JIRA: https://issues.redhat.com/browse/RHEL-83455
Conflicts: A merge conflict in lib/Makefile and context diff in MAINTAINERS.
commit 93c8332c8373fee415bd79f08d5ba4ba7ca5ad15
Author: Xavier <xavier_qy@163.com>
Date: Thu, 4 Jul 2024 14:24:43 +0800
Union-Find: add a new module in kernel library
This patch implements a union-find data structure in the kernel library,
which includes operations for allocating nodes, freeing nodes,
finding the root of a node, and merging two nodes.
Signed-off-by: Xavier <xavier_qy@163.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Waiman Long <longman@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-58641
Upstream Status: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Conflicts: In Documentation/ABI/testing/sysfs-devices-system-cpu, there
is conflict because of context fuzz.
commit c91c6062d6cd1bc366efb04973ee449c30398a49
Author: Sourabh Jain <sourabhjain@linux.ibm.com>
Date: Mon Aug 12 09:46:51 2024 +0530
Document/kexec: generalize crash hotplug description
Commit 79365026f869 ("crash: add a new kexec flag for hotplug support")
generalizes the crash hotplug support to allow architectures to update
multiple kexec segments on CPU/Memory hotplug and not just elfcorehdr.
Therefore, update the relevant kernel documentation to reflect the same.
No functional change.
Link: https://lkml.kernel.org/r/20240812041651.703156-1-sourabhjain@linux.ibm.com
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Reviewed-by: Petr Tesarik <ptesarik@suse.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Petr Tesarik <petr@tesarici.cz>
Cc: Sourabh Jain <sourabhjain@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Baoquan He <bhe@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-27745
This patch is a backport of the following upstream commit:
commit 9bc1d3cdb904170214456bca96c4924f28522ab8
Author: Peng Zhang <zhangpeng.00@bytedance.com>
Date: Fri Oct 27 11:38:41 2023 +0800
maple_tree: update the documentation of maple tree
Introduce the new interface mtree_dup() in the documentation.
Link: https://lkml.kernel.org/r/20231027033845.90608-7-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Mike Christie <michael.christie@oracle.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Rafael Aquini <raquini@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-55461
This patch is a backport of the following upstream commit:
commit f8c1d4ca55177326adad1fdc6bf602423a507542
Author: Ira Weiny <ira.weiny@intel.com>
Date: Tue Apr 19 10:06:06 2022 -0700
Documentation/protection-keys: Clean up documentation for User Space pkeys
The documentation for user space pkeys was a bit dated including things
such as Amazon and distribution testing information which is irrelevant
now.
Update the documentation. This also streamlines adding the Supervisor
pkey documentation later on.
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/20220419170649.1022246-2-ira.weiny@intel.com
Signed-off-by: Audra Mitchell <audra@redhat.com>
MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/5252
JIRA: https://issues.redhat.com/browse/RHEL-27743
JIRA: https://issues.redhat.com/browse/RHEL-59459
CVE: CVE-2024-46787
Depends: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/4961
This MR brings RHEL9 core MM code up to upstream's v6.6 LTS level.
This work follows up on the previous v6.5 update (RHEL-27742) and as such,
the bulk of this changeset is comprised of refactoring and clean-ups of
the internal implementation of several APIs as it further advances the
conversion to FOLIOS, and follow up on the per-VMA locking changes.
Also, with the rebase to v6.6 LTS, we complete the infrastructure to allow
Control-flow Enforcement Technology, a.k.a. Shadow Stacks, for x86 builds,
and we add a potential extra level of protection (assessment pending) to help
on mitigating kernel heap exploits dubbed as "SlubStick".
Follow-up fixes are omitted from this series either because they are irrelevant to
the bits we support on RHEL or because they depend on bigger changesets introduced
upstream more recently. A follow-up ticket (RHEL-27745) will deal with these and other cases separately.
Omitted-fix: e540b8c5da04 ("mips: mm: add slab availability checking in ioremap_prot")
Omitted-fix: f7875966dc0c ("tools headers UAPI: Sync files changed by new fchmodat2 and map_shadow_stack syscalls with the kernel sources")
Omitted-fix: df39038cd895 ("s390/mm: Fix VM_FAULT_HWPOISON handling in do_exception()")
Omitted-fix: 12bbaae7635a ("mm: create FOLIO_FLAG_FALSE and FOLIO_TYPE_OPS macros")
Omitted-fix: fd1a745ce03e ("mm: support page_mapcount() on page_has_type() pages")
Omitted-fix: d99e3140a4d3 ("mm: turn folio_test_hugetlb into a PageType")
Omitted-fix: fa2690af573d ("mm: page_ref: remove folio_try_get_rcu()")
Omitted-fix: f442fa614137 ("mm: gup: stop abusing try_grab_folio")
Omitted-fix: cb0f01beb166 ("mm/mprotect: fix dax pud handling")
Signed-off-by: Rafael Aquini <raquini@redhat.com>
Approved-by: John W. Linville <linville@redhat.com>
Approved-by: Mark Salter <msalter@redhat.com>
Approved-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Approved-by: Chris von Recklinghausen <crecklin@redhat.com>
Approved-by: Steve Best <sbest@redhat.com>
Approved-by: David Airlie <airlied@redhat.com>
Approved-by: Michal Schmidt <mschmidt@redhat.com>
Approved-by: Baoquan He <5820488-baoquan_he@users.noreply.gitlab.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>
Merged-by: Rado Vrbovsky <rvrbovsk@redhat.com>
MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/5113
# Merge Request Required Information
JIRA: https://issues.redhat.com/browse/RHEL-36247
JIRA: https://issues.redhat.com/browse/RHEL-54186
JIRA: https://issues.redhat.com/browse/RHEL-54189
JIRA: https://issues.redhat.com/browse/RHEL-55199
JIRA: https://issues.redhat.com/browse/RHEL-55200
JIRA: https://issues.redhat.com/browse/RHEL-55448
JIRA: https://issues.redhat.com/browse/RHEL-55450
JIRA: https://issues.redhat.com/browse/RHEL-55466
JIRA: https://issues.redhat.com/browse/RHEL-57229
Upstream: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
CVE: CVE-2024-44994
## Summary of Changes
This brings the IOMMU and DMA api subsystems in line with v6.11. Overall it is smaller than normal, but I expect there will be another MR later on with some things landing in v6.12. In addition to the usual fixes, and cleanups the major changes are:
- iommufd io page fault support
- smmuv3 dirty page tracking support
- vt-d cache tagging support
- iommu memory usage observability support
- Some cleanups from Robin related to dma range calculation, arch setup_dma_ops, and iommu_fwspec_ops
- Another batch of updates to smmuv3 from Jason's reworking of the driver (2b/3)
There also is a rhel only cleanup to deal with a cleanup in the iommufd code by Linus in one of merges that was related to some mm changes at the time, but wasn't dealt with when the iommufd or mm changes were merged to rhel.
Testing:
- kernel-tests iommu new-boot testing
- kernel-tests iommu fio testing
- kernel-tests dmatest and idxd tests
- iommufd kernel selftest
- general cki testing
v5: Added 3 fixes that recently landed upstream.
v6: Resolve issues raised by Don:
- Conflicts note updates
- Backport of acpi, and arm7 io-pgtable commit.
- While doing this I went through to diff against upstream and cleaned up a couple more merge commit cleanups:
* __GFP_ZERO use in amd ppr log alloc code.
* Line break in swiotlb code.
