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Remove <linux/hex.h> from <linux/kernel.h> and update all users/callers of
hex.h interfaces to directly #include <linux/hex.h> as part of the process
of putting kernel.h on a diet.
Removing hex.h from kernel.h means that 36K C source files don't have to
pay the price of parsing hex.h for the roughly 120 C source files that
need it.
This change has been build-tested with allmodconfig on most ARCHes. Also,
all users/callers of <linux/hex.h> in the entire source tree have been
updated if needed (if not already #included).
Link: https://lkml.kernel.org/r/20251215005206.2362276-1-rdunlap@infradead.org
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Yury Norov (NVIDIA) <yury.norov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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__tlb_remove_page_size() is only used in tlb_remove_page_size() with
@delay_remap set to false and it is passed directly to
__tlb_remove_folio_pages_size().
Remove @delay_remap of __tlb_remove_page_size() and call
__tlb_remove_folio_pages_size() with false @delay_remap.
Link: https://lkml.kernel.org/r/20251231030026.15938-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: SeongJae Park <sj@kernel.org>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com> # s390
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Several helper functions for managing node and zone states have become
obsolete and no longer have any callers within the kernel.
inc_node_state()
inc_zone_state()
dec_zone_state()
This commit removes the dead code.
Link: https://lkml.kernel.org/r/20251225210213.2553-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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This reintroduces a concept removed by: commit d6cb41cc44c6 ("mm, hugetlb:
remove hugepages_treat_as_movable sysctl")
This sysctl provides flexibility between ZONE_MOVABLE use cases:
1) onlining memory in ZONE_MOVABLE to maintain hotplug compatibility
2) onlining memory in ZONE_MOVABLE to make hugepage allocate reliable
When ZONE_MOVABLE is used to make huge page allocation more reliable,
disallowing gigantic pages memory in this region is pointless. If hotplug
is not a requirement, we can loosen the restrictions to allow 1GB gigantic
pages in ZONE_MOVABLE.
Since 1GB can be difficult to migrate / has impacts on compaction /
defragmentation, we don't enable this by default. Notably, 1GB pages can
only be migrated if another 1GB page is available - so hot-unplug will
fail if such a page cannot be found.
However, since there are scenarios where gigantic pages are migratable, we
should allow use of these on movable regions.
When not valid 1GB is available for migration, hot-unplug will retry
indefinitely (or until interrupted). For example:
echo 0 > node0/hugepages/..-1GB/nr_hugepages # clear node0 1GB pages
echo 1 > node1/hugepages/..-1GB/nr_hugepages # reserve node1 1GB page
./alloc_huge_node1 & # Allocate a 1GB page on node1
./node1_offline & # attempt to offline all node1 memory
echo 1 > node0/hugepages/..-1GB/nr_hugepages # reserve node0 1GB page
In this example, node1_offline will block indefinitely until the final
step, when a node0 1GB page is made available.
Note: Boot-time CMA is not possible for driver-managed hotplug memory, as
CMA requires the memory to be registered as SystemRAM at boot time.
Additionally, 1GB huge pages are not supported by THP.
Link: https://lkml.kernel.org/r/20251221125603.2364174-1-gourry@gourry.net
Signed-off-by: Gregory Price <gourry@gourry.net>
Suggested-by: David Rientjes <rientjes@google.com>
Link: https://lore.kernel.org/all/20180201193132.Hk7vI_xaU%25akpm@linux-foundation.org/
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "David Hildenbrand (Red Hat)" <david@kernel.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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commit d24062914837 ("fork: use __mt_dup() to duplicate maple tree in
dup_mmap()"), removed the only user and mas_expected_entries has been
removed, since commit e3852a1213ffc ("maple_tree: Drop bulk insert
support"). Also cleanup the mas_expected_entries in maple_tree.h.
No functional change.
Link: https://lkml.kernel.org/r/20251106110929.3522073-1-guanwentao@uniontech.com
Signed-off-by: Wentao Guan <guanwentao@uniontech.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Cheng Nie <niecheng1@uniontech.com>
Cc: Guan Wentao <guanwentao@uniontech.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Jann Horn <jannh@google.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The current description of contexts where it's invalid to make GFP_ATOMIC
and GFP_NOWAIT calls is rather vague.
Replace this with a direct description of the actual contexts of concern
and refer to the RT docs where this is explained more discursively.
While rejigging this prose, also move the documentation of GFP_NOWAIT to
the GFP_NOWAIT section.
Link: https://lore.kernel.org/all/d912480a-5229-4efe-9336-b31acded30f5@suse.cz/
Link: https://lkml.kernel.org/r/20251219-b4-gfp_atomic-comment-v2-1-4c4ce274c2b6@google.com
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Use bool for 'hashdist' and replace simple_strtoul() with kstrtobool() for
parsing the 'hashdist=' boot parameter. Unlike simple_strtoul(), which
returns an unsigned long, kstrtobool() converts the string directly to
bool and avoids implicit casting.
Check the return value of kstrtobool() and reject invalid values. This
adds error handling while preserving behavior for existing values, and
removes use of the deprecated simple_strtoul() helper. The current code
silently sets 'hashdist = 0' if parsing fails, instead of leaving the
default value (HASHDIST_DEFAULT) unchanged.
Additionally, kstrtobool() accepts common boolean strings such as "on" and
"off".
Link: https://lkml.kernel.org/r/20251217110214.50807-1-thorsten.blum@linux.dev
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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struct maple_alloc is deprecated after the maple tree conversion to
sheaves, remove the references from the header file.
Link: https://lkml.kernel.org/r/20251203224511.469978-1-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Laptop mode was introduced to save battery, by delaying and consolidating
writes and thereby maximize the time rotating hard drives wouldn't have to
spin.
Luckily, rotating hard drives, with their high spin-up times and power
draw, are a thing of the past for battery-powered devices. Reclaim has
also since changed to not write single filesystem pages anymore, and
regular filesystem writeback is lumpy by design.
The juice doesn't appear worth the squeeze anymore. The footprint of the
feature is small, but nevertheless it's a complicating factor in mm,
block, filesystems. Developers don't think about it, and it likely hasn't
been tested with new reclaim and writeback changes in years.
Let's sunset it. Keep the sysctl with a deprecation warning around for a
few more cycles, but remove all functionality behind it.
[akpm@linux-foundation.org: fix Documentation/admin-guide/laptops/index.rst]
Link: https://lkml.kernel.org/r/20251216185201.GH905277@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Deepanshu Kartikey <kartikey406@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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DAMON users can read DAMOS stats via DAMON sysfs interface. It enables
efficient, simple and flexible usages of the stats. Especially for
systems not having advanced tools like perf or bpftrace, that can be
useful. But if the advanced tools are available, exposing the stats via
tracepoint can reduce unnecessary reimplementation of the wheels. Add a
new tracepoint for DAMOS stats, namely damos_stat_after_apply_interval.
The tracepoint is triggered for each scheme's apply interval and exposes
the whole stat values. If the user needs sub-apply interval information
for any chance, damos_before_apply tracepoint could be used.
Link: https://lkml.kernel.org/r/20251216080128.42991-13-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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There are DAMOS use cases that require user-space centric control of its
activation and deactivation. Having the control plane on the user-space,
or using DAMOS as a way for monitoring results collection are such
examples.
