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Add documentation to describe agent_types attribute.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20250508230250.1186619-3-srinivas.pandruvada@linux.intel.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
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On our HDFS servers with 12 HDDs per server, a HDFS datanode[0] startup
involves scanning all files and caching their metadata (including dentries
and inodes) in memory. Each HDD contains approximately 2 million files,
resulting in a total of ~20 million cached dentries after initialization.
To minimize dentry reclamation, we set vfs_cache_pressure to 1. Despite
this configuration, memory pressure conditions can still trigger
reclamation of up to 50% of cached dentries, reducing the cache from 20
million to approximately 10 million entries. During the subsequent cache
rebuild period, any HDFS datanode restart operation incurs substantial
latency penalties until full cache recovery completes.
To maintain service stability, we need to preserve more dentries during
memory reclamation. The current minimum reclaim ratio (1/100 of total
dentries) remains too aggressive for our workload. This patch introduces
vfs_cache_pressure_denom for more granular cache pressure control. The
configuration [vfs_cache_pressure=1, vfs_cache_pressure_denom=10000]
effectively maintains the full 20 million dentry cache under memory
pressure, preventing datanode restart performance degradation.
Link: https://hadoop.apache.org/docs/r1.2.1/hdfs_design.html#NameNode+and+DataNodes [0]
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/20250511083624.9305-1-laoar.shao@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Describe the support for hybrid processors in intel_pstate, including
the CAS and EAS support, in the admin-guide documentation.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://patch.msgid.link/1935040.CQOukoFCf9@rjwysocki.net
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Conflicts:
Documentation/admin-guide/hw-vuln/index.rst
arch/x86/include/asm/cpufeatures.h
arch/x86/kernel/alternative.c
arch/x86/kernel/cpu/bugs.c
arch/x86/kernel/cpu/common.c
drivers/base/cpu.c
include/linux/cpu.h
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Prepare to resolve conflicts with an upstream series of fixes that conflict
with pending x86 changes:
6f5bf947bab0 Merge tag 'its-for-linus-20250509' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Fixes a typo in the root= parameter description, changing
"this a a" to "this is a".
Fixes: c0c1a7dcb6f5 ("init: move the nfs/cifs/ram special cases out of name_to_dev_t")
Signed-off-by: Petr Vaněk <arkamar@atlas.cz>
Link: https://lore.kernel.org/20250512110827.32530-1-arkamar@atlas.cz
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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With KHO in place, let's add documentation that describes what it is and
how to use it.
Link: https://lkml.kernel.org/r/20250509074635.3187114-17-changyuanl@google.com
Signed-off-by: Alexander Graf <graf@amazon.com>
Co-developed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Co-developed-by: Changyuan Lyu <changyuanl@google.com>
Signed-off-by: Changyuan Lyu <changyuanl@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anthony Yznaga <anthony.yznaga@oracle.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ashish Kalra <ashish.kalra@amd.com>
Cc: Ben Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Gowans <jgowans@amazon.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Rob Herring <robh@kernel.org>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Lendacky <thomas.lendacky@amd.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The MGLRU already supports reclaiming only from anonymous memory via the
/sys/kernel/debug/lru_gen interface. Now, memory.reclaim also supports
the swappiness=max parameter to enable reclaiming solely from anonymous
memory. To unify the semantics of proactive reclaiming from anonymous
folios, the max parameter is introduced.
[hezhongkun.hzk@bytedance.com: use strcmp instead of strncmp, if swappiness is not set, use the default value]
Link: https://lkml.kernel.org/r/20250507071057.3184240-1-hezhongkun.hzk@bytedance.com
[akpm@linux-foundation.org: tweak coding style]
Link: https://lkml.kernel.org/r/65181f7745d657d664d833c26d8a94cae40538b9.1745225696.git.hezhongkun.hzk@bytedance.com
Signed-off-by: Zhongkun He <hezhongkun.hzk@bytedance.com>
Acked-by: Muchun Song <muchun.song@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Yosry Ahmed <yosry.ahmed@linux.dev>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "add max arg to swappiness in memory.reclaim and lru_gen", v4.
This patchset adds max arg to swappiness in memory.reclaim and lru_gen for
anon only proactive memory reclaim.
With commit <68cd9050d871> ("mm: add swappiness= arg to memory.reclaim")
we can submit an additional swappiness=<val> argument to memory.reclaim.
It is very useful because we can dynamically adjust the reclamation ratio
based on the anonymous folios and file folios of each cgroup. For
example,when swappiness is set to 0, we only reclaim from file folios.
But we can not relciam memory just from anon folios.