* dead config option in drivers/iommu/intel/Kconfig
- Hyperv commit that was missed in previous backports.
v7: Fixed typo from using Conflict instead of Conflicts for tag.
v8: Fixed borked conflict resolution after adding acpi patch in v6.
v10: Added dt bindings commit mentioned by Eric.
v11: Rebase due to merge conflict after acpi MR merged. This also drops a couple acpi commits that were now empty.
Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>
## Approved Development Ticket
All submissions to CentOS Stream must reference an approved ticket in [Red Hat Jira](https://issues.redhat.com/). Please follow the CentOS Stream [contribution documentation](https://docs.centos.org/en-US/stream-contrib/quickstart/) for how to file this ticket and have it approved.
Approved-by: José Ignacio Tornos Martínez <jtornosm@redhat.com>
Approved-by: Mark Salter <msalter@redhat.com>
Approved-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Approved-by: Donald Dutile <ddutile@redhat.com>
Approved-by: Steve Best <sbest@redhat.com>
Approved-by: David Arcari <darcari@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>
Merged-by: Rado Vrbovsky <rvrbovsk@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-27743
This patch is a backport of the following upstream commit:
commit 61ff748b5b7b0c32daddbfb92c3bc15d938754dc
Author: Matthew Wilcox (Oracle) <willy@infradead.org>
Date: Fri Aug 18 21:06:30 2023 +0100
mm: add orphaned kernel-doc to the rst files.
There are many files in mm/ that contain kernel-doc which is not
currently published on kernel.org. Some of it is easily categorisable,
but most of it is going into the miscellaneous documentation section to
be organised later.
Some files aren't ready to be included; they contain documentation with
build errors. Or they're nommu.c which duplicates documentation from
"real" MMU systems. Those files are noted with a # mark (although really
anything which isn't a recognised directive would do to prevent inclusion)
Link: https://lkml.kernel.org/r/20230818200630.2719595-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Rafael Aquini <raquini@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-27743
This patch is a backport of the following upstream commit:
commit 29d26f1215de14721188988a59b1426abb85b7be
Author: Matthew Wilcox (Oracle) <willy@infradead.org>
Date: Wed Aug 2 16:13:33 2023 +0100
mm: remove ARCH_IMPLEMENTS_FLUSH_DCACHE_FOLIO
Current best practice is to reuse the name of the function as a define to
indicate that the function is implemented by the architecture.
Link: https://lkml.kernel.org/r/20230802151406.3735276-6-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Rafael Aquini <raquini@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-27743
This patch is a backport of the following upstream commit:
commit 3a255267f6dff40e193501cf731f409ce9175503
Author: Matthew Wilcox (Oracle) <willy@infradead.org>
Date: Wed Aug 2 16:13:31 2023 +0100
mm: add generic flush_icache_pages() and documentation
flush_icache_page() is deprecated but not yet removed, so add a range
version of it. Change the documentation to refer to
update_mmu_cache_range() instead of update_mmu_cache().
Link: https://lkml.kernel.org/r/20230802151406.3735276-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Rafael Aquini <raquini@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-55466
Upstream Status: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
commit 82d71b53d7e732ede6028591342bdc80fabfa29f
Author: Lukas Bulwahn <lukas.bulwahn@redhat.com>
Date: Mon May 27 15:13:14 2024 +0200
Documentation/core-api: correct reference to SWIOTLB_DYNAMIC
Commit c93f261dfc39 ("Documentation/core-api: add swiotlb documentation")
accidentally refers to CONFIG_DYNAMIC_SWIOTLB in one place, while the
config is actually called CONFIG_SWIOTLB_DYNAMIC.
Correct the reference to the intended config option.
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@redhat.com>
Reviewed-by: Petr Tesarik <petr@tesarici.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
(cherry picked from commit 82d71b53d7e732ede6028591342bdc80fabfa29f)
Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-55466
Upstream Status: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
commit c93f261dfc395b1386320b2f0b160a6f34ed9ea5
Author: Michael Kelley <mhklinux@outlook.com>
Date: Wed May 1 08:16:51 2024 -0700
Documentation/core-api: add swiotlb documentation
There's currently no documentation for the swiotlb. Add documentation
describing usage scenarios, the key APIs, and implementation details.
Group the new documentation with other DMA-related documentation.
Signed-off-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Reviewed-by: Petr Tesarik <petr@tesarici.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
(cherry picked from commit c93f261dfc395b1386320b2f0b160a6f34ed9ea5)
Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-27742
This patch is a backport of the following upstream commit:
commit c8070b78751955e59b42457b974bea4a4fe00187
Author: David Howells <dhowells@redhat.com>
Date: Fri May 26 22:41:40 2023 +0100
mm: Don't pin ZERO_PAGE in pin_user_pages()
Make pin_user_pages*() leave a ZERO_PAGE unpinned if it extracts a pointer
to it from the page tables and make unpin_user_page*() correspondingly
ignore a ZERO_PAGE when unpinning. We don't want to risk overrunning a
zero page's refcount as we're only allowed ~2 million pins on it -
something that userspace can conceivably trigger.
Add a pair of functions to test whether a page or a folio is a ZERO_PAGE.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Christoph Hellwig <hch@infradead.org>
cc: David Hildenbrand <david@redhat.com>
cc: Lorenzo Stoakes <lstoakes@gmail.com>
cc: Andrew Morton <akpm@linux-foundation.org>
cc: Jens Axboe <axboe@kernel.dk>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: Matthew Wilcox <willy@infradead.org>
cc: Jan Kara <jack@suse.cz>
cc: Jeff Layton <jlayton@kernel.org>
cc: Jason Gunthorpe <jgg@nvidia.com>
cc: Logan Gunthorpe <logang@deltatee.com>
cc: Hillf Danton <hdanton@sina.com>
cc: Christian Brauner <brauner@kernel.org>
cc: Linus Torvalds <torvalds@linux-foundation.org>
cc: linux-fsdevel@vger.kernel.org
cc: linux-block@vger.kernel.org
cc: linux-kernel@vger.kernel.org
cc: linux-mm@kvack.org
Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20230526214142.958751-2-dhowells@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Rafael Aquini <raquini@redhat.com>
MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/4435
JIRA: https://issues.redhat.com/browse/RHEL-40250
Tested: Just built
Omitted-fix: 62776e4378ae9 ("mips: boot/compressed: use __NO_FORTIFY")
- No need to include this as MIPS arch is not supported in RHEL
Commits:
```
54d9469bc515 ("fortify: Add run-time WARN for cross-field memcpy()")
311fb40aa056 ("fortify: Use SIZE_MAX instead of (size_t)-1")
fa35198f3957 ("fortify: Explicitly check bounds are compile-time constants")
9f7d69c5cd23 ("fortify: Convert to struct vs member helpers")
03699f271de1 ("string: Rewrite and add more kern-doc for the str*() functions")
62e1cbfc5d79 ("fortify: Short-circuit known-safe calls to strscpy()")
439a1bcac648 ("fortify: Use __builtin_dynamic_object_size() when available")
26dd68d293fd ("overflow: add DEFINE_FLEX() for on-stack allocs")
21a2c74b0a2a ("fortify: Use const variables for __member_size tracking")
ead62aa370a8 ("fortify: strscpy: Fix flipped q and p docstring typo")
f0a6b5831cfb ("uml: Replace strlcpy with strscpy")
b229baa374db ("kernel.h: split out COUNT_ARGS() and CONCATENATE() to args.h")
e6584c3964f2 ("string: Allow 2-argument strscpy()")
f478898e0aa7 ("string: Redefine strscpy_pad() as a macro")
8366d124ec93 ("string: Allow 2-argument strscpy_pad()")
0d043351e5ba ("ext4: fix fortify warning in fs/ext4/fast_commit.c:1551")
b2ba00c2a517 ("rxrpc: replace zero-lenth array with DECLARE_FLEX_ARRAY() helper")
```
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Approved-by: Petr Oros <poros@redhat.com>
Approved-by: José Ignacio Tornos Martínez <jtornosm@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>
Merged-by: Lucas Zampieri <lzampier@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-28063
Conflicts:
Adding RHEL-only MODULE_STATS set to n for now. Possibly
add in future -debug kernels, to be determined.