DAMON parameters online commit, DAMOS quotas and watermarks can be useful
for this purpose. However, those features work only at the
sub-DAMON-snapshot level. In some use cases, the DAMON-snapshot level
control is required. For example, in DAMOS-based monitoring results
collection use case, the user online-installs a DAMOS scheme with
DAMOS_STAT action, wait it be applied to whole regions of a single
DAMON-snapshot, retrieves the stats and tried regions information, and
online-uninstall the scheme. It is efficient to ensure the lifetime of
the scheme as no more no less one snapshot consumption.
To support such use cases, introduce a new DAMOS core API per-scheme
parameter, namely max_nr_snapshots. As the name implies, it is the upper
limit of nr_snapshots, which is a DAMOS stat that represents the number of
DAMON-snapshots that the scheme has fully applied. If the limit is set
with a non-zero value and nr_snapshots reaches or exceeds the limit, the
scheme is deactivated.
Link: https://lkml.kernel.org/r/20251216080128.42991-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Commit 0e92c2ee9f45 ("mm/damon/schemes: account scheme actions that
successfully applied") has replaced ->stat_count and ->stat_sz of 'struct
damos' with ->stat. The commit mistakenly did not update the related
kernel doc comment, though. Update the comment.
Link: https://lkml.kernel.org/r/20251216080128.42991-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "mm/damon: introduce {,max_}nr_snapshots and tracepoint for
damos stats".
Introduce three changes for improving DAMOS stat's provided information,
deterministic control, and reading usability.
DAMOS provides stats that are important for understanding its behavior.
It lacks information about how many DAMON-generated monitoring output
snapshots it has worked on. Add a new stat, nr_snapshots, to show the
information.
Users can control DAMOS schemes in multiple ways. Using the online
parameters commit feature, they can install and uninstall DAMOS schemes
whenever they want while keeping DAMON runs. DAMOS quotas and watermarks
can be used for manually or automatically turning on/off or adjusting the
aggressiveness of the scheme. DAMOS filters can be used for applying the
scheme to specific memory entities based on their types and locations.
Some users want their DAMOS scheme to be applied to only specific number
of DAMON snapshots, for more deterministic control. One example use case
is tracepoint based snapshot reading. Add a new knob, max_nr_snapshots,
to support this. If the nr_snapshots parameter becomes same to or greater
than the value of this parameter, the scheme is deactivated.
Users can read DAMOS stats via DAMON's sysfs interface. For deep level
investigations on environments having advanced tools like perf and
bpftrace, exposing the stats via a tracepoint can be useful. Implement a
new tracepoint, namely damon:damos_stat_after_apply_interval.
First five patches (patches 1-5) of this series implement the new stat,
nr_snapshots, on the core layer (patch 1), expose on DAMON sysfs user
interface (patch 2), and update documents (patches 3-5).
Following six patches (patches 6-11) are for the new stat based DAMOS
deactivation (max_nr_snapshots). The first one (patch 6) of this group
updates a kernel-doc comment before making further changes. Then an
implementation of it on the core layer (patch 7), an introduction of a new
DAMON sysfs interface file for users of the feature (patch 8), and three
updates of the documents (patches 9-11) follow.
The final one (patch 12) introduces the new tracepoint that exposes the
DAMOS stat values for each scheme apply interval.
This patch (of 12):
DAMON generates monitoring results snapshots for every sampling interval.
DAMOS applies given schemes on the regions of the snapshots, for every
apply interval of the scheme.
DAMOS stat informs a given scheme has tried to how many memory entities
and applied, in the region and byte level. In some use cases including
user-space oriented tuning and investigations, it is useful to know that
in the DAMON-snapshot level. Introduce a new stat, namely nr_snapshots
for DAMON core API callers.
[sj@kernel.org: fix wrong list_is_last() call in damons_is_last_region()]
Link: https://lkml.kernel.org/r/20260114152049.99727-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20251216080128.42991-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20251216080128.42991-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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In addition to slab objects, this function is used for resolving non-slab
kernel pointers. This has caused confusion in recent refactoring work.
Rename it to mem_cgroup_from_virt(), sticking with terminology established
by the virt_to_<foo>() converters.
Link: https://lore.kernel.org/linux-mm/20251113161424.GB3465062@cmpxchg.org/
Link: https://lkml.kernel.org/r/20251210154301.720133-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The mem_cgroup_size helper is used only in apply_proportional_protection
to read the current memory usage. Its semantics are unclear and
inconsistent with other sites, which directly call page_counter_read for
the same purpose.
Remove this helper and get its usage via mem_cgroup_protection for
clarity. Additionally, rename the local variable 'cgroup_size' to 'usage'
to better reflect its meaning.
No functional changes intended.
Link: https://lkml.kernel.org/r/20251211013019.2080004-3-chenridong@huaweicloud.com
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Lu Jialin <lujialin4@huawei.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Use batch clearing in clear_contig_highpages() instead of clearing a
single page at a time. Exposing larger ranges enables the processor to
optimize based on extent.
To do this we just switch to using clear_user_highpages() which would in
turn use clear_user_pages() or clear_pages().
Batched clearing, when running under non-preemptible models, however, has
latency considerations. In particular, we need periodic invocations of
cond_resched() to keep to reasonable preemption latencies. This is a
problem because the clearing primitives do not, or might not be able to,
call cond_resched() to check if preemption is needed.
So, limit the worst case preemption latency by doing the clearing in units
of no more than PROCESS_PAGES_NON_PREEMPT_BATCH pages. (Preemptible
models already define away most of cond_resched(), so the batch size is
ignored when running under those.)
PROCESS_PAGES_NON_PREEMPT_BATCH: for architectures with "fast" clear-pages
(ones that define clear_pages()), we define it as 32MB worth of pages.
This is meant to be large enough to allow the processor to optimize the
operation and yet small enough that we see reasonable preemption latency
for when this optimization is not possible (ex. slow microarchitectures,
memory bandwidth saturation.)
This specific value also allows for a cacheline allocation elision
optimization (which might help unrelated applications by not evicting
potentially useful cache lines) that kicks in recent generations of AMD
Zen processors at around LLC-size (32MB is a typical size).
At the same time 32MB is small enough that even with poor clearing
bandwidth (say ~10GBps), time to clear 32MB should be well below the
scheduler's default warning threshold
(sysctl_resched_latency_warn_ms=100).
"Slow" architectures (don't have clear_pages()) will continue to use the
base value (single page).
Performance
==
Testing a demand fault workload shows a decent improvement in bandwidth
with pg-sz=1GB. Bandwidth with pg-sz=2MB stays flat.
$ perf bench mem mmap -p $pg-sz -f demand -s 64GB -l 5
contiguous-pages batched-pages
(GBps +- %stdev) (GBps +- %stdev)
pg-sz=2MB 23.58 +- 1.95% 25.34 +- 1.18% + 7.50% preempt=*
pg-sz=1GB 25.09 +- 0.79% 39.22 +- 2.32% + 56.31% preempt=none|voluntary
pg-sz=1GB 25.71 +- 0.03% 52.73 +- 0.20% [#] +110.16% preempt=full|lazy
[#] We perform much better with preempt=full|lazy because, not
needing explicit invocations of cond_resched() we can clear the
full extent (pg-sz=1GB) as a single unit which the processor
can optimize for.
(Unless otherwise noted, all numbers are on AMD Genoa (EPYC 9J13);
region-size=64GB, local node; 2.56 GHz, boost=0.)
Analysis
==
pg-sz=1GB: the improvement we see falls in two buckets depending on the
batch size in use.