This patchset introduces a new macro, SWAPPINESS_ANON_ONLY, defined as
MAX_SWAPPINESS + 1, represent the max arg semantics. It specifically
indicates that reclamation should occur only from anonymous pages.
Patch 1 adds swappiness=max arg to memory.reclaim suggested-by: Yosry
Ahmed
Patch 2 add more comments for cache_trim_mode from Johannes Weiner in [1].
Patch 3 add max arg to lru_gen for proactive memory reclaim in MGLRU. The
MGLRU already supports reclaiming exclusively from anonymous pages. This
patch formalizes that behavior by introducing a max parameter to represent
the corresponding semantics.
Patch 4 using SWAPPINESS_ANON_ONLY in MGLRU Using SWAPPINESS_ANON_ONLY
instead of MAX_SWAPPINESS + 1 to indicate reclaiming only from anonymous
pages makes the code more readable and explicit
Here is the previous discussion:
https://lore.kernel.org/all/20250314033350.1156370-1-hezhongkun.hzk@bytedance.com/
https://lore.kernel.org/all/20250312094337.2296278-1-hezhongkun.hzk@bytedance.com/
https://lore.kernel.org/all/20250318135330.3358345-1-hezhongkun.hzk@bytedance.com/
This patch (of 4):
With commit <68cd9050d871> ("mm: add swappiness= arg to memory.reclaim")
we can submit an additional swappiness=<val> argument to memory.reclaim.
It is very useful because we can dynamically adjust the reclamation ratio
based on the anonymous folios and file folios of each cgroup. For
example,when swappiness is set to 0, we only reclaim from file folios.
However,we have also encountered a new issue: when swappiness is set to
the MAX_SWAPPINESS, it may still only reclaim file folios.
So, we hope to add a new arg 'swappiness=max' in memory.reclaim where
proactive memory reclaim only reclaims from anonymous folios when
swappiness is set to max. The swappiness semantics from a user
perspective remain unchanged.
For example, something like this:
echo "2M swappiness=max" > /sys/fs/cgroup/memory.reclaim
will perform reclaim on the rootcg with a swappiness setting of 'max' (a
new mode) regardless of the file folios. Users have a more comprehensive
view of the application's memory distribution because there are many
metrics available. For example, if we find that a certain cgroup has a
large number of inactive anon folios, we can reclaim only those and skip
file folios, because with the zram/zswap, the IO tradeoff that
cache_trim_mode or other file first logic is making doesn't hold - file
refaults will cause IO, whereas anon decompression will not.
With this patch, the swappiness argument of memory.reclaim has a new
mode 'max', means reclaiming just from anonymous folios both in traditional
LRU and MGLRU.
Link: https://lkml.kernel.org/r/cover.1745225696.git.hezhongkun.hzk@bytedance.com
Link: https://lore.kernel.org/all/20250314141833.GA1316033@cmpxchg.org/ [1]
Link: https://lkml.kernel.org/r/519e12b9b1f8c31a01e228c8b4b91a2419684f77.1745225696.git.hezhongkun.hzk@bytedance.com
Signed-off-by: Zhongkun He <hezhongkun.hzk@bytedance.com>
Suggested-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Acked-by: Muchun Song <muchun.song@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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add more explanation in doc and commit message on O_NONBLOCK side-effects
(Johannes)
Link: https://lkml.kernel.org/r/20250506232833.3109790-1-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Greg Thelen <gthelen@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Tejun Heo <tj@kernel.org>
Cc: Yosry Ahmed <yosry.ahmed@linux.dev>
Cc: Christian Brauner <brauner@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Setting the max and high limits can trigger synchronous reclaim and/or
oom-kill if the usage is higher than the given limit. This behavior is
fine for newly created cgroups but it can cause issues for the node
controller while setting limits for existing cgroups.
In our production multi-tenant and overcommitted environment, we are
seeing priority inversion when the node controller dynamically adjusts the
limits of running jobs of different priorities. Based on the system
situation, the node controller may reduce the limits of lower priority
jobs and increase the limits of higher priority jobs. However we are
seeing node controller getting stuck for long period of time while
reclaiming from lower priority jobs while setting their limits and also
spends a lot of its own CPU.
One of the workaround we are trying is to fork a new process which sets
the limit of the lower priority job along with setting an alarm to get
itself killed if it get stuck in the reclaim for lower priority job.
However we are finding it very unreliable and costly. Either we need a
good enough time buffer for the alarm to be delivered after setting limit
and potentialy spend a lot of CPU in the reclaim or be unreliable in
setting the limit for much shorter but cheaper (less reclaim) alarms.