Add rest of commit(s) to enable clean backport for further commits.
commit df3e764d8e5cd416efee29e0de3c93917dff5d33
Author: Luis Chamberlain <mcgrof@kernel.org>
Date: Tue Mar 28 20:03:19 2023 -0700
module: add debug stats to help identify memory pressure
Loading modules with finit_module() can end up using vmalloc(), vmap()
and vmalloc() again, for a total of up to 3 separate allocations in the
worst case for a single module. We always kernel_read*() the module,
that's a vmalloc(). Then vmap() is used for the module decompression,
and if so the last read buffer is freed as we use the now decompressed
module buffer to stuff data into our copy module. The last allocation is
specific to each architectures but pretty much that's generally a series
of vmalloc() calls or a variation of vmalloc to handle ELF sections with
special permissions.
Evaluation with new stress-ng module support [1] with just 100 ops
is proving that you can end up using GiBs of data easily even with all
care we have in the kernel and userspace today in trying to not load modules
which are already loaded. 100 ops seems to resemble the sort of pressure a
system with about 400 CPUs can create on module loading. Although issues
relating to duplicate module requests due to each CPU inucurring a new
module reuest is silly and some of these are being fixed, we currently lack
proper tooling to help diagnose easily what happened, when it happened
and who likely is to blame -- userspace or kernel module autoloading.
Provide an initial set of stats which use debugfs to let us easily scrape
post-boot information about failed loads. This sort of information can
be used on production worklaods to try to optimize *avoiding* redundant
memory pressure using finit_module().
There's a few examples that can be provided:
A 255 vCPU system without the next patch in this series applied:
Startup finished in 19.143s (kernel) + 7.078s (userspace) = 26.221s
graphical.target reached after 6.988s in userspace
And 13.58 GiB of virtual memory space lost due to failed module loading:
root@big ~ # cat /sys/kernel/debug/modules/stats
Mods ever loaded 67
Mods failed on kread 0
Mods failed on decompress 0
Mods failed on becoming 0
Mods failed on load 1411
Total module size 11464704
Total mod text size 4194304
Failed kread bytes 0
Failed decompress bytes 0
Failed becoming bytes 0
Failed kmod bytes 14588526272
Virtual mem wasted bytes 14588526272
Average mod size 171115
Average mod text size 62602
Average fail load bytes 10339140
Duplicate failed modules:
module-name How-many-times Reason
kvm_intel 249 Load
kvm 249 Load
irqbypass 8 Load
crct10dif_pclmul 128 Load
ghash_clmulni_intel 27 Load
sha512_ssse3 50 Load
sha512_generic 200 Load
aesni_intel 249 Load
crypto_simd 41 Load
cryptd 131 Load
evdev 2 Load
serio_raw 1 Load
virtio_pci 3 Load
nvme 3 Load
nvme_core 3 Load
virtio_pci_legacy_dev 3 Load
virtio_pci_modern_dev 3 Load
t10_pi 3 Load
virtio 3 Load
crc32_pclmul 6 Load
crc64_rocksoft 3 Load
crc32c_intel 40 Load
virtio_ring 3 Load
crc64 3 Load
The following screen shot, of a simple 8vcpu 8 GiB KVM guest with the
next patch in this series applied, shows 226.53 MiB are wasted in virtual
memory allocations which due to duplicate module requests during boot.
It also shows an average module memory size of 167.10 KiB and an an
average module .text + .init.text size of 61.13 KiB. The end shows all
modules which were detected as duplicate requests and whether or not
they failed early after just the first kernel_read*() call or late after
we've already allocated the private space for the module in
layout_and_allocate(). A system with module decompression would reveal
more wasted virtual memory space.
We should put effort now into identifying the source of these duplicate
module requests and trimming these down as much possible. Larger systems
will obviously show much more wasted virtual memory allocations.
root@kmod ~ # cat /sys/kernel/debug/modules/stats
Mods ever loaded 67
Mods failed on kread 0
Mods failed on decompress 0
Mods failed on becoming 83
Mods failed on load 16
Total module size 11464704
Total mod text size 4194304
Failed kread bytes 0
Failed decompress bytes 0
Failed becoming bytes 228959096
Failed kmod bytes 8578080
Virtual mem wasted bytes 237537176
Average mod size 171115
Average mod text size 62602
Avg fail becoming bytes 2758544
Average fail load bytes 536130
Duplicate failed modules:
module-name How-many-times Reason
kvm_intel 7 Becoming
kvm 7 Becoming
irqbypass 6 Becoming & Load
crct10dif_pclmul 7 Becoming & Load
ghash_clmulni_intel 7 Becoming & Load
sha512_ssse3 6 Becoming & Load
sha512_generic 7 Becoming & Load
aesni_intel 7 Becoming
crypto_simd 7 Becoming & Load
cryptd 3 Becoming & Load
evdev 1 Becoming
serio_raw 1 Becoming
nvme 3 Becoming
nvme_core 3 Becoming
t10_pi 3 Becoming
virtio_pci 3 Becoming
crc32_pclmul 6 Becoming & Load
crc64_rocksoft 3 Becoming
crc32c_intel 3 Becoming
virtio_pci_modern_dev 2 Becoming
virtio_pci_legacy_dev 1 Becoming
crc64 2 Becoming
virtio 2 Becoming
virtio_ring 2 Becoming
[0] https://github.com/ColinIanKing/stress-ng.git
[1] echo 0 > /proc/sys/vm/oom_dump_tasks
./stress-ng --module 100 --module-name xfs
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Donald Dutile <ddutile@redhat.com>
MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/3910
JIRA: https://issues.redhat.com/browse/RHEL-25103
MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/3910
Depends: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/3847
The primary purpose of this MR is to backport those upstream workqueue
commits which enables ordered workqueues and rescuers to follow
changes in workqueue unbound cpumask which is necessary to make sure
that isolated CPUs won't be disturbed due to unbound work items being
handled by those CPUs.
These upstream commits were merged into the v6.9 kernel which also
contains some major changes in workqueue code. This makes the required
commits dependent on some of the v6.9 workqueue commits. It is less risky
to sync the workqueue code up to v6.9 instead of selective backports
of some dependent commits. This MR also includes some miscellaneous
commits in other subsystems due to changes in the underlying workqueue
implementations.
A follow-up proactive workqueue fixes MR will be created later on,
if necessary.
Signed-off-by: Waiman Long <longman@redhat.com>
Approved-by: Tony Camuso <tcamuso@redhat.com>
Approved-by: Steve Best <sbest@redhat.com>
Approved-by: Vladis Dronov <vdronov@redhat.com>
Approved-by: Prarit Bhargava <prarit@redhat.com>
Approved-by: Wander Lairson Costa <wander@redhat.com>
Approved-by: Phil Auld <pauld@redhat.com>
Approved-by: Radu Rendec <rrendec@redhat.com>
Approved-by: Chris von Recklinghausen <crecklin@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>
Merged-by: Lucas Zampieri <lzampier@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-40250
commit 03699f271de1f4df6369cd379506539cd7d590d3
Author: Kees Cook <keescook@chromium.org>
Date: Fri Sep 2 14:33:44 2022 -0700
string: Rewrite and add more kern-doc for the str*() functions
While there were varying degrees of kern-doc for various str*()-family
functions, many needed updating and clarification, or to just be
entirely written. Update (and relocate) existing kern-doc and add missing
functions, sadly shaking my head at how many times I have written "Do
not use this function". Include the results in the core kernel API doc.