For batch-size=32MB the number of cachelines allocated (L1-dcache-loads)
-- which stay relatively flat for smaller batches, start to drop off
because cacheline allocation elision kicks in. And as can be seen below,
at batch-size=1GB, we stop allocating cachelines almost entirely. (Not
visible here but from testing with intermediate sizes, the allocation
change kicks in only at batch-size=32MB and ramps up from there.)
contigous-pages 6,949,417,798 L1-dcache-loads # 883.599 M/sec ( +- 0.01% ) (35.75%)
3,226,709,573 L1-dcache-load-misses # 46.43% of all L1-dcache accesses ( +- 0.05% ) (35.75%)
batched,32MB 2,290,365,772 L1-dcache-loads # 471.171 M/sec ( +- 0.36% ) (35.72%)
1,144,426,272 L1-dcache-load-misses # 49.97% of all L1-dcache accesses ( +- 0.58% ) (35.70%)
batched,1GB 63,914,157 L1-dcache-loads # 17.464 M/sec ( +- 8.08% ) (35.73%)
22,074,367 L1-dcache-load-misses # 34.54% of all L1-dcache accesses ( +- 16.70% ) (35.70%)
The dropoff is also visible in L2 prefetch hits (miss numbers are
on similar lines):
contiguous-pages 3,464,861,312 l2_pf_hit_l2.all # 437.722 M/sec ( +- 0.74% ) (15.69%)
batched,32MB 883,750,087 l2_pf_hit_l2.all # 181.223 M/sec ( +- 1.18% ) (15.71%)
batched,1GB 8,967,943 l2_pf_hit_l2.all # 2.450 M/sec ( +- 17.92% ) (15.77%)
This largely decouples the frontend from the backend since the clearing
operation does not need to wait on loads from memory (we still need
cacheline ownership but that's a shorter path). This is most visible if
we rerun the test above with (boost=1, 3.66 GHz).
$ perf bench mem mmap -p $pg-sz -f demand -s 64GB -l 5
contiguous-pages batched-pages
(GBps +- %stdev) (GBps +- %stdev)
pg-sz=2MB 26.08 +- 1.72% 26.13 +- 0.92% - preempt=*
pg-sz=1GB 26.99 +- 0.62% 48.85 +- 2.19% + 80.99% preempt=none|voluntary
pg-sz=1GB 27.69 +- 0.18% 75.18 +- 0.25% +171.50% preempt=full|lazy
Comparing the batched-pages numbers from the boost=0 ones and these: for a
clock-speed gain of 42% we gain 24.5% for batch-size=32MB and 42.5% for
batch-size=1GB. In comparison the baseline contiguous-pages case and both
the pg-sz=2MB ones are largely backend bound so gain no more than ~10%.
Other platforms tested, Intel Icelakex (Oracle X9) and ARM64 Neoverse-N1
(Ampere Altra) both show an improvement of ~35% for pg-sz=2MB|1GB. The
first goes from around 8GBps to 11GBps and the second from 32GBps to 44
GBPs.
[ankur.a.arora@oracle.com: move the unit computation and make it a const
Link: https://lkml.kernel.org/r/20260108060406.1693853-1-ankur.a.arora@oracle.com
Link: https://lkml.kernel.org/r/20260107072009.1615991-8-ankur.a.arora@oracle.com
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Konrad Rzessutek Wilk <konrad.wilk@oracle.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Li Zhe <lizhe.67@bytedance.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Raghavendra K T <raghavendra.kt@amd.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Define clear_user_highpages() which uses the range clearing primitive,
clear_user_pages(). We can safely use this when CONFIG_HIGHMEM is
disabled and if the architecture does not have clear_user_highpage.
The first is needed to ensure that contiguous page ranges stay contiguous
which precludes intermediate maps via HIGMEM. The second, because if the
architecture has clear_user_highpage(), it likely needs flushing magic
when clearing the page, magic that we aren't privy to.
For both of those cases, just fallback to a loop around
clear_user_highpage().
Link: https://lkml.kernel.org/r/20260107072009.1615991-4-ankur.a.arora@oracle.com
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Konrad Rzessutek Wilk <konrad.wilk@oracle.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Li Zhe <lizhe.67@bytedance.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Raghavendra K T <raghavendra.kt@amd.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Introduce clear_pages(), to be overridden by architectures that support
more efficient clearing of consecutive pages.
Also introduce clear_user_pages(), however, we will not expect this
function to be overridden anytime soon.
As we do for clear_user_page(), define clear_user_pages() only if the
architecture does not define clear_user_highpage().
That is because if the architecture does define clear_user_highpage(),
then it likely needs some flushing magic when clearing user pages or
highpages. This means we can get away without defining
clear_user_pages(), since, much like its single page sibling, its only
potential user is the generic clear_user_highpages() which should instead
be using clear_user_highpage().
Link: https://lkml.kernel.org/r/20260107072009.1615991-3-ankur.a.arora@oracle.com
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Konrad Rzessutek Wilk <konrad.wilk@oracle.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Li Zhe <lizhe.67@bytedance.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Raghavendra K T <raghavendra.kt@amd.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "mm: folio_zero_user: clear page ranges", v11.
This series adds clearing of contiguous page ranges for hugepages.
The series improves on the current discontiguous clearing approach in two
ways:
- clear pages in a contiguous fashion.
- use batched clearing via clear_pages() wherever exposed.
The first is useful because it allows us to make much better use of
hardware prefetchers.
The second, enables advertising the real extent to the processor. Where
specific instructions support it (ex. string instructions on x86; "mops"
on arm64 etc), a processor can optimize based on this because, instead of
seeing a sequence of 8-byte stores, or a sequence of 4KB pages, it sees a
larger unit being operated on.
For instance, AMD Zen uarchs (for extents larger than LLC-size) switch to
a mode where they start eliding cacheline allocation. This is helpful not
just because it results in higher bandwidth, but also because now the
cache is not evicting useful cachelines and replacing them with zeroes.
Demand faulting a 64GB region shows performance improvement:
$ perf bench mem mmap -p $pg-sz -f demand -s 64GB -l 5
baseline +series
(GBps +- %stdev) (GBps +- %stdev)
pg-sz=2MB 11.76 +- 1.10% 25.34 +- 1.18% [*] +115.47% preempt=*
pg-sz=1GB 24.85 +- 2.41% 39.22 +- 2.32% + 57.82% preempt=none|voluntary
pg-sz=1GB (similar) 52.73 +- 0.20% [#] +112.19% preempt=full|lazy
[*] This improvement is because switching to sequential clearing
allows the hardware prefetchers to do a much better job.
[#] For pg-sz=1GB a large part of the improvement is because of the
cacheline elision mentioned above. preempt=full|lazy improves upon
that because, not needing explicit invocations of cond_resched() to
ensure reasonable preemption latency, it can clear the full extent
as a single unit. In comparison the maximum extent used for
preempt=none|voluntary is PROCESS_PAGES_NON_PREEMPT_BATCH (32MB).
When provided the full extent the processor forgoes allocating
cachelines on this path almost entirely.
(The hope is that eventually, in the fullness of time, the lazy
preemption model will be able to do the same job that none or
voluntary models are used for, allowing us to do away with
cond_resched().)
Raghavendra also tested previous version of the series on AMD Genoa and
sees similar improvement [1] with preempt=lazy.