Let's introduce new limit setting option which does not trigger reclaim
and/or oom-kill and let the processes in the target cgroup to trigger
reclaim and/or throttling and/or oom-kill in their next charge request.
This will make the node controller on multi-tenant overcommitted
environment much more reliable.
Explanation from Johannes on side-effects of O_NONBLOCK limit change:
It's usually the allocating tasks inside the group bearing the cost of
limit enforcement and reclaim. This allows a (privileged) updater from
outside the group to keep that cost in there - instead of having to
help, from a context that doesn't necessarily make sense.
I suppose the tradeoff with that - and the reason why this was doing
sync reclaim in the first place - is that, if the group is idle and
not trying to allocate more, it can take indefinitely for the new
limit to actually be met.
It should be okay in most scenarios in practice. As the capacity is
reallocated from group A to B, B will exert pressure on A once it
tries to claim it and thereby shrink it down. If A is idle, that
shouldn't be hard. If A is running, it's likely to fault/allocate
soon-ish and then join the effort.
It does leave a (malicious) corner case where A is just busy-hitting
its memory to interfere with the clawback. This is comparable to
reclaiming memory.low overage from the outside, though, which is an
acceptable risk. Users of O_NONBLOCK just need to be aware.
Link: https://lkml.kernel.org/r/20250419183545.1982187-1-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Yosry Ahmed <yosry.ahmed@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Use cl@gentwo.org throughout and remove the old email addresses.
Link: https://lkml.kernel.org/r/8b962f57-4d98-cbb0-cd82-b6ba456733e8@gentwo.org
Signed-off-by: Christoph Lameter <cl@gentwo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Add description of 'nid' file, which is optionally used for specific DAMOS
quota goal metrics such as node_mem_{used,free}_bp on DAMON usage
document.
Link: https://lkml.kernel.org/r/20250420194030.75838-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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On Intel TDX guest, unaccepted memory is unusable free memory which is not
managed by buddy, until it's accepted by guest. Before that, it cannot be
accessed by the first kernel as well as the kexec'ed kernel. The kexec'ed
kernel will skip these pages and fill in zero data for the reader of
vmcore.
The dump tool like makedumpfile creates a page descriptor (size 24 bytes)
for each non-free page, including zero data page, but it will not create
descriptor for free pages. If it is not able to distinguish these
unaccepted pages with zero data pages, a certain amount of space will be
wasted in proportion (~1/170). In fact, as a special kind of free page
the unaccepted pages should be excluded, like the real free pages.
Export the page type PAGE_UNACCEPTED_MAPCOUNT_VALUE to vmcoreinfo, so that
dump tool can identify whether a page is unaccepted.
[zhiquan1.li@intel.com: fix docs: "Title underline too short" warning]
Link: https://lore.kernel.org/all/20240809114854.3745464-5-kirill.shutemov@linux.intel.com/
Link: https://lkml.kernel.org/r/20250405060610.860465-1-zhiquan1.li@intel.com
Link: https://lore.kernel.org/all/20240809114854.3745464-5-kirill.shutemov@linux.intel.com/
Link: https://lkml.kernel.org/r/20250403030801.758687-1-zhiquan1.li@intel.com
Signed-off-by: Zhiquan Li <zhiquan1.li@intel.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Zhiquan Li <zhiquan1.li@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Move IDLE pages tracking into a separate chapter because there are
multiple features that use (or depend on) it either in built-in variant
("mark all") or in extended variant (ac-time tracking).
In addition, recompression doesn't require memory tracking to be enabled
in order to be able to perform idle recompression.
Link: https://lkml.kernel.org/r/20250416042833.3858827-1-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reported-by: Shin Kawamura <kawasin@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "fs/proc: extend the PAGEMAP_SCAN ioctl to report guard
regions", v2.
Introduce the PAGE_IS_GUARD flag in the PAGEMAP_SCAN ioctl to expose
information about guard regions. This allows userspace tools, such as
CRIU, to detect and handle guard regions.
Currently, CRIU utilizes PAGEMAP_SCAN as a more efficient alternative to
parsing /proc/pid/pagemap. Without this change, guard regions are
incorrectly reported as swap-anon regions, leading CRIU to attempt dumping
them and subsequently failing.
The series includes updates to the documentation and selftests to reflect
the new functionality.
This patch (of 3):
Introduce the PAGE_IS_GUARD flag in the PAGEMAP_SCAN ioctl to expose
information about guard regions. This allows userspace tools, such as
CRIU, to detect and handle guard regions.
Link: https://lkml.kernel.org/r/20250324065328.107678-1-avagin@google.com
Link: https://lkml.kernel.org/r/20250324065328.107678-2-avagin@google.com
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Reduce the diff between low and high watermarks when compaction
proactiveness is set to high. This allows users who set the proactiveness
really high to have more stable fragmentation score over time.
