but it has gotten a little better.
- Improvements to the checkpatch docs, which are also used by the
tool itself.
- A major update to the pathname lookup documentation.
- Elimination of :doc: markup, since our automarkup magic can create
references from filenames without all the extra noise.
- The flurry of Chinese translation activity continues.
Plus, of course, the usual collection of updates, typo fixes, and
warning fixes"
* tag 'docs-5.14' of git://git.lwn.net/linux: (115 commits)
docs: path-lookup: use bare function() rather than literals
docs: path-lookup: update symlink description
docs: path-lookup: update get_link() ->follow_link description
docs: path-lookup: update WALK_GET, WALK_PUT desc
docs: path-lookup: no get_link()
docs: path-lookup: update i_op->put_link and cookie description
docs: path-lookup: i_op->follow_link replaced with i_op->get_link
docs: path-lookup: Add macro name to symlink limit description
docs: path-lookup: remove filename_mountpoint
docs: path-lookup: update do_last() part
docs: path-lookup: update path_mountpoint() part
docs: path-lookup: update path_to_nameidata() part
docs: path-lookup: update follow_managed() part
docs: Makefile: Use CONFIG_SHELL not SHELL
docs: Take a little noise out of the build process
docs: x86: avoid using ReST :doc:`foo` markup
docs: virt: kvm: s390-pv-boot.rst: avoid using ReST :doc:`foo` markup
docs: userspace-api: landlock.rst: avoid using ReST :doc:`foo` markup
docs: trace: ftrace.rst: avoid using ReST :doc:`foo` markup
docs: trace: coresight: coresight.rst: avoid using ReST :doc:`foo` markup
...
Pull media updates from Mauro Carvalho Chehab:
- V4L2 core control API was split into separate files
- New RC maps: tango and tc-90405
- Hantro driver got support for G2/HEVC decoder
- av7710 is moving to staging, together with some legacy APIs
- several cleanups related to compat_ioctl32 code
- Move the MPEG-2 stateless control type out of staging
- Address several issues with RPM get logic on media drivers
- Lots of cleanups, bug fixes and improvements.
* tag 'media/v5.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (394 commits)
media: s5p-mfc: Fix display delay control creation
media: mtk-vpu: on suspend, read/write regs only if vpu is running
media: video-mux: Skip dangling endpoints
media: Fix Media Controller API config checks
media: i2c: rdacm20: Re-work ov10635 reset
media: i2c: rdacm20: Check return values
media: i2c: rdacm20: Report camera module name
media: i2c: rdacm20: Enable noise immunity
media: i2c: rdacm20: Embed 'serializer' field
media: i2c: rdacm21: Power up OV10640 before OV490
media: i2c: rdacm21: Fix OV10640 powerup
media: i2c: rdacm21: Add delay after OV490 reset
media: i2c: max9271: Introduce wake_up() function
media: i2c: max9271: Check max9271_write() return
media: i2c: max9286: Rework comments in .bound()
media: i2c: max9286: Define high channel amplitude
media: i2c: max9286: Cache channel amplitude
media: i2c: max9286: Rename reverse_channel_mv
media: i2c: max9286: Adjust parameters indent
media: hantro: add support for Rockchip RK3036
...
Commit 95b88f4d71 ("dm writecache: pause
writeback if cache full and origin being written directly") introduced a
code that pauses cache flushing if we are issuing writes directly to the
origin.
Improve that initial commit by making the timeout code configurable
(via the option "pause_writeback"). Also change the default from 1s to
3s because it performed better.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Pull x86 splitlock updates from Ingo Molnar:
- Add the "ratelimit:N" parameter to the split_lock_detect= boot
option, to rate-limit the generation of bus-lock exceptions.
This is both easier on system resources and kinder to offending
applications than the current policy of outright killing them.
- Document the split-lock detection feature and its parameters.
* tag 'x86-splitlock-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
Documentation/x86: Add ratelimit in buslock.rst
Documentation/admin-guide: Add bus lock ratelimit
x86/bus_lock: Set rate limit for bus lock
Documentation/x86: Add buslock.rst
Pull x86 cleanups from Ingo Molnar:
"Misc cleanups & removal of obsolete code"
* tag 'x86-cleanups-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/sgx: Correct kernel-doc's arg name in sgx_encl_release()
doc: Remove references to IBM Calgary
x86/setup: Document that Windows reserves the first MiB
x86/crash: Remove crash_reserve_low_1M()
x86/setup: Remove CONFIG_X86_RESERVE_LOW and reservelow= options
x86/alternative: Align insn bytes vertically
x86: Fix leftover comment typos
x86/asm: Simplify __smp_mb() definition
x86/alternatives: Make the x86nops[] symbol static
Add a "metadata_only" parameter that when present: only metadata is
promoted to the cache. This option improves performance for heavier
REQ_META workloads (e.g. device-mapper-test-suite's "git clone and
checkout" benchmark improves from 341s to 312s).