$ perf bench mem map -p $page-size -f populate -s 64GB -l 10
base patched change
pg-sz=2MB 12.731939 GB/sec 26.304263 GB/sec 106.6%
pg-sz=1GB 26.232423 GB/sec 61.174836 GB/sec 133.2%
This patch (of 8):
Let's drop all variants that effectively map to clear_page() and provide
it in a generic variant instead.
We'll use the macro clear_user_page to indicate whether an architecture
provides it's own variant.
Also, clear_user_page() is only called from the generic variant of
clear_user_highpage(), so define it only if the architecture does not
provide a clear_user_highpage(). And, for simplicity define it in
linux/highmem.h.
Note that for parisc, clear_page() and clear_user_page() map to
clear_page_asm(), so we can just get rid of the custom clear_user_page()
implementation. There is a clear_user_page_asm() function on parisc, that
seems to be unused. Not sure what's up with that.
Link: https://lkml.kernel.org/r/20260107072009.1615991-1-ankur.a.arora@oracle.com
Link: https://lkml.kernel.org/r/20260107072009.1615991-2-ankur.a.arora@oracle.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Co-developed-by: Ankur Arora <ankur.a.arora@oracle.com>
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ankur Arora <ankur.a.arora@oracle.com>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Konrad Rzessutek Wilk <konrad.wilk@oracle.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Li Zhe <lizhe.67@bytedance.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Raghavendra K T <raghavendra.kt@amd.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Despite recent efforts to prevent lazy_mmu sections from nesting, it
remains difficult to ensure that it never occurs - and in fact it does
occur on arm64 in certain situations (CONFIG_DEBUG_PAGEALLOC). Commit
1ef3095b1405 ("arm64/mm: Permit lazy_mmu_mode to be nested") made nesting
tolerable on arm64, but without truly supporting it: the inner call to
leave() disables the batching optimisation before the outer section ends.
This patch actually enables lazy_mmu sections to nest by tracking the
nesting level in task_struct, in a similar fashion to e.g.
pagefault_{enable,disable}(). This is fully handled by the generic
lazy_mmu helpers that were recently introduced.
lazy_mmu sections were not initially intended to nest, so we need to
clarify the semantics w.r.t. the arch_*_lazy_mmu_mode() callbacks. This
patch takes the following approach:
* The outermost calls to lazy_mmu_mode_{enable,disable}() trigger
calls to arch_{enter,leave}_lazy_mmu_mode() - this is unchanged.
* Nested calls to lazy_mmu_mode_{enable,disable}() are not forwarded
to the arch via arch_{enter,leave} - lazy MMU remains enabled so
the assumption is that these callbacks are not relevant. However,
existing code may rely on a call to disable() to flush any batched
state, regardless of nesting. arch_flush_lazy_mmu_mode() is
therefore called in that situation.
A separate interface was recently introduced to temporarily pause the lazy
MMU mode: lazy_mmu_mode_{pause,resume}(). pause() fully exits the mode
*regardless of the nesting level*, and resume() restores the mode at the
same nesting level.
pause()/resume() are themselves allowed to nest, so we actually store two
nesting levels in task_struct: enable_count and pause_count. A new helper
is_lazy_mmu_mode_active() is introduced to determine whether we are
currently in lazy MMU mode; this will be used in subsequent patches to
replace the various ways arch's currently track whether the mode is
enabled.
In summary (enable/pause represent the values *after* the call):
lazy_mmu_mode_enable() -> arch_enter() enable=1 pause=0
lazy_mmu_mode_enable() -> ø enable=2 pause=0
lazy_mmu_mode_pause() -> arch_leave() enable=2 pause=1
lazy_mmu_mode_resume() -> arch_enter() enable=2 pause=0
lazy_mmu_mode_disable() -> arch_flush() enable=1 pause=0
lazy_mmu_mode_disable() -> arch_leave() enable=0 pause=0
Note: is_lazy_mmu_mode_active() is added to <linux/sched.h> to allow
arch headers included by <linux/pgtable.h> to use it.
Link: https://lkml.kernel.org/r/20251215150323.2218608-10-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Juegren Gross <jgross@suse.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The lazy MMU mode cannot be used in interrupt context. This is documented
in <linux/pgtable.h>, but isn't consistently handled across architectures.
arm64 ensures that calls to lazy_mmu_mode_* have no effect in interrupt
context, because such calls do occur in certain configurations - see
commit b81c688426a9 ("arm64/mm: Disable barrier batching in interrupt
contexts"). Other architectures do not check this situation, most likely
because it hasn't occurred so far.
Let's handle this in the new generic lazy_mmu layer, in the same fashion
as arm64: bail out of lazy_mmu_mode_* if in_interrupt(). Also remove the
arm64 handling that is now redundant.
Both arm64 and x86/Xen also ensure that any lazy MMU optimisation is
disabled while in interrupt (see queue_pte_barriers() and
xen_get_lazy_mode() respectively). This will be handled in the generic
layer in a subsequent patch.
Link: https://lkml.kernel.org/r/20251215150323.2218608-9-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Juegren Gross <jgross@suse.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The implementation of the lazy MMU mode is currently entirely
arch-specific; core code directly calls arch helpers:
arch_{enter,leave}_lazy_mmu_mode().
We are about to introduce support for nested lazy MMU sections. As things
stand we'd have to duplicate that logic in every arch implementing
lazy_mmu - adding to a fair amount of logic already duplicated across
lazy_mmu implementations.
This patch therefore introduces a new generic layer that calls the
existing arch_* helpers. Two pair of calls are introduced:
* lazy_mmu_mode_enable() ... lazy_mmu_mode_disable()
This is the standard case where the mode is enabled for a given
block of code by surrounding it with enable() and disable()
calls.
* lazy_mmu_mode_pause() ... lazy_mmu_mode_resume()
This is for situations where the mode is temporarily disabled
by first calling pause() and then resume() (e.g. to prevent any
batching from occurring in a critical section).
The documentation in <linux/pgtable.h> will be updated in a subsequent
patch.
No functional change should be introduced at this stage. The
implementation of enable()/resume() and disable()/pause() is currently
identical, but nesting support will change that.
Most of the call sites have been updated using the following Coccinelle
script:
@@
@@
{
...
- arch_enter_lazy_mmu_mode();
+ lazy_mmu_mode_enable();
...
- arch_leave_lazy_mmu_mode();
+ lazy_mmu_mode_disable();
...
}
@@
@@
{
...
- arch_leave_lazy_mmu_mode();
+ lazy_mmu_mode_pause();
...
- arch_enter_lazy_mmu_mode();
+ lazy_mmu_mode_resume();
...
}
A couple of notes regarding x86:
* Xen is currently the only case where explicit handling is required
for lazy MMU when context-switching. This is purely an
implementation detail and using the generic lazy_mmu_mode_*
functions would cause trouble when nesting support is introduced,
because the generic functions must be called from the current task.
For that reason we still use arch_leave() and arch_enter() there.
* x86 calls arch_flush_lazy_mmu_mode() unconditionally in a few
places, but only defines it if PARAVIRT_XXL is selected, and we
are removing the fallback in <linux/pgtable.h>. Add a new fallback
definition to <asm/pgtable.h> to keep things building.
Link: https://lkml.kernel.org/r/20251215150323.2218608-8-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand (Red Hat) <david@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Juegren Gross <jgross@suse.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Architectures currently opt in for implementing lazy_mmu helpers by
defining __HAVE_ARCH_ENTER_LAZY_MMU_MODE.
In preparation for introducing a generic lazy_mmu layer that will require
storage in task_struct, let's switch to a cleaner approach: instead of
defining a macro, select a CONFIG option.