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Andy Shevchenko <andy@kernel.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-hardening@vger.kernel.org
Tested-by: Akira Yokosawa <akiyks@gmail.com>
Link: https://lore.kernel.org/lkml/9b0cf584-01b3-3013-b800-1ef59fe82476@gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-26183
Conflicts:
Documentation/ABI/testing/sysfs-devices-system-cpu -
The crash_hotplug text was added to the end of the file
in upstream, so I did the same here.
include/linux/kexec.h - minor context differences
commit 88a6f89944216b028d3872b0cec0f51a2f955460
Author: Eric DeVolder <eric.devolder@oracle.com>
Date: Thu, 24 Aug 2023 16:25:14 +0000
Introduce the crash_hotplug attribute for memory and CPUs for use by
userspace. These attributes directly facilitate the udev rule for
managing userspace re-loading of the crash kernel upon hot un/plug
changes.
For memory, expose the crash_hotplug attribute to the
/sys/devices/system/memory directory. For example:
# udevadm info --attribute-walk /sys/devices/system/memory/memory81
looking at device '/devices/system/memory/memory81':
KERNEL=="memory81"
SUBSYSTEM=="memory"
DRIVER==""
ATTR{online}=="1"
ATTR{phys_device}=="0"
ATTR{phys_index}=="00000051"
ATTR{removable}=="1"
ATTR{state}=="online"
ATTR{valid_zones}=="Movable"
looking at parent device '/devices/system/memory':
KERNELS=="memory"
SUBSYSTEMS==""
DRIVERS==""
ATTRS{auto_online_blocks}=="offline"
ATTRS{block_size_bytes}=="8000000"
ATTRS{crash_hotplug}=="1"
For CPUs, expose the crash_hotplug attribute to the
/sys/devices/system/cpu directory. For example:
# udevadm info --attribute-walk /sys/devices/system/cpu/cpu0
looking at device '/devices/system/cpu/cpu0':
KERNEL=="cpu0"
SUBSYSTEM=="cpu"
DRIVER=="processor"
ATTR{crash_notes}=="277c38600"
ATTR{crash_notes_size}=="368"
ATTR{online}=="1"
looking at parent device '/devices/system/cpu':
KERNELS=="cpu"
SUBSYSTEMS==""
DRIVERS==""
ATTRS{crash_hotplug}=="1"
ATTRS{isolated}==""
ATTRS{kernel_max}=="8191"
ATTRS{nohz_full}==" (null)"
ATTRS{offline}=="4-7"
ATTRS{online}=="0-3"
ATTRS{possible}=="0-7"
ATTRS{present}=="0-3"
With these sysfs attributes in place, it is possible to efficiently
instruct the udev rule to skip crash kernel reloading for kernels
configured with crash hotplug support.
For example, the following is the proposed udev rule change for RHEL
system 98-kexec.rules (as the first lines of the rule file):
# The kernel updates the crash elfcorehdr for CPU and memory changes
SUBSYSTEM=="cpu", ATTRS{crash_hotplug}=="1", GOTO="kdump_reload_end"
SUBSYSTEM=="memory", ATTRS{crash_hotplug}=="1", GOTO="kdump_reload_end"
When examined in the context of 98-kexec.rules, the above rules test if
crash_hotplug is set, and if so, the userspace initiated
unload-then-reload of the crash kernel is skipped.
CPU and memory checks are separated in accordance with CONFIG_HOTPLUG_CPU
and CONFIG_MEMORY_HOTPLUG kernel config options. If an architecture
supports, for example, memory hotplug but not CPU hotplug, then the
/sys/devices/system/memory/crash_hotplug attribute file is present, but
the /sys/devices/system/cpu/crash_hotplug attribute file will NOT be
present. Thus the udev rule skips userspace processing of memory hot
un/plug events, but the udev rule will evaluate false for CPU events, thus
allowing userspace to process CPU hot un/plug events (ie the
unload-then-reload of the kdump capture kernel).
Link: https://lkml.kernel.org/r/20230814214446.6659-5-eric.devolder@oracle.com
Signed-off-by: Eric DeVolder <eric.devolder@oracle.com>
Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Hari Bathini <hbathini@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Akhil Raj <lf32.dev@gmail.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mark Langsdorf <mlangsdo@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-25103
commit 3bc1e711c26bff01d41ad71145ecb8dcb4412576
Author: Tejun Heo <tj@kernel.org>
Date: Mon, 5 Feb 2024 14:19:10 -1000
workqueue: Don't implicitly make UNBOUND workqueues w/ @max_active==1 ordered
5c0338c687 ("workqueue: restore WQ_UNBOUND/max_active==1 to be ordered")
automoatically promoted UNBOUND workqueues w/ @max_active==1 to ordered
workqueues because UNBOUND workqueues w/ @max_active==1 used to be the way
to create ordered workqueues and the new NUMA support broke it. These
problems can be subtle and the fact that they can only trigger on NUMA
machines made them even more difficult to debug.
However, overloading the UNBOUND allocation interface this way creates other
issues. It's difficult to tell whether a given workqueue actually needs to
be ordered and users that legitimately want a min concurrency level wq
unexpectedly gets an ordered one instead. With planned UNBOUND workqueue
udpates to improve execution locality and more prevalence of chiplet designs
which can benefit from such improvements, this isn't a state we wanna be in
forever.
There aren't that many UNBOUND w/ @max_active==1 users in the tree and the
preceding patches audited all and converted them to
alloc_ordered_workqueue() as appropriate. This patch removes the implicit
promotion of UNBOUND w/ @max_active==1 workqueues to ordered ones.
v2: v1 patch incorrectly dropped !list_empty(&wq->pwqs) condition in
apply_workqueue_attrs_locked() which spuriously triggers WARNING and
fails workqueue creation. Fix it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: kernel test robot <oliver.sang@intel.com>
Link: https://lore.kernel.org/oe-lkp/202304251050.45a5df1f-oliver.sang@intel.com
Signed-off-by: Waiman Long <longman@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-25103
Conflicts: A minor context diff in kernel/workqueue.c due to missing
upstream commit 68279f9c9f59 ("treewide: mark stuff as
__ro_after_init").
commit 4cb1ef64609f9b0254184b2947824f4b46ccab22
Author: Tejun Heo <tj@kernel.org>
Date: Sun, 4 Feb 2024 11:28:06 -1000
workqueue: Implement BH workqueues to eventually replace tasklets
The only generic interface to execute asynchronously in the BH context is
tasklet; however, it's marked deprecated and has some design flaws such as
the execution code accessing the tasklet item after the execution is
complete which can lead to subtle use-after-free in certain usage scenarios
and less-developed flush and cancel mechanisms.
This patch implements BH workqueues which share the same semantics and
features of regular workqueues but execute their work items in the softirq
context. As there is always only one BH execution context per CPU, none of
the concurrency management mechanisms applies and a BH workqueue can be
thought of as a convenience wrapper around softirq.
Except for the inability to sleep while executing and lack of max_active
adjustments, BH workqueues and work items should behave the same as regular
workqueues and work items.