Link: https://lkml.kernel.org/r/20250404111103.1994507-3-mclapinski@google.com
Signed-off-by: Michal Clapinski <mclapinski@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The writeback interface supports a page_index=N parameter which performs
writeback of the given page. Since we rarely need to writeback just one
single page, the typical use case involves a number of writeback calls,
each performing writeback of one page:
echo page_index=100 > zram0/writeback
...
echo page_index=200 > zram0/writeback
echo page_index=500 > zram0/writeback
...
echo page_index=700 > zram0/writeback
One obvious downside of this is that it increases the number of syscalls.
Less obvious, but a significantly more important downside, is that when
given only one page to post-process zram cannot perform an optimal target
selection. This becomes a critical limitation when writeback_limit is
enabled, because under writeback_limit we want to guarantee the highest
memory savings hence we first need to writeback pages that release the
highest amount of zsmalloc pool memory.
This patch adds page_indexes=LOW-HIGH parameter to the writeback
interface:
echo page_indexes=100-200 page_indexes=500-700 > zram0/writeback
This gives zram a chance to apply an optimal target selection strategy on
each iteration of the writeback loop.
We also now permit multiple page_index parameters per call (previously
zram would recognize only one page_index) and a mix or single pages and
page ranges:
echo page_index=42 page_index=99 page_indexes=100-200 \
page_indexes=500-700 > zram0/writeback
Apart from that the patch also unifies parameters passing and resembles
other "modern" zram device attributes (e.g. recompression), while the old
interface used a mixed scheme: values-less parameters for mode and a
key=value format for page_index. We still support the "old" value-less
format for compatibility reasons.
[senozhatsky@chromium.org: simplify parse_page_index() range checks, per Brian]
nk: https://lkml.kernel.org/r/20250404015327.2427684-1-senozhatsky@chromium.org
[sozhatsky@chromium.org: fix uninitialized variable in zram_writeback_slots(), per Dan]
nk: https://lkml.kernel.org/r/20250409112611.1154282-1-senozhatsky@chromium.org
Link: https://lkml.kernel.org/r/20250327015818.4148660-1-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Brian Geffon <bgeffon@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Richard Chang <richardycc@google.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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When retpoline mitigation is enabled for spectre-v2, enabling
call-depth-tracking and RSB stuffing also mitigates ITS. Add cmdline option
indirect_target_selection=stuff to allow enabling RSB stuffing mitigation.
When retpoline mitigation is not enabled, =stuff option is ignored, and
default mitigation for ITS is deployed.
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
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Ice Lake generation CPUs are not affected by guest/host isolation part of
ITS. If a user is only concerned about KVM guests, they can now choose a
new cmdline option "vmexit" that will not deploy the ITS mitigation when
CPU is not affected by guest/host isolation. This saves the performance
overhead of ITS mitigation on Ice Lake gen CPUs.
When "vmexit" option selected, if the CPU is affected by ITS guest/host
isolation, the default ITS mitigation is deployed.
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
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Indirect Target Selection (ITS) is a bug in some pre-ADL Intel CPUs with
eIBRS. It affects prediction of indirect branch and RETs in the
lower half of cacheline. Due to ITS such branches may get wrongly predicted
to a target of (direct or indirect) branch that is located in the upper
half of the cacheline.
Scope of impact
===============
Guest/host isolation
--------------------
When eIBRS is used for guest/host isolation, the indirect branches in the
VMM may still be predicted with targets corresponding to branches in the
guest.
Intra-mode
----------
cBPF or other native gadgets can be used for intra-mode training and
disclosure using ITS.
User/kernel isolation
---------------------
When eIBRS is enabled user/kernel isolation is not impacted.
Indirect Branch Prediction Barrier (IBPB)
-----------------------------------------
After an IBPB, indirect branches may be predicted with targets
corresponding to direct branches which were executed prior to IBPB. This is
mitigated by a microcode update.
Add cmdline parameter indirect_target_selection=off|on|force to control the
mitigation to relocate the affected branches to an ITS-safe thunk i.e.
located in the upper half of cacheline. Also add the sysfs reporting.
When retpoline mitigation is deployed, ITS safe-thunks are not needed,
because retpoline sequence is already ITS-safe. Similarly, when call depth
tracking (CDT) mitigation is deployed (retbleed=stuff), ITS safe return
thunk is not used, as CDT prevents RSB-underflow.