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
When the clocksource watchdog marks a clock as unstable, this might
be due to that clock being unstable or it might be due to delays that
happen to occur between the reads of the two clocks. It would be good
to have a way of testing the clocksource watchdog's ability to
distinguish between these two causes of clock skew and instability.
Therefore, provide a new clocksource-wdtest module selected by a new
TEST_CLOCKSOURCE_WATCHDOG Kconfig option. This module has a single module
parameter named "holdoff" that provides the number of seconds of delay
before testing should start, which defaults to zero when built as a module
and to 10 seconds when built directly into the kernel. Very large systems
that boot slowly may need to increase the value of this module parameter.
This module uses hand-crafted clocksource structures to do its testing,
thus avoiding messing up timing for the rest of the kernel and for user
applications. This module first verifies that the ->uncertainty_margin
field of the clocksource structures are set sanely. It then tests the
delay-detection capability of the clocksource watchdog, increasing the
number of consecutive delays injected, first provoking console messages
complaining about the delays and finally forcing a clock-skew event.
Unexpected test results cause at least one WARN_ON_ONCE() console splat.
If there are no splats, the test has passed. Finally, it fuzzes the
value returned from a clocksource to test the clocksource watchdog's
ability to detect time skew.
This module checks the state of its clocksource after each test, and
uses WARN_ON_ONCE() to emit a console splat if there are any failures.
This should enable all types of test frameworks to detect any such
failures.
This facility is intended for diagnostic use only, and should be avoided
on production systems.
Reported-by: Chris Mason <clm@fb.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Feng Tang <feng.tang@intel.com>
Link: https://lore.kernel.org/r/20210527190124.440372-5-paulmck@kernel.org
Currently, if skew is detected on a clock marked CLOCK_SOURCE_VERIFY_PERCPU,
that clock is checked on all CPUs. This is thorough, but might not be
what you want on a system with a few tens of CPUs, let alone a few hundred
of them.
Therefore, by default check only up to eight randomly chosen CPUs. Also
provide a new clocksource.verify_n_cpus kernel boot parameter. A value of
-1 says to check all of the CPUs, and a non-negative value says to randomly
select that number of CPUs, without concern about selecting the same CPU
multiple times. However, make use of a cpumask so that a given CPU will be
checked at most once.
Suggested-by: Thomas Gleixner <tglx@linutronix.de> # For verify_n_cpus=1.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Feng Tang <feng.tang@intel.com>
Link: https://lore.kernel.org/r/20210527190124.440372-3-paulmck@kernel.org
When the clocksource watchdog marks a clock as unstable, this might be due
to that clock being unstable or it might be due to delays that happen to
occur between the reads of the two clocks. Yes, interrupts are disabled
across those two reads, but there are no shortage of things that can delay
interrupts-disabled regions of code ranging from SMI handlers to vCPU
preemption. It would be good to have some indication as to why the clock
was marked unstable.
Therefore, re-read the watchdog clock on either side of the read from the
clock under test. If the watchdog clock shows an excessive time delta
between its pair of reads, the reads are retried.
The maximum number of retries is specified by a new kernel boot parameter
clocksource.max_cswd_read_retries, which defaults to three, that is, up to
four reads, one initial and up to three retries. If more than one retry
was required, a message is printed on the console (the occasional single
retry is expected behavior, especially in guest OSes). If the maximum
number of retries is exceeded, the clock under test will be marked
unstable. However, the probability of this happening due to various sorts
of delays is quite small. In addition, the reason (clock-read delays) for
the unstable marking will be apparent.
Reported-by: Chris Mason <clm@fb.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Feng Tang <feng.tang@intel.com>
Link: https://lore.kernel.org/r/20210527190124.440372-1-paulmck@kernel.org
Introduce an rq-qos policy that assigns an I/O priority to requests based
on blk-cgroup configuration settings. This policy has the following
advantages over the ioprio_set() system call:
- This policy is cgroup based so it has all the advantages of cgroups.