Currently, the execution is hooked to tasklet[_hi]. However, the goal is to
convert all tasklet users over to BH workqueues. Once the conversion is
complete, tasklet can be removed and BH workqueues can directly take over
the tasklet softirqs.
system_bh[_highpri]_wq are added. As queue-wide flushing doesn't exist in
tasklet, all existing tasklet users should be able to use the system BH
workqueues without creating their own workqueues.
v3: - Add missing interrupt.h include.
v2: - Instead of using tasklets, hook directly into its softirq action
functions - tasklet[_hi]_action(). This is slightly cheaper and closer
to the eventual code structure we want to arrive at. Suggested by Lai.
- Lai also pointed out several places which need NULL worker->task
handling or can use clarification. Updated.
Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/CAHk-=wjDW53w4-YcSmgKC5RruiRLHmJ1sXeYdp_ZgVoBw=5byA@mail.gmail.com
Tested-by: Allen Pais <allen.lkml@gmail.com>
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Waiman Long <longman@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-25103
commit 22160b08d88898898b2bb99282663cdf3caa5c1c
Author: attreyee-muk <tintinm2017@gmail.com>
Date: Thu, 11 Jan 2024 00:27:47 +0530
Documentation/core-api: fix spelling mistake in workqueue
Correct to "following" from "followings" in the sentence "The followings
are the read bandwidths and CPU utilizations depending on different affinity
scope settings on ``kcryptd`` measured over five runs."
Signed-off-by: Attreyee Mukherjee <tintinm2017@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240110185746.24974-1-tintinm2017@gmail.com
Signed-off-by: Waiman Long <longman@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-25103
commit 523a301e66afd1ea9856660bcf3cee3a7c84c6dd
Author: Tejun Heo <tj@kernel.org>
Date: Mon, 7 Aug 2023 15:57:25 -1000
workqueue: Make default affinity_scope dynamically updatable
While workqueue.default_affinity_scope is writable, it only affects
workqueues which are created afterwards and isn't very useful. Instead,
let's introduce explicit "default" scope and update the effective scope
dynamically when workqueue.default_affinity_scope is changed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Waiman Long <longman@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-25103
commit 7dbf15c5c05e835d488e0fee49a35b0f23452e45
Author: Tejun Heo <tj@kernel.org>
Date: Mon, 7 Aug 2023 15:57:25 -1000
workqueue: Add "Affinity Scopes and Performance" section to documentation
With affinity scopes and their strictness setting added, unbound workqueues
should now be able to cover wide variety of configurations and use cases.
Unfortunately, the performance picture is not entirely straight-forward due
to a trade-off between efficiency and work-conservation in some situations
necessitating manual configuration.
This patch adds "Affinity Scopes and Performance" section to
Documentation/core-api/workqueue.rst which illustrates the trade-off with a
set of experiments and provides some guidelines.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Waiman Long <longman@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-25103
commit 8639ecebc9b1796d7074751a350462f5e1c61cd4
Author: Tejun Heo <tj@kernel.org>
Date: Mon, 7 Aug 2023 15:57:25 -1000
workqueue: Implement non-strict affinity scope for unbound workqueues
An unbound workqueue can be served by multiple worker_pools to improve
locality. The segmentation is achieved by grouping CPUs into pods. By
default, the cache boundaries according to cpus_share_cache() define the
CPUs are grouped. Let's a workqueue is allowed to run on all CPUs and the
system has two L3 caches. The workqueue would be mapped to two worker_pools
each serving one L3 cache domains.
While this improves locality, because the pod boundaries are strict, it
limits the total bandwidth a given issuer can consume. For example, let's
say there is a thread pinned to a CPU issuing enough work items to saturate
the whole machine. With the machine segmented into two pods, no matter how
many work items it issues, it can only use half of the CPUs on the system.
While this limitation has existed for a very long time, it wasn't very
pronounced because the affinity grouping used to be always by NUMA nodes.
With cache boundaries as the default and support for even finer grained
scopes (smt and cpu), it is now an a lot more pressing problem.
This patch implements non-strict affinity scope where the pod boundaries
aren't enforced strictly. Going back to the previous example, the workqueue
would still be mapped to two worker_pools; however, the affinity enforcement
would be soft. The workers in both pools would have their cpus_allowed set
to the whole machine thus allowing the scheduler to migrate them anywhere on
the machine. However, whenever an idle worker is woken up, the workqueue
code asks the scheduler to bring back the task within the pod if the worker
is outside. ie. work items start executing within its affinity scope but can
be migrated outside as the scheduler sees fit. This removes the hard cap on
utilization while maintaining the benefits of affinity scopes.
After the earlier ->__pod_cpumask changes, the implementation is pretty
simple. When non-strict which is the new default:
* pool_allowed_cpus() returns @pool->attrs->cpumask instead of
->__pod_cpumask so that the workers are allowed to run on any CPU that
the associated workqueues allow.
* If the idle worker task's ->wake_cpu is outside the pod, kick_pool() sets
the field to a CPU within the pod.
This would be the first use of task_struct->wake_cpu outside scheduler
proper, so it isn't clear whether this would be acceptable. However, other
methods of migrating tasks are significantly more expensive and are likely
prohibitively so if we want to do this on every work item. This needs
discussion with scheduler folks.
There is also a race window where setting ->wake_cpu wouldn't be effective
as the target task is still on CPU. However, the window is pretty small and
this being a best-effort optimization, it doesn't seem to warrant more
complexity at the moment.
While the non-strict cache affinity scopes seem to be the best option, the
performance picture interacts with the affinity scope and is a bit
complicated to fully discuss in this patch, so the behavior is made easily
selectable through wqattrs and sysfs and the next patch will add
documentation to discuss performance implications.
v2: pool->attrs->affn_strict is set to true for per-cpu worker_pools.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Waiman Long <longman@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-25103
commit 63c5484e74952f60f5810256bd69814d167b8d22
Author: Tejun Heo <tj@kernel.org>
Date: Mon, 7 Aug 2023 15:57:24 -1000
workqueue: Add multiple affinity scopes and interface to select them
Add three more affinity scopes - WQ_AFFN_CPU, SMT and CACHE - and make CACHE
the default. The code changes to actually add the additional scopes are
trivial.
Also add module parameter "workqueue.default_affinity_scope" to override the
default scope and "affinity_scope" sysfs file to configure it per workqueue.
wq_dump.py and documentations are updated accordingly.
This enables significant flexibility in configuring how unbound workqueues
behave. If affinity scope is set to "cpu", it'll behave close to a per-cpu
workqueue. On the other hand, "system" removes all locality boundaries.
Many modern machines have multiple L3 caches often while being mostly
uniform in terms of memory access. Thus, workqueue's previous behavior of
spreading work items in each NUMA node had negative performance implications
from unncessarily crossing L3 boundaries between issue and execution.
However, picking a finer grained affinity scope also has a downside in that
an issuer in one group can't utilize CPUs in other groups.
While dependent on the specifics of workload, there's usually a noticeable
penalty in crossing L3 boundaries, so let's default to CACHE. This issue
will be further addressed and documented with examples in future patches.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Waiman Long <longman@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-25103
commit 7f7dc377a3b2bbaa8cf8941587c228eab4bd82ec
Author: Tejun Heo <tj@kernel.org>
Date: Mon, 7 Aug 2023 15:57:24 -1000
workqueue: Add tools/workqueue/wq_dump.py which prints out workqueue configuration
Lack of visibility has always been a pain point for workqueues. While the
recently added wq_monitor.py improved the situation, it's still difficult to
understand what worker pools are active in the system, how workqueues map to
them and why. The lack of visibility into how workqueues are configured is
going to become more noticeable as workqueue improves locality awareness and
provides more mechanisms to customize locality related behaviors.
