linux/lib, branch v6.2-rc4

lockref: stop doing cpu_relax in the cmpxchg loop

2023-01-13T20:35:38Z

On the x86-64 architecture even a failing cmpxchg grants exclusive access to the cacheline, making it preferable to retry the failed op immediately instead of stalling with the pause instruction. To illustrate the impact, below are benchmark results obtained by running various will-it-scale tests on top of the 6.2-rc3 kernel and Cascade Lake (2 sockets * 24 cores * 2 threads) CPU. All results in ops/s. Note there is some variance in re-runs, but the code is consistently faster when contention is present. open3 ("Same file open/close"): proc stock no-pause 1 805603 814942 (+%1) 2 1054980 1054781 (-0%) 8 1544802 1822858 (+18%) 24 1191064 2199665 (+84%) 48 851582 1469860 (+72%) 96 609481 1427170 (+134%) fstat2 ("Same file fstat"): proc stock no-pause 1 3013872 3047636 (+1%) 2 4284687 4400421 (+2%) 8 3257721 5530156 (+69%) 24 2239819 5466127 (+144%) 48 1701072 5256609 (+209%) 96 1269157 6649326 (+423%) Additionally, a kernel with a private patch to help access() scalability: access2 ("Same file access"): proc stock patched patched +nopause 24 2378041 2005501 5370335 (-15% / +125%) That is, fixing the problems in access itself *reduces* scalability after the cacheline ping-pong only happens in lockref with the pause instruction. Note that fstat and access benchmarks are not currently integrated into will-it-scale, but interested parties can find them in pull requests to said project. Code at hand has a rather tortured history. First modification showed up in commit d472d9d98b46 ("lockref: Relax in cmpxchg loop"), written with Itanium in mind. Later it got patched up to use an arch-dependent macro to stop doing it on s390 where it caused a significant regression. Said macro had undergone revisions and was ultimately eliminated later, going back to cpu_relax. While I intended to only remove cpu_relax for x86-64, I got the following comment from Linus: I would actually prefer just removing it entirely and see if somebody else hollers. You have the numbers to prove it hurts on real hardware, and I don't think we have any numbers to the contrary. So I think it's better to trust the numbers and remove it as a failure, than say "let's just remove it on x86-64 and leave everybody else with the potentially broken code" Additionally, Will Deacon (maintainer of the arm64 port, one of the architectures previously benchmarked): So, from the arm64 side of the fence, I'm perfectly happy just removing the cpu_relax() calls from lockref. As such, come back full circle in history and whack it altogether. Signed-off-by: Mateusz Guzik Link: https://lore.kernel.org/all/CAGudoHHx0Nqg6DE70zAVA75eV-HXfWyhVMWZ-aSeOofkA_=WdA@mail.gmail.com/ Acked-by: Tony Luck # ia64 Acked-by: Nicholas Piggin # powerpc Acked-by: Will Deacon # arm64 Acked-by: Peter Zijlstra Signed-off-by: Linus Torvalds

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma

2023-01-07T18:06:47Z

Pull rdma fixes from Jason Gunthorpe: "Most noticeable is that Yishai found a big data corruption regression due to a change in the scatterlist: - Do not wrongly combine non-contiguous pages in scatterlist - Fix compilation warnings on gcc 13 - Oops when using some mlx5 stats - Bad enforcement of atomic responder resources in mlx5" * tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma: lib/scatterlist: Fix to merge contiguous pages into the last SG properly RDMA/mlx5: Fix validation of max_rd_atomic caps for DC RDMA/mlx5: Fix mlx5_ib_get_hw_stats when used for device RDMA/srp: Move large values to a new enum for gcc13

lib/scatterlist: Fix to merge contiguous pages into the last SG properly

2023-01-05T20:01:05Z

When sg_alloc_append_table_from_pages() calls to pages_are_mergeable() in its 'sgt_append->prv' flow to check whether it can merge contiguous pages into the last SG, it passes the page arguments in the wrong order. The first parameter should be the next candidate page to be merged to the last page and not the opposite. The current code leads to a corrupted SG which resulted in OOPs and unexpected errors when non-contiguous pages are merged wrongly. Fix to pass the page parameters in the right order. Fixes: 1567b49d1a40 ("lib/scatterlist: add check when merging zone device pages") Link: https://lore.kernel.org/r/20230105112339.107969-1-yishaih@nvidia.com Signed-off-by: Yishai Hadas Reviewed-by: Jason Gunthorpe Reviewed-by: Logan Gunthorpe Signed-off-by: Jason Gunthorpe

kunit: alloc_string_stream_fragment error handling bug fix

2022-12-26T23:01:36Z

When it fails to allocate fragment, it does not free and return error. And check the pointer inappropriately. Fixed merge conflicts with commit 618887768bb7 ("kunit: update NULL vs IS_ERR() tests") Shuah Khan Signed-off-by: YoungJun.park Reviewed-by: David Gow Signed-off-by: Shuah Khan

test_maple_tree: add test for mas_spanning_rebalance() on insufficient data

2022-12-21T22:31:52Z

Add a test to the maple tree test suite for the spanning rebalance insufficient node issue does not go undetected again. Link: https://lkml.kernel.org/r/20221219161922.2708732-3-Liam.Howlett@oracle.com Fixes: 54a611b60590 ("Maple Tree: add new data structure") Signed-off-by: Liam R. Howlett Cc: Andrei Vagin Cc: Mike Rapoport Cc: Muhammad Usama Anjum Cc: Signed-off-by: Andrew Morton