This patch introduces CONFIG_ARCH_HAS_LAZY_MMU_MODE and has each arch
select it when it implements lazy_mmu helpers.
__HAVE_ARCH_ENTER_LAZY_MMU_MODE is removed and <linux/pgtable.h> relies on
the new CONFIG instead.
On x86, lazy_mmu helpers are only implemented if PARAVIRT_XXL is selected.
This creates some complications in arch/x86/boot/, because a few files
manually undefine PARAVIRT* options. As a result <asm/paravirt.h> does
not define the lazy_mmu helpers, but this breaks the build as
<linux/pgtable.h> only defines them if !CONFIG_ARCH_HAS_LAZY_MMU_MODE.
There does not seem to be a clean way out of this - let's just undefine
that new CONFIG too.
Link: https://lkml.kernel.org/r/20251215150323.2218608-7-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Acked-by: Andreas Larsson <andreas@gaisler.com> [sparc]
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand (Red Hat) <david@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Juegren Gross <jgross@suse.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
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The lazy MMU mode documentation makes clear that an implementation should
not assume that preemption is disabled or any lock is held upon entry to
the mode; however it says nothing about what code using the lazy MMU
interface should expect.
In practice sleeping is forbidden (for generic code) while the lazy MMU
mode is active: say it explicitly.
Link: https://lkml.kernel.org/r/20251215150323.2218608-6-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David S. Miller <davem@davemloft.net>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Juegren Gross <jgross@suse.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
HIPPI has not been relevant for over two decades. It was rapidly
eclipsed by Fibre Channel, and even when it was new, it was
confined to very high-end hardware. The HIPPI code has only
received tree-wide changes and fixes by inspection in the entire
Git history. Remove HIPPI support and the rrunner HIPPI driver,
and move the former maintainer to the CREDITS file. Keep the
include/uapi/linux/if_hippi.h header because it is used by the TUN
code, and to avoid breaking userspace, however unlikely that may be.
Signed-off-by: Ethan Nelson-Moore <enelsonmoore@gmail.com>
Link: https://patch.msgid.link/20260119022451.22344-1-enelsonmoore@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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|
tcp_rate_skb_delivered() is only called from tcp_input.c.
Move it there and make it static.
Both gcc and clang are (auto)inlining it, TCP performance
is increased at a small space cost.
$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 0/2 grow/shrink: 3/0 up/down: 509/-187 (322)
Function old new delta
tcp_sacktag_walk 1682 1867 +185
tcp_ack 5230 5405 +175
tcp_shifted_skb 437 586 +149
__pfx_tcp_rate_skb_delivered 16 - -16
tcp_rate_skb_delivered 171 - -171
Total: Before=22566192, After=22566514, chg +0.00%
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Link: https://patch.msgid.link/20260118123204.2315993-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Pavel Begunkov says:
====================
Add support for providers with large rx buffer
Many modern NICs support configurable receive buffer lengths, and zcrx and
memory providers can use buffers larger than 4K to improve performance.
When paired with hw-gro larger rx buffer sizes can drastically reduce
the number of buffers traversing the stack and save a lot of processing
time. It also allows to give to users larger contiguous chunks of data.
Single stream benchmarks showed up to ~30% CPU util improvement.
E.g. comparison for 4K vs 32K buffers using a 200Gbit NIC:
packets=23987040 (MB=2745098), rps=199559 (MB/s=22837)
CPU %usr %nice %sys %iowait %irq %soft %idle
0 1.53 0.00 27.78 2.72 1.31 66.45 0.22
packets=24078368 (MB=2755550), rps=200319 (MB/s=22924)
CPU %usr %nice %sys %iowait %irq %soft %idle
0 0.69 0.00 8.26 31.65 1.83 57.00 0.57
This series adds net infrastructure for memory providers configuring
the size and implements it for bnxt. It's an opt-in feature for drivers,
they should advertise support for the parameter in the qops and must check
if the hardware supports the given size. It's limited to memory providers
as it drastically simplifies implementation. It doesn't affect the fast
path zcrx uAPI, and the user exposed parameter is defined in zcrx terms,
which allows it to be flexible and adjusted in the future.
A liburing example can be found at [2]
full branch:
[1] https://github.com/isilence/linux.git zcrx/large-buffers-v8
Liburing example:
[2] https://github.com/isilence/liburing.git zcrx/rx-buf-len
* tag 'net-queue-rx-buf-len-v9' of https://github.com/isilence/linux:
io_uring/zcrx: document area chunking parameter
selftests: iou-zcrx: test large chunk sizes
eth: bnxt: support qcfg provided rx page size
eth: bnxt: adjust the fill level of agg queues with larger buffers
eth: bnxt: store rx buffer size per queue
net: pass queue rx page size from memory provider
net: add bare bone queue configs
net: reduce indent of struct netdev_queue_mgmt_ops members
net: memzero mp params when closing a queue
====================
Link: https://patch.msgid.link/
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
|
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This reverts commit 77b9c4a438fc66e2ab004c411056b3fb71a54f2c, reversing
changes made to 4515ec4ad58a37e70a9e1256c0b993958c9b7497:
931420a2fc36 ("selftests/net: Add netkit container tests")
ab771c938d9a ("selftests/net: Make NetDrvContEnv support queue leasing")
6be87fbb2776 ("selftests/net: Add env for container based tests")
61d99ce3dfc2 ("selftests/net: Add bpf skb forwarding program")
920da3634194 ("netkit: Add xsk support for af_xdp applications")
eef51113f8af ("netkit: Add netkit notifier to check for unregistering devices")
b5ef109d22d4 ("netkit: Implement rtnl_link_ops->alloc and ndo_queue_create")
b5c3fa4a0b16 ("netkit: Add single device mode for netkit")
0073d2fd679d ("xsk: Proxy pool management for leased queues")
1ecea95dd3b5 ("xsk: Extend xsk_rcv_check validation")
804bf334d08a ("net: Proxy netdev_queue_get_dma_dev for leased queues")
0caa9a8ddec3 ("net: Proxy net_mp_{open,close}_rxq for leased queues")
ff8889ff9107 ("net, ethtool: Disallow leased real rxqs to be resized")
9e2103f36110 ("net: Add lease info to queue-get response")
31127deddef4 ("net: Implement netdev_nl_queue_create_doit")
a5546e18f77c ("net: Add queue-create operation")
The series will conflict with io_uring work, and the code needs more
polish.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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A kernel function bpf_foo marked with KF_IMPLICIT_ARGS flag is
expected to have two associated types in BTF:
* `bpf_foo` with a function prototype that omits implicit arguments
* `bpf_foo_impl` with a function prototype that matches the kernel
declaration of `bpf_foo`, but doesn't have a ksym associated with
its name
In order to support kfuncs with implicit arguments, the verifier has
to know how to resolve a call of `bpf_foo` to the correct BTF function
prototype and address.
To implement this, in add_kfunc_call() kfunc flags are checked for
KF_IMPLICIT_ARGS. For such kfuncs a BTF func prototype is adjusted to
the one found for `bpf_foo_impl` (func_name + "_impl" suffix, by
convention) function in BTF.
This effectively changes the signature of the `bpf_foo` kfunc in the
context of verification: from one without implicit args to the one
with full argument list.
The values of implicit arguments by design are provided by the
verifier, and so they can only be of particular types. In this patch
the only allowed implicit arg type is a pointer to struct
bpf_prog_aux.