Now that the basic framework for more flexible locality support is in place,
this is a good time to improve the situation. This patch adds
tools/workqueues/wq_dump.py which prints out the topology configuration,
worker pools and how workqueues are mapped to pools. Read the command's help
message for more details.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Waiman Long <longman@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-25103
commit 636b927eba5bc633753f8eb80f35e1d5be806e51
Author: Tejun Heo <tj@kernel.org>
Date: Mon, 7 Aug 2023 15:57:23 -1000
workqueue: Make unbound workqueues to use per-cpu pool_workqueues
A pwq (pool_workqueue) represents an association between a workqueue and a
worker_pool. When a work item is queued, the workqueue selects the pwq to
use, which in turn determines the pool, and queues the work item to the pool
through the pwq. pwq is also what implements the maximum concurrency limit -
@max_active.
As a per-cpu workqueue should be assocaited with a different worker_pool on
each CPU, it always had per-cpu pwq's that are accessed through wq->cpu_pwq.
However, unbound workqueues were sharing a pwq within each NUMA node by
default. The sharing has several downsides:
* Because @max_active is per-pwq, the meaning of @max_active changes
depending on the machine configuration and whether workqueue NUMA locality
support is enabled.
* Makes per-cpu and unbound code deviate.
* Gets in the way of making workqueue CPU locality awareness more flexible.
This patch makes unbound workqueues use per-cpu pwq's the same way per-cpu
workqueues do by making the following changes:
* wq->numa_pwq_tbl[] is removed and unbound workqueues now use wq->cpu_pwq
just like per-cpu workqueues. wq->cpu_pwq is now RCU protected for unbound
workqueues.
* numa_pwq_tbl_install() is renamed to install_unbound_pwq() and installs
the specified pwq to the target CPU's wq->cpu_pwq.
* apply_wqattrs_prepare() now always allocates a separate pwq for each CPU
unless the workqueue is ordered. If ordered, all CPUs use wq->dfl_pwq.
This makes the return value of wq_calc_node_cpumask() unnecessary. It now
returns void.
* @max_active now means the same thing for both per-cpu and unbound
workqueues. WQ_UNBOUND_MAX_ACTIVE now equals WQ_MAX_ACTIVE and
documentation is updated accordingly. WQ_UNBOUND_MAX_ACTIVE is no longer
used in workqueue implementation and will be removed later.
* All unbound pwq operations which used to be per-numa-node are now per-cpu.
For most unbound workqueue users, this shouldn't cause noticeable changes.
Work item issue and completion will be a small bit faster, flush_workqueue()
would become a bit more expensive, and the total concurrency limit would
likely become higher. All @max_active==1 use cases are currently being
audited for conversion into alloc_ordered_workqueue() and they shouldn't be
affected once the audit and conversion is complete.
One area where the behavior change may be more noticeable is
workqueue_congested() as the reported congestion state is now per CPU
instead of NUMA node. There are only two users of this interface -
drivers/infiniband/hw/hfi1 and net/smc. Maintainers of both subsystems are
cc'd. Inputs on the behavior change would be very much appreciated.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Karsten Graul <kgraul@linux.ibm.com>
Cc: Wenjia Zhang <wenjia@linux.ibm.com>
Cc: Jan Karcher <jaka@linux.ibm.com>
Signed-off-by: Waiman Long <longman@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-25103
commit 8a1dd1e547c1a037692e7a6da6a76108108c72b1
Author: Tejun Heo <tj@kernel.org>
Date: Wed, 17 May 2023 17:02:09 -1000
workqueue: Track and monitor per-workqueue CPU time usage
Now that wq_worker_tick() is there, we can easily track the rough CPU time
consumption of each workqueue by charging the whole tick whenever a tick
hits an active workqueue. While not super accurate, it provides reasonable
visibility into the workqueues that consume a lot of CPU cycles.
wq_monitor.py is updated to report the per-workqueue CPU times.
v2: wq_monitor.py was using "cputime" as the key when outputting in json
format. Use "cpu_time" instead for consistency with other fields.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Waiman Long <longman@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-25103
commit 616db8779b1e3f93075df691432cccc5ef3c3ba0
Author: Tejun Heo <tj@kernel.org>
Date: Wed, 17 May 2023 17:02:08 -1000
workqueue: Automatically mark CPU-hogging work items CPU_INTENSIVE
If a per-cpu work item hogs the CPU, it can prevent other work items from
starting through concurrency management. A per-cpu workqueue which intends
to host such CPU-hogging work items can choose to not participate in
concurrency management by setting %WQ_CPU_INTENSIVE; however, this can be
error-prone and difficult to debug when missed.
This patch adds an automatic CPU usage based detection. If a
concurrency-managed work item consumes more CPU time than the threshold
(10ms by default) continuously without intervening sleeps, wq_worker_tick()
which is called from scheduler_tick() will detect the condition and
automatically mark it CPU_INTENSIVE.
The mechanism isn't foolproof:
* Detection depends on tick hitting the work item. Getting preempted at the
right timings may allow a violating work item to evade detection at least
temporarily.
* nohz_full CPUs may not be running ticks and thus can fail detection.
* Even when detection is working, the 10ms detection delays can add up if
many CPU-hogging work items are queued at the same time.
However, in vast majority of cases, this should be able to detect violations
reliably and provide reasonable protection with a small increase in code
complexity.
If some work items trigger this condition repeatedly, the bigger problem
likely is the CPU being saturated with such per-cpu work items and the
solution would be making them UNBOUND. The next patch will add a debug
mechanism to help spot such cases.
v4: Documentation for workqueue.cpu_intensive_thresh_us added to
kernel-parameters.txt.
v3: Switch to use wq_worker_tick() instead of hooking into preemptions as
suggested by Peter.
v2: Lai pointed out that wq_worker_stopping() also needs to be called from
preemption and rtlock paths and an earlier patch was updated
accordingly. This patch adds a comment describing the risk of infinte
recursions and how they're avoided.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Waiman Long <longman@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-25103
commit 725e8ec59c56c65fb92e343c10a8842cd0d4f194
Author: Tejun Heo <tj@kernel.org>
Date: Wed, 17 May 2023 17:02:08 -1000
workqueue: Add pwq->stats[] and a monitoring script
Currently, the only way to peer into workqueue operations is through
tracing. While possible, it isn't easy or convenient to monitor
per-workqueue behaviors over time this way. Let's add pwq->stats[] that
track relevant events and a drgn monitoring script -
tools/workqueue/wq_monitor.py.
It's arguable whether this needs to be configurable. However, it currently
only has several counters and the runtime overhead shouldn't be noticeable
given that they're on pwq's which are per-cpu on per-cpu workqueues and
per-numa-node on unbound ones. Let's keep it simple for the time being.
v2: Patch reordered to earlier with fewer fields. Field will be added back
gradually. Help message improved.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Waiman Long <longman@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-25103
commit f9eaaa82b474350aa8436d15a7ae150a3c8b9d5c
Author: Boqun Feng <boqun.feng@gmail.com>
Date: Fri, 22 Oct 2021 08:42:08 +0800
workqueue: doc: Call out the non-reentrance conditions
The current doc of workqueue API suggests that work items are
non-reentrant: any work item is guaranteed to be executed by at most one
worker system-wide at any given time. However this is not true, the
following case can cause a work item W executed by two workers at
the same time:
queue_work_on(0, WQ1, W);
// after a worker picks up W and clear the pending bit
queue_work_on(1, WQ2, W);
// workers on CPU0 and CPU1 will execute W in the same time.