To not overcomplicate things, ITS mitigation is not supported with
spectre-v2 lfence;jmp mitigation. Moreover, it is less practical to deploy
lfence;jmp mitigation on ITS affected parts anyways.
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
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Add the admin-guide for Indirect Target Selection (ITS).
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
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Turn the default 5 second test delay for hibernation into a
configurable module parameter, so users can determine how
long to wait in this pseudo-hibernate state before resuming
the system.
The configurable delay parameter has been added for suspend, so
add an analogous one for hibernation.
Example (wait 30 seconds);
# echo 30 > /sys/module/hibernate/parameters/pm_test_delay
# echo core > /sys/power/pm_test
Signed-off-by: Zihuan Zhang <zhangzihuan@kylinos.cn>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://patch.msgid.link/20250507063520.419635-1-zhangzihuan@kylinos.cn
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Add the file 'c3-isp.rst' that documents the c3-isp driver.
Signed-off-by: Keke Li <keke.li@amlogic.com>
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
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Introduce a mount option to allow sysadmins to specify the maximum size
of an atomic write. If the filesystem can work with the supplied value,
that becomes the new guaranteed maximum.
The value mustn't be too big for the existing filesystem geometry (max
write size, max AG/rtgroup size). We dynamically recompute the
tr_atomic_write transaction reservation based on the given block size,
check that the current log size isn't less than the new minimum log size
constraints, and set a new maximum.
The actual software atomic write max is still computed based off of
tr_atomic_ioend the same way it has for the past few commits. Note also
that xfs_calc_atomic_write_log_geometry is non-static because mkfs will
need that.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: John Garry <john.g.garry@oracle.com>
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Sphinx reports missing toctree entry warning:
Documentation/admin-guide/hw-vuln/old_microcode.rst: WARNING: document isn't included in any toctree
Add entry for "Old Microcode" docs to fix the warning.
Fixes: 4e2c719782a847 ("x86/cpu: Help users notice when running old Intel microcode")
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/all/20250502023358.14846-1-bagasdotme%40gmail.com
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Introduce the zoned_loop.rst documentation file under
admin-guide/blockdev to document the zoned loop block device driver.
An overview of the driver is provided and its usage to create and delete
zoned devices described.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250407075222.170336-3-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Cross-merge networking fixes after downstream PR (net-6.15-rc5).
No conflicts or adjacent changes.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Commit a3e8fe814ad1 ("x86/build: Raise the minimum GCC version to 8.1")
raised the minimum compiler version as enforced by Kbuild to gcc-8.1
and clang-15 for x86.
This is actually the same gcc version that has been discussed as the
minimum for all architectures several times in the past, with little
objection. A previous concern was the kernel for SLE15-SP7 needing to
be built with gcc-7. As this ended up still using linux-6.4 and there
is no plan for an SP8, this is no longer a problem.
Change it for all architectures and adjust the documentation accordingly.
A few version checks can be removed in the process. The binutils
version 2.30 is the lowest version used in combination with gcc-8 on
common distros, so use that as the corresponding minimum.
Link: https://lore.kernel.org/lkml/20240925150059.3955569-32-ardb+git@google.com/
Link: https://lore.kernel.org/lkml/871q7yxrgv.wl-tiwai@suse.de/
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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Fix the document title and reword the phrasing to active voice.
Signed-off-by: Joel Savitz <jsavitz@redhat.com>
Message-ID: <20250421161723.1138903-1-jsavitz@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Add some basic info about the HW/driver + contact info.
Signed-off-by: Martin Tůma <martin.tuma@digiteqautomotive.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
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With commit dcbb01fbb7ae ("x86/pci: Remove old STA2x11 support"), the
STA2X11 Video Input Port driver is not needed and cannot be built anymore.
Remove the driver and its reference in media documentation.
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@redhat.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
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Add documentation about the Thunderbolt/USB4 tunneling events to the
user’s and administrator’s guide.
Signed-off-by: Alan Borzeszkowski <alan.borzeszkowski@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
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Remove the duplicated section and while at it, turn spaces into tabs.
Signed-off-by: Hans Holmberg <hans.holmberg@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Fixes: c7b67ddc3c99 ("xfs: document zoned rt specifics in admin-guide")
Signed-off-by: Carlos Maiolino <cem@kernel.org>
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Old microcode is bad for users and for kernel developers.
For users, it exposes them to known fixed security and/or functional
issues. These obviously rarely result in instant dumpster fires in
every environment. But it is as important to keep your microcode up
to date as it is to keep your kernel up to date.
Old microcode also makes kernels harder to debug. A developer looking
at an oops need to consider kernel bugs, known CPU issues and unknown
CPU issues as possible causes. If they know the microcode is up to
date, they can mostly eliminate known CPU issues as the cause.