In order for the verifier to correctly set an implicit bpf_prog_aux
arg value at runtime, is_kfunc_arg_prog() is extended to check for the
arg type. At a point when prog arg is determined in check_kfunc_args()
the kfunc with implicit args already has a prototype with full
argument list, so the existing value patch mechanism just works.
If a new kfunc with KF_IMPLICIT_ARG is declared for an existing kfunc
that uses a __prog argument (a legacy case), the prototype
substitution works in exactly the same way, assuming the kfunc follows
the _impl naming convention. The difference is only in how _impl
prototype is added to the BTF, which is not the verifier's
concern. See a subsequent resolve_btfids patch for details.
__prog suffix is still supported at this point, but will be removed in
a subsequent patch, after current users are moved to KF_IMPLICIT_ARGS.
Introduction of KF_IMPLICIT_ARGS revealed an issue with zero-extension
tracking, because an explicit rX = 0 in place of the verifier-supplied
argument is now absent if the arg is implicit (the BPF prog doesn't
pass a dummy NULL anymore). To mitigate this, reset the subreg_def of
all caller saved registers in check_kfunc_call() [1].
[1] https://lore.kernel.org/bpf/b4a760ef828d40dac7ea6074d39452bb0dc82caa.camel@gmail.com/
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260120222638.3976562-4-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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btf_kfunc_id_set_contains() is called by fetch_kfunc_meta() in the BPF
verifier to get the kfunc flags stored in the .BTF_ids ELF section.
If it returns NULL instead of a valid pointer, it's interpreted as an
illegal kfunc usage failing the verification.
There are two potential reasons for btf_kfunc_id_set_contains() to
return NULL:
1. Provided kfunc BTF id is not present in relevant kfunc id sets.
2. The kfunc is not allowed, as determined by the program type
specific filter [1].
The filter functions accept a pointer to `struct bpf_prog`, so they
might implicitly depend on earlier stages of verification, when
bpf_prog members are set.
For example, bpf_qdisc_kfunc_filter() in linux/net/sched/bpf_qdisc.c
inspects prog->aux->st_ops [2], which is initialized in:
check_attach_btf_id() -> check_struct_ops_btf_id()
So far this hasn't been an issue, because fetch_kfunc_meta() is the
only caller of btf_kfunc_id_set_contains().
However in subsequent patches of this series it is necessary to
inspect kfunc flags earlier in BPF verifier, in the add_kfunc_call().
To resolve this, refactor btf_kfunc_id_set_contains() into two
interface functions:
* btf_kfunc_flags() that simply returns pointer to kfunc_flags
without applying the filters
* btf_kfunc_is_allowed() that both checks for kfunc_flags existence
(which is a requirement for a kfunc to be allowed) and applies the
prog filters
See [3] for the previous version of this patch.
[1] https://lore.kernel.org/all/20230519225157.760788-7-aditi.ghag@isovalent.com/
[2] https://lore.kernel.org/all/20250409214606.2000194-4-ameryhung@gmail.com/
[3] https://lore.kernel.org/bpf/20251029190113.3323406-3-ihor.solodrai@linux.dev/
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260120222638.3976562-2-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull misc fixes from Andrew Morton:
- A patch series from David Hildenbrand which fixes a few things
related to hugetlb PMD sharing
- The remainder are singletons, please see their changelogs for details
* tag 'mm-hotfixes-stable-2026-01-20-13-09' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
mm: restore per-memcg proactive reclaim with !CONFIG_NUMA
mm/kfence: fix potential deadlock in reboot notifier
Docs/mm/allocation-profiling: describe sysctrl limitations in debug mode
mm: do not copy page tables unnecessarily for VM_UFFD_WP
mm/hugetlb: fix excessive IPI broadcasts when unsharing PMD tables using mmu_gather
mm/rmap: fix two comments related to huge_pmd_unshare()
mm/hugetlb: fix two comments related to huge_pmd_unshare()
mm/hugetlb: fix hugetlb_pmd_shared()
mm: remove unnecessary and incorrect mmap lock assert
x86/kfence: avoid writing L1TF-vulnerable PTEs
mm/vma: do not leak memory when .mmap_prepare swaps the file
migrate: correct lock ordering for hugetlb file folios
panic: only warn about deprecated panic_print on write access
fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes()
mm: take into account mm_cid size for mm_struct static definitions
mm: rename cpu_bitmap field to flexible_array
mm: add missing static initializer for init_mm::mm_cid.lock
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Add Nova Lake (NVL) audio Device ID
The ID will be used by HDA legacy, SOF audio stack and the driver
to determine which audio stack should be used (intel-dsp-config).
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Liam Girdwood <liam.r.girdwood@intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20260120193507.14019-2-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
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MT7987
Add thermal controller definition for MT7987.
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20251223175710.25850-2-linux@fw-web.de
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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Directly returning delegations on close when over the watermark is
rather suboptimal as these delegations are much more likely to be reused
than those that have been unused for a long time. Switch to returning
unused delegations from a new LRU list when we are above the threshold and
there are reclaimable delegations instead.
Pass over referenced delegations during the first pass to give delegations
that aren't in active used by frequently used for stat() or similar another
chance to not be instantly reclaimed. This scheme works the same as the
referenced flags in the VFS inode and dentry caches.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
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Searching for returnable delegations in the per-server delegations list
can be very expensive. While commit e04bbf6b1bbe ("NFS: Avoid quadratic
search when freeing delegations.") reduced the overhead a bit, the
fact that all the non-returnable delegations have to be searched limits
the amount of optimizations that can be done.
Fix this by introducing a separate list that only contains delegations
scheduled for return.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
|
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Add LVTS thermal controller binding for MediaTek MT8196.
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: Frank Wunderlich <frank-w@public-files.de>
Signed-off-by: Laura Nao <laura.nao@collabora.com>
Link: https://patch.msgid.link/20251125-mt8196-lvts-v4-v5-1-6db7eb903fb7@collabora.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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Currently, reset_idmap_scratch() performs a 4.7KB memset() in every
states_equal() call. Optimize this by using a counter to track used
ID mappings, replacing the O(N) memset() with an O(1) reset and
bounding the search loop in check_ids().
Signed-off-by: Qiliang Yuan <realwujing@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20260120023234.77673-1-realwujing@gmail.com
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Merge series from Claudiu <claudiu.beznea@tuxon.dev>:
This series adds cleanups for the Renesas RZ SSI driver.
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git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux
Pull dma-mapping fixes from Marek Szyprowski:
- minor fixes for the corner cases of the SWIOTLB pool management
(Robin Murphy)
* tag 'dma-mapping-6.19-2026-01-20' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux:
dma/pool: Avoid allocating redundant pools
mm_zone: Generalise has_managed_dma()
dma/pool: Improve pool lookup
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Merge series from Abdurrahman Hussain <abdurrahman@nexthop.ai>:
Additionally, make interrupts optional to allow the driver to fall back
to its existing polling mode on systems where interrupts are either missing
or broken.
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Commit ab04b530e7e8 ("mm: introduce copy-on-fork VMAs and make
VM_MAYBE_GUARD one") aggregates flags checks in vma_needs_copy(),
including VM_UFFD_WP.
However in doing so, it incorrectly performed this check against src_vma.
This check was done on the assumption that all relevant flags are copied
upon fork.