, which means the non-reentrance of a work item is conditional, and
Lai Jiangshan provided a nice summary[1] of the conditions, therefore
use it to describe a work item instance and improve the doc.
[1]: https://lore.kernel.org/lkml/CAJhGHyDudet_xyNk=8xnuO2==o-u06s0E0GZVP4Q67nmQ84Ceg@mail.gmail.com/
Suggested-by: Matthew Wilcox <willy@infradead.org>
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Waiman Long <longman@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-27741
commit ae65a5211d90e54ae604012ce9cf234c48780929
Author: Vlastimil Babka <vbabka@suse.cz>
Date: Thu Mar 2 16:01:00 2023 +0100
mm/slab: document kfree() as allowed for kmem_cache_alloc() objects
This will make it easier to free objects in situations when they can
come from either kmalloc() or kmem_cache_alloc(), and also allow
kfree_rcu() for freeing objects from kmem_cache_alloc().
For the SLAB and SLUB allocators this was always possible so with SLOB
gone, we can document it as supported.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Chris von Recklinghausen <crecklin@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-27741
commit 4c85c0be3d7a9a7ffe48bfe0954eacc0ba9d3c75
Author: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Date: Mon Jan 30 13:25:13 2023 +0900
mm, printk: introduce new format %pGt for page_type
%pGp format is used to display 'flags' field of a struct page. However,
some page flags (i.e. PG_buddy, see page-flags.h for more details) are
stored in page_type field. To display human-readable output of page_type,
introduce %pGt format.
It is important to note the meaning of bits are different in page_type.
if page_type is 0xffffffff, no flags are set. Setting PG_buddy
(0x00000080) flag results in a page_type of 0xffffff7f. Clearing a bit
actually means setting a flag. Bits in page_type are inverted when
displaying type names.
Only values for which page_type_has_type() returns true are considered as
page_type, to avoid confusion with mapcount values. if it returns false,
only raw values are displayed and not page type names.
Link: https://lkml.kernel.org/r/20230130042514.2418-3-42.hyeyoo@gmail.com
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Reviewed-by: Petr Mladek <pmladek@suse.com> [vsprintf part]
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Chris von Recklinghausen <crecklin@redhat.com>
commit baa489fabd01596d5426d6e112b34ba5fb59ab82
Author: SeongJae Park <sj@kernel.org>
Date: Tue Jan 3 18:07:53 2023 +0000
selftests/vm: rename selftests/vm to selftests/mm
Rename selftets/vm to selftests/mm for being more consistent with the
code, documentation, and tools directories, and won't be confused with
virtual machines.
[sj@kernel.org: convert missing vm->mm changes]
Link: https://lkml.kernel.org/r/20230107230643.252273-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20230103180754.129637-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
JIRA: https://issues.redhat.com/browse/RHEL-5617
Signed-off-by: Nico Pache <npache@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-13724
commit 5bdeb6f5c7b94f653183f08eca8a08022b2efac6
Author: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Date: Tue Jul 25 13:49:56 2023 +0300
Documentation: core-api: Drop :export: for int_log.h
The :export: keyword makes sense only for C-files, where EXPORT_SYMBOL()
might appear. Otherwise kernel-doc may not produce anything out of this
file.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: f97fa3dcb2db ("lib/math: Move dvb_math.c into lib/math/int_log.c")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20230725104956.47806-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Jaroslav Kysela <jkysela@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-13724
commit f97fa3dcb2db02013e6904c032a1d2d45707ee40
Author: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Date: Mon Jul 3 16:52:08 2023 +0300
lib/math: Move dvb_math.c into lib/math/int_log.c
Some existing and new users may benefit from the intlog2() and
intlog10() APIs, make them wide available.
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Acked-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Link: https://lore.kernel.org/r/20230619172019.21457-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20230703135211.87416-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Jaroslav Kysela <jkysela@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-15512
commit e59e74dc48a309cb848ffc3d76a0d61aa6803c05
Author: Thomas Gleixner <tglx@linutronix.de>
Date: Fri May 12 23:07:04 2023 +0200
x86/topology: Remove CPU0 hotplug option
This was introduced together with commit e1c467e690 ("x86, hotplug: Wake
up CPU0 via NMI instead of INIT, SIPI, SIPI") to eventually support
physical hotplug of CPU0:
"We'll change this code in the future to wake up hard offlined CPU0 if
real platform and request are available."
11 years later this has not happened and physical hotplug is not officially
supported. Remove the cruft.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com> # Steam Deck
Link: https://lore.kernel.org/r/20230512205255.715707999@linutronix.de
Signed-off-by: David Arcari <darcari@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-1848
commit 94688e8eb453e616098cb930e5f6fed4a6ea2dfa
Author: Matthew Wilcox (Oracle) <willy@infradead.org>
Date: Wed Jan 11 14:28:47 2023 +0000
mm: remove folio_pincount_ptr() and head_compound_pincount()
We can use folio->_pincount directly, since all users are guarded by tests
of compound/large.
Link: https://lkml.kernel.org/r/20230111142915.1001531-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Chris von Recklinghausen <crecklin@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-1848
commit def76fd549c513bb90278a8d6d0fe3ef3faa20a7
Author: Miaohe Lin <linmiaohe@huawei.com>
Date: Fri Sep 16 15:22:56 2022 +0800
mm/page_alloc: remove obsolete gfpflags_normal_context()
Since commit dacb5d8875cc ("tcp: fix page frag corruption on page fault"),
there's no caller of gfpflags_normal_context(). Remove it as this helper
is strictly tied to the sk page frag usage and there won't be other user
in the future.
[linmiaohe@huawei.com: fix htmldocs]
Link: https://lkml.kernel.org/r/1bc55727-9b66-0e9e-c306-f10c4716ea89@huawei.com
Link: https://lkml.kernel.org/r/20220916072257.9639-16-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Chris von Recklinghausen <crecklin@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-1848
commit 7343f2b0db4961d9f386e685e651c663dc763d0c
Author: Yury Norov <yury.norov@gmail.com>
Date: Wed Jul 6 08:52:24 2022 -0700
headers/deps: mm: align MANITAINERS and Docs with new gfp.h structure
After moving gfp types out of gfp.h, we have to align MAINTAINERS
and Docs, to avoid warnings like this:
>> include/linux/gfp.h:1: warning: 'Page mobility and placement hints' not found
>> include/linux/gfp.h:1: warning: 'Watermark modifiers' not found
>> include/linux/gfp.h:1: warning: 'Reclaim modifiers' not found
>> include/linux/gfp.h:1: warning: 'Useful GFP flag combinations' not found
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Chris von Recklinghausen <crecklin@redhat.com>
Conflicts: drop changes to arch/alpha/include/asm/io.h - unsupported config
Bugzilla: https://bugzilla.redhat.com/2160210
commit 4313a24985f00340eeb591fd66aa2b257b9e0a69
Author: Arnd Bergmann <arnd@arndb.de>
Date: Mon May 23 21:59:02 2022 +0200
arch/*/: remove CONFIG_VIRT_TO_BUS
All architecture-independent users of virt_to_bus() and bus_to_virt()
have been fixed to use the dma mapping interfaces or have been
removed now. This means the definitions on most architectures, and the
CONFIG_VIRT_TO_BUS symbol are now obsolete and can be removed.