maple_tree: fix mas_spanning_rebalance() on insufficient data

2022-12-21T22:31:52Z

Mike Rapoport contacted me off-list with a regression in running criu. Periodic tests fail with an RCU stall during execution. Although rare, it is possible to hit this with other uses so this patch should be backported to fix the regression. This patchset adds the fix and a test case to the maple tree test suite. This patch (of 2): An insufficient node was causing an out-of-bounds access on the node in mas_leaf_max_gap(). The cause was the faulty detection of the new node being a root node when overwriting many entries at the end of the tree. Fix the detection of a new root and ensure there is sufficient data prior to entering the spanning rebalance loop. Link: https://lkml.kernel.org/r/20221219161922.2708732-1-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20221219161922.2708732-2-Liam.Howlett@oracle.com Fixes: 54a611b60590 ("Maple Tree: add new data structure") Signed-off-by: Liam R. Howlett Reported-by: Mike Rapoport Tested-by: Mike Rapoport Cc: Andrei Vagin Cc: Mike Rapoport Cc: Muhammad Usama Anjum Cc: Signed-off-by: Andrew Morton

Merge tag 'spdx-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx

2022-12-20T14:53:16Z

Pull SPDX/License additions from Greg KH: "Here are two small updates for LICENSES and some kernel files that add the Copyleft-next license and use it in a SPDX tag as a dual-license for some kernel files. These have been discussed thoroughly in public on the linux-spdx mailing list, and have the needed acks on them, as well as having been in linux-next with no reported issues for quite some time" * tag 'spdx-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx: testing: use the copyleft-next-0.3.1 SPDX tag LICENSES: Add the copyleft-next-0.3.1 license

Merge tag 'asm-generic-6.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

2022-12-20T14:32:11Z

Pull asm-generic updates from Arnd Bergmann: "There are only three fairly simple patches. The #include change to linux/swab.h addresses a userspace build issue, and the change to the mmio tracing logic helps provide more useful traces" * tag 'asm-generic-6.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic: uapi: Add missing _UAPI prefix to include guard asm-generic/io: Add _RET_IP_ to MMIO trace for more accurate debug info include/uapi/linux/swab: Fix potentially missing __always_inline

Merge tag 'kbuild-v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2022-12-19T18:33:32Z

Pull Kbuild updates from Masahiro Yamada: - Support zstd-compressed debug info - Allow W=1 builds to detect objects shared among multiple modules - Add srcrpm-pkg target to generate a source RPM package - Make the -s option detection work for future GNU Make versions - Add -Werror to KBUILD_CPPFLAGS when CONFIG_WERROR=y - Allow W=1 builds to detect -Wundef warnings in any preprocessed files - Raise the minimum supported version of binutils to 2.25 - Use $(intcmp ...) to compare integers if GNU Make >= 4.4 is used - Use $(file ...) to read a file if GNU Make >= 4.2 is used - Print error if GNU Make older than 3.82 is used - Allow modpost to detect section mismatches with Clang LTO - Include vmlinuz.efi into kernel tarballs for arm64 CONFIG_EFI_ZBOOT=y * tag 'kbuild-v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (29 commits) buildtar: fix tarballs with EFI_ZBOOT enabled modpost: Include '.text.*' in TEXT_SECTIONS padata: Mark padata_work_init() as __ref kbuild: ensure Make >= 3.82 is used kbuild: refactor the prerequisites of the modpost rule kbuild: change module.order to list *.o instead of *.ko kbuild: use .NOTINTERMEDIATE for future GNU Make versions kconfig: refactor Makefile to reduce process forks kbuild: add read-file macro kbuild: do not sort after reading modules.order kbuild: add test-{ge,gt,le,lt} macros Documentation: raise minimum supported version of binutils to 2.25 kbuild: add -Wundef to KBUILD_CPPFLAGS for W=1 builds kbuild: move -Werror from KBUILD_CFLAGS to KBUILD_CPPFLAGS kbuild: Port silent mode detection to future gnu make. init/version.c: remove #include firmware_loader: remove #include modpost: Mark uuid_le type to be suitable only for MEI kbuild: add ability to make source rpm buildable using koji kbuild: warn objects shared among multiple modules ...

Merge tag 'zstd-linus-v6.2' of https://github.com/terrelln/linux

2022-12-19T18:26:03Z

Pull zstd updates from Nick Terrell: "Update the kernel to upstream zstd v1.5.2 [0]. Specifically to the tag v1.5.2-kernel [1] which includes several cherrypicked fixes for the kernel on top of v1.5.2. Excepting the MAINTAINERS change, all the changes in this can be generated by: git clone https://github.com/facebook/zstd cd zstd/contrib/linux-kernel git checkout v1.5.2-kernel LINUX=/path/to/linux/repo make import Additionally, this includes several minor typo fixes, which have all been fixed upstream so they are maintained on the next import" Link: https://github.com/facebook/zstd/releases/tag/v1.5.2 [0] Link: https://github.com/facebook/zstd/tree/v1.5.2-kernel [1] Link: https://lore.kernel.org/lkml/20221024202606.404049-1-nickrterrell@gmail.com/ Link: https://github.com/torvalds/linux/commit/637a642f5ca5e850186bb64ac75ebb0f124b458d * tag 'zstd-linus-v6.2' of https://github.com/terrelln/linux: zstd: import usptream v1.5.2 zstd: Move zstd-common module exports to zstd_common_module.c lib: zstd: Fix comment typo lib: zstd: fix repeated words in comments MAINTAINERS: git://github -> https://github.com for terrelln lib: zstd: clean up double word in comment.