However the userfaultfd logic is very innovative in that it implements
custom logic on fork in dup_userfaultfd(), including a rather well hidden
case where lacking UFFD_FEATURE_EVENT_FORK causes VM_UFFD_WP to not be
propagated to the destination VMA.
And indeed, vma_needs_copy(), prior to this patch, did check this property
on dst_vma, not src_vma.
Since all the other relevant flags are copied on fork, we can simply fix
this by checking against dst_vma.
While we're here, we fix a comment against VM_COPY_ON_FORK (noting that it
did indeed already reference dst_vma) to make it abundantly clear that we
must check against the destination VMA.
Link: https://lkml.kernel.org/r/20260114110006.1047071-1-lorenzo.stoakes@oracle.com
Fixes: ab04b530e7e8 ("mm: introduce copy-on-fork VMAs and make VM_MAYBE_GUARD one")
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reported-by: Chris Mason <clm@meta.com>
Closes: https://lore.kernel.org/all/20260113231257.3002271-1-clm@meta.com/
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Acked-by: Pedro Falcato <pfalcato@suse.de>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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mmu_gather
As reported, ever since commit 1013af4f585f ("mm/hugetlb: fix
huge_pmd_unshare() vs GUP-fast race") we can end up in some situations
where we perform so many IPI broadcasts when unsharing hugetlb PMD page
tables that it severely regresses some workloads.
In particular, when we fork()+exit(), or when we munmap() a large
area backed by many shared PMD tables, we perform one IPI broadcast per
unshared PMD table.
There are two optimizations to be had:
(1) When we process (unshare) multiple such PMD tables, such as during
exit(), it is sufficient to send a single IPI broadcast (as long as
we respect locking rules) instead of one per PMD table.
Locking prevents that any of these PMD tables could get reused before
we drop the lock.
(2) When we are not the last sharer (> 2 users including us), there is
no need to send the IPI broadcast. The shared PMD tables cannot
become exclusive (fully unshared) before an IPI will be broadcasted
by the last sharer.
Concurrent GUP-fast could walk into a PMD table just before we
unshared it. It could then succeed in grabbing a page from the
shared page table even after munmap() etc succeeded (and supressed
an IPI). But there is not difference compared to GUP-fast just
sleeping for a while after grabbing the page and re-enabling IRQs.
Most importantly, GUP-fast will never walk into page tables that are
no-longer shared, because the last sharer will issue an IPI
broadcast.
(if ever required, checking whether the PUD changed in GUP-fast
after grabbing the page like we do in the PTE case could handle
this)
So let's rework PMD sharing TLB flushing + IPI sync to use the mmu_gather
infrastructure so we can implement these optimizations and demystify the
code at least a bit. Extend the mmu_gather infrastructure to be able to
deal with our special hugetlb PMD table sharing implementation.
To make initialization of the mmu_gather easier when working on a single
VMA (in particular, when dealing with hugetlb), provide
tlb_gather_mmu_vma().
We'll consolidate the handling for (full) unsharing of PMD tables in
tlb_unshare_pmd_ptdesc() and tlb_flush_unshared_tables(), and track
in "struct mmu_gather" whether we had (full) unsharing of PMD tables.
Because locking is very special (concurrent unsharing+reuse must be
prevented), we disallow deferring flushing to tlb_finish_mmu() and instead
require an explicit earlier call to tlb_flush_unshared_tables().
From hugetlb code, we call huge_pmd_unshare_flush() where we make sure
that the expected lock protecting us from concurrent unsharing+reuse is
still held.
Check with a VM_WARN_ON_ONCE() in tlb_finish_mmu() that
tlb_flush_unshared_tables() was properly called earlier.
Document it all properly.
Notes about tlb_remove_table_sync_one() interaction with unsharing:
There are two fairly tricky things:
(1) tlb_remove_table_sync_one() is a NOP on architectures without
CONFIG_MMU_GATHER_RCU_TABLE_FREE.
Here, the assumption is that the previous TLB flush would send an
IPI to all relevant CPUs. Careful: some architectures like x86 only
send IPIs to all relevant CPUs when tlb->freed_tables is set.
The relevant architectures should be selecting
MMU_GATHER_RCU_TABLE_FREE, but x86 might not do that in stable
kernels and it might have been problematic before this patch.
Also, the arch flushing behavior (independent of IPIs) is different
when tlb->freed_tables is set. Do we have to enlighten them to also
take care of tlb->unshared_tables? So far we didn't care, so
hopefully we are fine. Of course, we could be setting
tlb->freed_tables as well, but that might then unnecessarily flush
too much, because the semantics of tlb->freed_tables are a bit
fuzzy.
This patch changes nothing in this regard.
(2) tlb_remove_table_sync_one() is not a NOP on architectures with
CONFIG_MMU_GATHER_RCU_TABLE_FREE that actually don't need a sync.
Take x86 as an example: in the common case (!pv, !X86_FEATURE_INVLPGB)
we still issue IPIs during TLB flushes and don't actually need the
second tlb_remove_table_sync_one().
This optimized can be implemented on top of this, by checking e.g., in
tlb_remove_table_sync_one() whether we really need IPIs. But as
described in (1), it really must honor tlb->freed_tables then to
send IPIs to all relevant CPUs.
Notes on TLB flushing changes:
(1) Flushing for non-shared PMD tables
We're converting from flush_hugetlb_tlb_range() to
tlb_remove_huge_tlb_entry(). Given that we properly initialize the
MMU gather in tlb_gather_mmu_vma() to be hugetlb aware, similar to
__unmap_hugepage_range(), that should be fine.
(2) Flushing for shared PMD tables
We're converting from various things (flush_hugetlb_tlb_range(),
tlb_flush_pmd_range(), flush_tlb_range()) to tlb_flush_pmd_range().
tlb_flush_pmd_range() achieves the same that
tlb_remove_huge_tlb_entry() would achieve in these scenarios.
Note that tlb_remove_huge_tlb_entry() also calls
__tlb_remove_tlb_entry(), however that is only implemented on
powerpc, which does not support PMD table sharing.
Similar to (1), tlb_gather_mmu_vma() should make sure that TLB
flushing keeps on working as expected.
Further, note that the ptdesc_pmd_pts_dec() in huge_pmd_share() is not a
concern, as we are holding the i_mmap_lock the whole time, preventing
concurrent unsharing. That ptdesc_pmd_pts_dec() usage will be removed
separately as a cleanup later.
There are plenty more cleanups to be had, but they have to wait until
this is fixed.
[david@kernel.org: fix kerneldoc]
Link: https://lkml.kernel.org/r/f223dd74-331c-412d-93fc-69e360a5006c@kernel.org
Link: https://lkml.kernel.org/r/20251223214037.580860-5-david@kernel.org
Fixes: 1013af4f585f ("mm/hugetlb: fix huge_pmd_unshare() vs GUP-fast race")
Signed-off-by: David Hildenbrand (Red Hat) <david@kernel.org>
Reported-by: Uschakow, Stanislav" <suschako@amazon.de>
Closes: https://lore.kernel.org/all/4d3878531c76479d9f8ca9789dc6485d@amazon.de/
Tested-by: Laurence Oberman <loberman@redhat.com>
Acked-by: Harry Yoo <harry.yoo@oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "mm/hugetlb: fixes for PMD table sharing (incl. using
mmu_gather)", v3.
One functional fix, one performance regression fix, and two related
comment fixes.
I cleaned up my prototype I recently shared [1] for the performance fix,
deferring most of the cleanups I had in the prototype to a later point.
While doing that I identified the other things.