The only exceptions to this are a few network and scsi drivers for m68k
Amiga and VME machines and ppc32 Macintosh. These drivers work correctly
with the old interfaces and are probably not worth changing.
On alpha and parisc, virt_to_bus() were still used in asm/floppy.h.
alpha can use isa_virt_to_bus() like x86 does, and parisc can just
open-code the virt_to_phys() here, as this is architecture specific
code.
I tried updating the bus-virt-phys-mapping.rst documentation, which
started as an email from Linus to explain some details of the Linux-2.0
driver interfaces. The bits about virt_to_bus() were declared obsolete
backin 2000, and the rest is not all that relevant any more, so in the
end I just decided to remove the file completely.
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Acked-by: Helge Deller <deller@gmx.de> # parisc
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Chris von Recklinghausen <crecklin@redhat.com>
Conflicts: drop changes to arch/loongarch/Kconfig - unsupported config
Bugzilla: https://bugzilla.redhat.com/2160210
commit ee65728e103bb7dd99d8604bf6c7aa89c7d7e446
Author: Mike Rapoport <rppt@kernel.org>
Date: Mon Jun 27 09:00:26 2022 +0300
docs: rename Documentation/vm to Documentation/mm
so it will be consistent with code mm directory and with
Documentation/admin-guide/mm and won't be confused with virtual machines.
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Tested-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Acked-by: Wu XiangCheng <bobwxc@email.cn>
Signed-off-by: Chris von Recklinghausen <crecklin@redhat.com>
Conflicts:
lib/Makefile: slight makefile conflict
commit 54a611b605901c7d5d05b6b8f5d04a6ceb0962aa
Author: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Tue Sep 6 19:48:39 2022 +0000
Maple Tree: add new data structure
Patch series "Introducing the Maple Tree"
The maple tree is an RCU-safe range based B-tree designed to use modern
processor cache efficiently. There are a number of places in the kernel
that a non-overlapping range-based tree would be beneficial, especially
one with a simple interface. If you use an rbtree with other data
structures to improve performance or an interval tree to track
non-overlapping ranges, then this is for you.
The tree has a branching factor of 10 for non-leaf nodes and 16 for leaf
nodes. With the increased branching factor, it is significantly shorter
than the rbtree so it has fewer cache misses. The removal of the linked
list between subsequent entries also reduces the cache misses and the need
to pull in the previous and next VMA during many tree alterations.
The first user that is covered in this patch set is the vm_area_struct,
where three data structures are replaced by the maple tree: the augmented
rbtree, the vma cache, and the linked list of VMAs in the mm_struct. The
long term goal is to reduce or remove the mmap_lock contention.
The plan is to get to the point where we use the maple tree in RCU mode.
Readers will not block for writers. A single write operation will be
allowed at a time. A reader re-walks if stale data is encountered. VMAs
would be RCU enabled and this mode would be entered once multiple tasks
are using the mm_struct.
Davidlor said
: Yes I like the maple tree, and at this stage I don't think we can ask for
: more from this series wrt the MM - albeit there seems to still be some
: folks reporting breakage. Fundamentally I see Liam's work to (re)move
: complexity out of the MM (not to say that the actual maple tree is not
: complex) by consolidating the three complimentary data structures very
: much worth it considering performance does not take a hit. This was very
: much a turn off with the range locking approach, which worst case scenario
: incurred in prohibitive overhead. Also as Liam and Matthew have
: mentioned, RCU opens up a lot of nice performance opportunities, and in
: addition academia[1] has shown outstanding scalability of address spaces
: with the foundation of replacing the locked rbtree with RCU aware trees.
A similar work has been discovered in the academic press
https://pdos.csail.mit.edu/papers/rcuvm:asplos12.pdf
Sheer coincidence. We designed our tree with the intention of solving the
hardest problem first. Upon settling on a b-tree variant and a rough
outline, we researched ranged based b-trees and RCU b-trees and did find
that article. So it was nice to find reassurances that we were on the
right path, but our design choice of using ranges made that paper unusable
for us.
This patch (of 70):
The maple tree is an RCU-safe range based B-tree designed to use modern
processor cache efficiently. There are a number of places in the kernel
that a non-overlapping range-based tree would be beneficial, especially
one with a simple interface. If you use an rbtree with other data
structures to improve performance or an interval tree to track
non-overlapping ranges, then this is for you.
The tree has a branching factor of 10 for non-leaf nodes and 16 for leaf
nodes. With the increased branching factor, it is significantly shorter
than the rbtree so it has fewer cache misses. The removal of the linked
list between subsequent entries also reduces the cache misses and the need
to pull in the previous and next VMA during many tree alterations.
The first user that is covered in this patch set is the vm_area_struct,
where three data structures are replaced by the maple tree: the augmented
rbtree, the vma cache, and the linked list of VMAs in the mm_struct. The
long term goal is to reduce or remove the mmap_lock contention.
The plan is to get to the point where we use the maple tree in RCU mode.
Readers will not block for writers. A single write operation will be
allowed at a time. A reader re-walks if stale data is encountered. VMAs
would be RCU enabled and this mode would be entered once multiple tasks
are using the mm_struct.
There is additional BUG_ON() calls added within the tree, most of which
are in debug code. These will be replaced with a WARN_ON() call in the
future. There is also additional BUG_ON() calls within the code which
will also be reduced in number at a later date. These exist to catch
things such as out-of-range accesses which would crash anyways.
Link: https://lkml.kernel.org/r/20220906194824.2110408-1-Liam.Howlett@oracle.com
Link: https://lkml.kernel.org/r/20220906194824.2110408-2-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Tested-by: David Howells <dhowells@redhat.com>
Tested-by: Sven Schnelle <svens@linux.ibm.com>
Tested-by: Yu Zhao <yuzhao@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2166668
Signed-off-by: Nico Pache <npache@redhat.com>
Bugzilla: https://bugzilla.redhat.com/2166911
Upstream Status: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
commit 3dc6ffae2da201284cb24af66af77ee0bbb2efaa
Author: Kurt Kanzenbach <kurt@linutronix.de>
Date: Thu Apr 14 11:18:03 2022 +0200
timekeeping: Introduce fast accessor to clock tai
Introduce fast/NMI safe accessor to clock tai for tracing. The Linux kernel
tracing infrastructure has support for using different clocks to generate
timestamps for trace events. Especially in TSN networks it's useful to have TAI
as trace clock, because the application scheduling is done in accordance to the
network time, which is based on TAI. With a tai trace_clock in place, it becomes
very convenient to correlate network activity with Linux kernel application
traces.
Use the same implementation as ktime_get_boot_fast_ns() does by reading the
monotonic time and adding the TAI offset. The same limitations as for the fast
boot implementation apply. The TAI offset may change at run time e.g., by
setting the time or using adjtimex() with an offset. However, these kind of
offset changes are rare events. Nevertheless, the user has to be aware and deal
with it in post processing.
An alternative approach would be to use the same implementation as
ktime_get_real_fast_ns() does. However, this requires to add an additional u64
member to the tk_read_base struct. This struct together with a seqcount is
designed to fit into a single cache line on 64 bit architectures. Adding a new
member would violate this constraint.
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20220414091805.89667-2-kurt@linutronix.de
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Waiman Long
Baoquan He
Rafael Aquini
Audra Mitchell
Rado Vrbovsky
Jerry Snitselaar
Lucas Zampieri
Donald Dutile
Ivan Vecera
Mark Langsdorf
Chris von Recklinghausen
Nico Pache
Jaroslav Kysela
David Arcari
Jan Stancek
Artem Savkov