Make it easier to tell if CPU microcode is out of date. Add a list
of released microcode. If the loaded microcode is older than the
release, tell users in a place that folks can find it:
/sys/devices/system/cpu/vulnerabilities/old_microcode
Tell kernel kernel developers about it with the existing taint
flag:
TAINT_CPU_OUT_OF_SPEC
== Discussion ==
When a user reports a potential kernel issue, it is very common
to ask them to reproduce the issue on mainline. Running mainline,
they will (independently from the distro) acquire a more up-to-date
microcode version list. If their microcode is old, they will
get a warning about the taint and kernel developers can take that
into consideration when debugging.
Just like any other entry in "vulnerabilities/", users are free to
make their own assessment of their exposure.
== Microcode Revision Discussion ==
The microcode versions in the table were generated from the Intel
microcode git repo:
8ac9378a8487 ("microcode-20241112 Release")
which as of this writing lags behind the latest microcode-20250211.
It can be argued that the versions that the kernel picks to call "old"
should be a revision or two old. Which specific version is picked is
less important to me than picking *a* version and enforcing it.
This repository contains only microcode versions that Intel has deemed
to be OS-loadable. It is quite possible that the BIOS has loaded a
newer microcode than the latest in this repo. If this happens, the
system is considered to have new microcode, not old.
Specifically, the sysfs file and taint flag answer the question:
Is the CPU running on the latest OS-loadable microcode,
or something even later that the BIOS loaded?
In other words, Intel never publishes an authoritative list of CPUs
and latest microcode revisions. Until it does, this is the best that
Linux can do.
Also note that the "intel-ucode-defs.h" file is simple, ugly and
has lots of magic numbers. That's on purpose and should allow a
single file to be shared across lots of stable kernel regardless of if
they have the new "VFM" infrastructure or not. It was generated with
a dumb script.
== FAQ ==
Q: Does this tell me if my system is secure or insecure?
A: No. It only tells you if your microcode was old when the
system booted.
Q: Should the kernel warn if the microcode list itself is too old?
A: No. New kernels will get new microcode lists, both mainline
and stable. The only way to have an old list is to be running
an old kernel in which case you have bigger problems.
Q: Is this for security or functional issues?
A: Both.
Q: If a given microcode update only has functional problems but
no security issues, will it be considered old?
A: Yes. All microcode image versions within a microcode release
are treated identically. Intel appears to make security
updates without disclosing them in the release notes. Thus,
all updates are considered to be security-relevant.
Q: Who runs old microcode?
A: Anybody with an old distro. This happens all the time inside
of Intel where there are lots of weird systems in labs that
might not be getting regular distro updates and might also
be running rather exotic microcode images.
Q: If I update my microcode after booting will it stop saying
"Vulnerable"?
A: No. Just like all the other vulnerabilies, you need to
reboot before the kernel will reassess your vulnerability.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: "Ahmed S. Darwish" <darwi@linutronix.de>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/all/20250421195659.CF426C07%40davehans-spike.ostc.intel.com
(cherry picked from commit 9127865b15eb0a1bd05ad7efe29489c44394bdc1)
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Cross-merge networking fixes after downstream PR (net-6.15-rc3).
No conflicts. Adjacent changes:
tools/net/ynl/pyynl/ynl_gen_c.py
4d07bbf2d456 ("tools: ynl-gen: don't declare loop iterator in place")
7e8ba0c7de2b ("tools: ynl: don't use genlmsghdr in classic netlink")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Document the lifetime, nolifetime and max_open_zones mount options
added for zoned rt file systems.
Also add documentation describing the max_open_zones sysfs attribute
exposed in /sys/fs/xfs/<dev>/zoned/
Fixes: 4e4d52075577 ("xfs: add the zoned space allocator")
Signed-off-by: Hans Holmberg <hans.holmberg@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
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Document the intel_idle driver sysfs file for enabling/disabling C1
demotion.
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Link: https://patch.msgid.link/20250317135541.1471754-3-dedekind1@gmail.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Change a few words and abbreviations/punctuation.
Change one echo command to include a trailing '`'.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linux-pm@vger.kernel.org
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20250405001447.4039463-1-rdunlap@infradead.org
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According to the reStructuredText documentation, internal hyperlink
targets[1] are intended to resolve within the current document.
Sphinx has a bug that causes internal hyperlinks declared with
duplicate names to resolve nondeterministically, producing incorrect
documentation. Sphinx does not yet emit a warning when these
duplicate target names are declared.
To improve the reproducibility and correctness of the HTML
documentation, disambiguate two labels both previously titled
"submit_improvements".