- While ioprio_set() does not affect page cache writeback I/O, this rq-qos
controller affects page cache writeback I/O for filesystems that support
assiociating a cgroup with writeback I/O. See also
Documentation/admin-guide/cgroup-v2.rst.
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Cc: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20210618004456.7280-5-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The conversion tools used during DocBook/LaTeX/html/Markdown->ReST
conversion and some cut-and-pasted text contain some characters that
aren't easily reachable on standard keyboards and/or could cause
troubles when parsed by the documentation build system.
Replace the occurences of the following characters:
- U+00a0 (' '): NO-BREAK SPACE
as it can cause lines being truncated on PDF output
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/551a2af0e654226067e5c376d3e2d959cc738f39.1623826294.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Currently we need to use as many acpi_mask_gpe options as we want to have
GPEs to be masked. Even with two it already becomes inconveniently large
the kernel command line.
Instead, allow acpi_mask_gpe to represent bitmap list.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Add a kernel command line option that disables printing of events to
console at late_initcall_sync(). This is useful when needing to see
specific events written to console on boot up, but not wanting it when
user space starts, as user space may make the console so noisy that the
system becomes inoperable.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Commit bf382fb0bcef4 ("block: remove legacy IO schedulers", Oct 12 2018)
removes the CFQ scheduler, together with blkio.weight and
blkio.weight_device described in cgroup v1 documentation. Users are
supposed to use the BFQ scheduler, which cgroup file for setting weight
is blkio.bfq.weight, but there is no way to set per-device weight.
Later, commit 795fe54c2a per-device weights for BFQ, meaning that
blkio.bfq.weight and blkio.bfq.weight_device can be used in a way
similar to the old CFQ cgroup interface.
Yet, the cgroup v1 docs were never updated. Fix this:
- use the new file names;
- fix the range for weight (used to be 10..1000, now 1..1000);
- link to BFQ scheduler docs.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Remove redundant details of blkdev and fix up resulting kerndoc.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
Stop poking into block layer internals and just open the block device
file an use kernel_read and kernel_write on it. Note that this means
the transformation from name_to_dev_t can't be used anymore when
pstore_blk is loaded as a module: a full filesystem device path name
must be used instead. Additionally removes ":internal:" kerndoc link,
since no such documentation remains.
Co-developed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
The :doc:`foo` tag is auto-generated via automarkup.py.
So, use the filename at the sources, instead of :doc:`foo`.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
The :doc:`foo` tag is auto-generated via automarkup.py.
So, use the filename at the sources, instead of :doc:`foo`.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Some parts of the guide are aged, hence need be updated.
1) The backup area of the 1st 640K on X86_64 has been removed
by below commits, update the description accordingly.
commit 7c321eb2b8 ("x86/kdump: Remove the backup region handling")
commit 6f599d8423 ("x86/kdump: Always reserve the low 1M when the crashkernel option is specified")
2) Sort out the descripiton of "crashkernel syntax" part.
3) And some other minor cleanups.
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
Link: https://lore.kernel.org/r/20210609083218.GB591017@MiWiFi-R3L-srv
[jc: added blank line to fix added build warning]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
There are two descriptions of the TEO (Timer Events Oriented) cpuidle
governor in the kernel source tree, one in the C file containing its
code and one in cpuidle.rst which is part of admin-guide.
Instead of trying to keep them both in sync and in order to reduce
text duplication, include the governor description from the C file
directly into cpuidle.rst.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
PSI accounts stalls for each cgroup separately and aggregates it at each
level of the hierarchy. This causes additional overhead with psi_avgs_work
being called for each cgroup in the hierarchy. psi_avgs_work has been
highly optimized, however on systems with large number of cgroups the
overhead becomes noticeable.
Systems which use PSI only at the system level could avoid this overhead
if PSI can be configured to skip per-cgroup stall accounting.
Add "cgroup_disable=pressure" kernel command-line option to allow
requesting system-wide only pressure stall accounting. When set, it
keeps system-wide accounting under /proc/pressure/ but skips accounting
for individual cgroups and does not expose PSI nodes in cgroup hierarchy.
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
The CONFIG_X86_RESERVE_LOW build time and reservelow= command line option
allowed to control the amount of memory under 1M that would be reserved at
boot to avoid using memory that can be potentially clobbered by BIOS.
Since the entire range under 1M is always reserved there is no need for
these options anymore and they can be removed.
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210601075354.5149-3-rppt@kernel.org