The goal of this patch set is to be backported to stable trees "fairly"
easily. At least patch #1 and #4.
Patch #1 fixes hugetlb_pmd_shared() not detecting any sharing
Patch #2 + #3 are simple comment fixes that patch #4 interacts with.
Patch #4 is a fix for the reported performance regression due to excessive
IPI broadcasts during fork()+exit().
The last patch is all about TLB flushes, IPIs and mmu_gather.
Read: complicated
There are plenty of cleanups in the future to be had + one reasonable
optimization on x86. But that's all out of scope for this series.
Runtime tested, with a focus on fixing the performance regression using
the original reproducer [2] on x86.
This patch (of 4):
We switched from (wrongly) using the page count to an independent shared
count. Now, shared page tables have a refcount of 1 (excluding
speculative references) and instead use ptdesc->pt_share_count to identify
sharing.
We didn't convert hugetlb_pmd_shared(), so right now, we would never
detect a shared PMD table as such, because sharing/unsharing no longer
touches the refcount of a PMD table.
Page migration, like mbind() or migrate_pages() would allow for migrating
folios mapped into such shared PMD tables, even though the folios are not
exclusive. In smaps we would account them as "private" although they are
"shared", and we would be wrongly setting the PM_MMAP_EXCLUSIVE in the
pagemap interface.
Fix it by properly using ptdesc_pmd_is_shared() in hugetlb_pmd_shared().
Link: https://lkml.kernel.org/r/20251223214037.580860-1-david@kernel.org
Link: https://lkml.kernel.org/r/20251223214037.580860-2-david@kernel.org
Link: https://lore.kernel.org/all/8cab934d-4a56-44aa-b641-bfd7e23bd673@kernel.org/ [1]
Link: https://lore.kernel.org/all/8cab934d-4a56-44aa-b641-bfd7e23bd673@kernel.org/ [2]
Fixes: 59d9094df3d7 ("mm: hugetlb: independent PMD page table shared count")
Signed-off-by: David Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Tested-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Tested-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Oscar Salvador <osalvador@suse.de>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Uschakow, Stanislav" <suschako@amazon.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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When multiple io_uring rings poll on the same NVMe queue, one ring can
find completions belonging to another ring. The current code always
uses task_work to handle this, but this adds overhead for the common
single-ring case.
This patch passes the polling io_ring_ctx through io_comp_batch's new
poll_ctx field. In io_do_iopoll(), the polling ring's context is stored
in iob.poll_ctx before calling the iopoll callbacks.
In nvme_uring_cmd_end_io(), we now compare iob->poll_ctx with the
request's owning io_ring_ctx (via io_uring_cmd_ctx_handle()). If they
match (local context), we complete inline with io_uring_cmd_done32().
If they differ (remote context) or iob is NULL (non-iopoll path), we
use task_work as before.
This optimization eliminates task_work scheduling overhead for the
common case where a ring polls and finds its own completions.
~10% IOPS improvement is observed in the following benchmark:
fio/t/io_uring -b512 -d128 -c32 -s32 -p1 -F1 -O0 -P1 -u1 -n1 /dev/ng0n1
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add a third parameter 'const struct io_comp_batch *' to the rq_end_io_fn
callback signature. This allows end_io handlers to access the completion
batch context when requests are completed via blk_mq_end_request_batch().
The io_comp_batch is passed from blk_mq_end_request_batch(), while NULL
is passed from __blk_mq_end_request() and blk_mq_put_rq_ref() which don't
have batch context.
This infrastructure change enables drivers to detect whether they're
being called from a batched completion path (like iopoll) and access
additional context stored in the io_comp_batch.
Update all rq_end_io_fn implementations:
- block/blk-mq.c: blk_end_sync_rq
- block/blk-flush.c: flush_end_io, mq_flush_data_end_io
- drivers/nvme/host/ioctl.c: nvme_uring_cmd_end_io
- drivers/nvme/host/core.c: nvme_keep_alive_end_io
- drivers/nvme/host/pci.c: abort_endio, nvme_del_queue_end, nvme_del_cq_end
- drivers/nvme/target/passthru.c: nvmet_passthru_req_done
- drivers/scsi/scsi_error.c: eh_lock_door_done
- drivers/scsi/sg.c: sg_rq_end_io
- drivers/scsi/st.c: st_scsi_execute_end
- drivers/target/target_core_pscsi.c: pscsi_req_done
- drivers/md/dm-rq.c: end_clone_request
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/mani/mhi into char-misc-next
Manivannan writes:
MHI Host
--------
- Add support for loading dual ELF image format firmware to Qcom Trust
Management Engine Lit (TME-L) supported devices like QCC2072, which require
separate ELF header for SBL and WLAN firmware segments in a single firmware.
- Remove the MHI auto_queue feature support. This feature was added to offload
the queuing of buffers from the client drivers to the MHI stack, but it caused
a lot of race over the time. So remove this feature from the QRTR client
driver and also from the MHI stack/controller drivers.
- Move the .probe() and .remove() callbacks from driver level to bus level.
MHI Endpoint
------------
- Move the .probe() and .remove() callbacks from driver level to bus level.
* tag 'mhi-for-v6.20' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/mani/mhi:
bus: mhi: ep: Use bus callbacks for .probe() and .remove()
bus: mhi: host: Use bus callbacks for .probe() and .remove()
bus: mhi: host: Drop the auto_queue support
net: qrtr: Drop the MHI auto_queue feature for IPCR DL channels
mhi: host: Add support for loading dual ELF image format
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This was used only to allow the s5m RTC driver to deal with the alarm
IRQ. That driver now uses a different approach to acquire that IRQ, and
::irq_data doesn't need to be kept around anymore.
Signed-off-by: André Draszik <andre.draszik@linaro.org>
Link: https://patch.msgid.link/20260113-s5m-alarm-v3-3-855a19db1277@linaro.org
Signed-off-by: Lee Jones <lee@kernel.org>
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several netfilter compilation units rely on implicit includes
coming from nf_conntrack_proto_gre.h.
Clean this up and add the required dependencies where needed.
nf_conntrack.h requires net_generic() helper.
Place various gre/ppp/vlan includes to where they are needed.
Signed-off-by: Florian Westphal <fw@strlen.de>
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conntrack, xtables and nftables are distinct subsystems, don't use them
in other subystems.
Signed-off-by: Florian Westphal <fw@strlen.de>
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After the optimization to only perform one GC per jiffy, a new problem
was introduced. If more than 8 new connections are tracked per jiffy the
list won't be cleaned up fast enough possibly reaching the limit
wrongly.
In order to prevent this issue, only skip the GC if it was already
triggered during the same jiffy and the increment is lower than the
clean up limit. In addition, increase the clean up limit to 64
connections to avoid triggering GC too often and do more effective GCs.
This has been tested using a HTTP server and several
performance tools while having nft_connlimit/xt_connlimit or OVS limit
configured.
Output of slowhttptest + OVS limit at 52000 connections:
slow HTTP test status on 340th second:
initializing: 0
pending: 432
connected: 51998
error: 0
closed: 0
service available: YES
Fixes: d265929930e2 ("netfilter: nf_conncount: reduce unnecessary GC")
Reported-by: Aleksandra Rukomoinikova <ARukomoinikova@k2.cloud>
Closes: https://lore.kernel.org/netfilter/b2064e7b-0776-4e14-adb6-c68080987471@k2.cloud/
Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Signed-off-by: Florian Westphal <fw@strlen.de>
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