[1] - https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html#hyperlink-targets
Link: https://github.com/sphinx-doc/sphinx/issues/13383
Signed-off-by: James Addison <jay@jp-hosting.net>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20250407195120.331103-2-jvanderwaa@redhat.com
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Presently we start garbage collection late - when we start running
out of free zones to backfill max_open_zones. This is a reasonable
default as it minimizes write amplification. The longer we wait,
the more blocks are invalidated and reclaim cost less in terms
of blocks to relocate.
Starting this late however introduces a risk of GC being outcompeted
by user writes. If GC can't keep up, user writes will be forced to
wait for free zones with high tail latencies as a result.
This is not a problem under normal circumstances, but if fragmentation
is bad and user write pressure is high (multiple full-throttle
writers) we will "bottom out" of free zones.
To mitigate this, introduce a zonegc_low_space tunable that lets the
user specify a percentage of how much of the unused space that GC
should keep available for writing. A high value will reclaim more of
the space occupied by unused blocks, creating a larger buffer against
write bursts.
This comes at a cost as write amplification is increased. To
illustrate this using a sample workload, setting zonegc_low_space to
60% avoids high (500ms) max latencies while increasing write
amplification by 15%.
Signed-off-by: Hans Holmberg <hans.holmberg@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
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DCCP was orphaned in 2021 by commit 054c4610bd05 ("MAINTAINERS: dccp:
move Gerrit Renker to CREDITS"), which noted that the last maintainer
had been inactive for five years.
In recent years, it has become a playground for syzbot, and most changes
to DCCP have been odd bug fixes triggered by syzbot. Apart from that,
the only changes have been driven by treewide or networking API updates
or adjustments related to TCP.
Thus, in 2023, we announced we would remove DCCP in 2025 via commit
b144fcaf46d4 ("dccp: Print deprecation notice.").
Since then, only one individual has contacted the netdev mailing list. [0]
There is ongoing research for Multipath DCCP. The repository is hosted
on GitHub [1], and development is not taking place through the upstream
community. While the repository is published under the GPLv2 license,
the scheduling part remains proprietary, with a LICENSE file [2] stating:
"This is not Open Source software."
The researcher mentioned a plan to address the licensing issue, upstream
the patches, and step up as a maintainer, but there has been no further
communication since then.
Maintaining DCCP for a decade without any real users has become a burden.
Therefore, it's time to remove it.
Removing DCCP will also provide significant benefits to TCP. It allows
us to freely reorganize the layout of struct inet_connection_sock, which
is currently shared with DCCP, and optimize it to reduce the number of
cachelines accessed in the TCP fast path.
Note that we keep DCCP netfilter modules as requested. [3]
Link: https://lore.kernel.org/netdev/20230710182253.81446-1-kuniyu@amazon.com/T/#u #[0]
Link: https://github.com/telekom/mp-dccp #[1]
Link: https://github.com/telekom/mp-dccp/blob/mpdccp_v03_k5.10/net/dccp/non_gpl_scheduler/LICENSE #[2]
Link: https://lore.kernel.org/netdev/Z_VQ0KlCRkqYWXa-@calendula/ #[3]
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Paul Moore <paul@paul-moore.com> (LSM and SELinux)
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Link: https://patch.msgid.link/20250410023921.11307-3-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Add driver admin-guide documentation for the alienware-wmi driver.
Reviewed-by: Armin Wolf <W_Armin@gmx.de>
Signed-off-by: Kurt Borja <kuurtb@gmail.com>
Link: https://lore.kernel.org/r/20250329-hwm-v7-11-a14ea39d8a94@gmail.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
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Add documentation for the newly added configfs-based interface for GPIO
aggregator.
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Link: https://lore.kernel.org/r/20250407043019.4105613-9-koichiro.den@canonical.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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Create a document to summarize hard-earned knowledge about RSB-related
mitigations, with references, and replace the overly verbose yet
incomplete comments with a reference to the document.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/ab73f4659ba697a974759f07befd41ae605e33dd.1744148254.git.jpoimboe@kernel.org
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First of all, using 'mmio' prevents proper implementation of 8-bit accessors.
Second, it's simply inconsistent with uart8250 set of options. Rename it to
'mmio32'. While at it, remove rather misleading comment in the documentation.
From now on mmio32 is self-explanatory and pciserial supports not only 32-bit
MMIO accessors.
Also, while at it, fix the comment for the "pciserial" case. The comment
seems to be a copy'n'paste error when mentioning "serial" instead of
"pciserial" (with double quotes). Fix this.
With that, move it upper, so we don't calculate 'buf' twice.
Fixes: 3181424aeac2 ("x86/early_printk: Add support for MMIO-based UARTs")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Denis Mukhin <dmukhin@ford.com>
Link: https://lore.kernel.org/r/20250407172214.792745-1-andriy.shevchenko@linux.intel.com
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Only simple implementation with a static key wrapper, it will be wired
in later.
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250310170442.504716-5-mkoutny@suse.com
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All callers and implementations are now removed, so remove the operation
and update the documentation to match.
Signed-off-by: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Link: https://lore.kernel.org/r/20250402150005.2309458-10-willy@infradead.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull more s390 updates from Vasily Gorbik:
- Fix machine check handler _CIF_MCCK_GUEST bit setting by adding the
missing base register for relocated lowcore address
- Fix build failure on older linkers by conditionally adding the
-no-pie linker option only when it is supported
- Fix inaccurate kernel messages in vfio-ap by providing descriptive
error notifications for AP queue sharing violations
- Fix PCI isolation logic by ensuring non-VF devices correctly return
false in zpci_bus_is_isolated_vf()
- Fix PCI DMA range map setup by using dma_direct_set_offset() to add a
proper sentinel element, preventing potential overruns and
translation errors
- Cleanup header dependency problems with asm-offsets.c
- Add fault info for unexpected low-address protection faults in user
mode
- Add support for HOTPLUG_SMT, replacing the arch-specific "nosmt"
handling with common code handling
- Use bitop functions to implement CPU flag helper functions to ensure
that bits cannot get lost if modified in different contexts on a CPU
- Remove unused machine_flags for the lowcore
* tag 's390-6.15-2' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
s390/vfio-ap: Fix no AP queue sharing allowed message written to kernel log
s390/pci: Fix dev.dma_range_map missing sentinel element
s390/mm: Dump fault info in case of low address protection fault
s390/smp: Add support for HOTPLUG_SMT
s390: Fix linker error when -no-pie option is unavailable
s390/processor: Use bitop functions for cpu flag helper functions
s390/asm-offsets: Remove ASM_OFFSETS_C
s390/asm-offsets: Include ftrace_regs.h instead of ftrace.h
s390/kvm: Split kvm_host header file
s390/pci: Fix zpci_bus_is_isolated_vf() for non-VFs
s390/lowcore: Remove unused machine_flags
s390/entry: Fix setting _CIF_MCCK_GUEST with lowcore relocation
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git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
Pull RISC-V updates from Palmer Dabbelt:
- The sub-architecture selection Kconfig system has been cleaned up,
the documentation has been improved, and various detections have been
fixed
- The vector-related extensions dependencies are now validated when
parsing from device tree and in the DT bindings
- Misaligned access probing can be overridden via a kernel command-line
parameter, along with various fixes to misalign access handling
- Support for relocatable !MMU kernels builds
- Support for hpge pfnmaps, which should improve TLB utilization
- Support for runtime constants, which improves the d_hash()
performance
- Support for bfloat16, Zicbom, Zaamo, Zalrsc, Zicntr, Zihpm
- Various fixes, including:
- We were missing a secondary mmu notifier call when flushing the
tlb which is required for IOMMU
- Fix ftrace panics by saving the registers as expected by ftrace
- Fix a couple of stimecmp usage related to cpu hotplug
- purgatory_start is now aligned as per the STVEC requirements
- A fix for hugetlb when calculating the size of non-present PTEs
* tag 'riscv-for-linus-6.15-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (65 commits)
riscv: Add norvc after .option arch in runtime const
riscv: Make sure toolchain supports zba before using zba instructions
riscv/purgatory: 4B align purgatory_start
riscv/kexec_file: Handle R_RISCV_64 in purgatory relocator
selftests: riscv: fix v_exec_initval_nolibc.c
riscv: Fix hugetlb retrieval of number of ptes in case of !present pte
riscv: print hartid on bringup
riscv: Add norvc after .option arch in runtime const
riscv: Remove CONFIG_PAGE_OFFSET
riscv: Support CONFIG_RELOCATABLE on riscv32
asm-generic: Always define Elf_Rel and Elf_Rela
riscv: Support CONFIG_RELOCATABLE on NOMMU
riscv: Allow NOMMU kernels to access all of RAM
riscv: Remove duplicate CONFIG_PAGE_OFFSET definition
RISC-V: errata: Use medany for relocatable builds
dt-bindings: riscv: document vector crypto requirements
dt-bindings: riscv: add vector sub-extension dependencies
dt-bindings: riscv: d requires f
RISC-V: add f & d extension validation checks
RISC-V: add vector crypto extension validation checks
...
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