linux/init/Kconfig, branch v5.14

Revert "mm/slub: use stackdepot to save stack trace in objects"

2021-07-17T20:27:00Z

This reverts commit 788691464c29455346dc613a3b43c2fb9e5757a4. It's not clear why, but it causes unexplained problems in entirely unrelated xfs code. The most likely explanation is some slab corruption, possibly triggered due to CONFIG_SLUB_DEBUG_ON. See [1]. It ends up having a few other problems too, like build errors on arch/arc, and Geert reporting it using much more memory on m68k [3] (it probably does so elsewhere too, but it is probably just more noticeable on m68k). The architecture issues (both build and memory use) are likely just because this change effectively force-enabled STACKDEPOT (along with a very bad default value for the stackdepot hash size). But together with the xfs issue, this all smells like "this commit was not ready" to me. Link: https://lore.kernel.org/linux-xfs/YPE3l82acwgI2OiV@infradead.org/ [1] Link: https://lore.kernel.org/lkml/202107150600.LkGNb4Vb-lkp@intel.com/ [2] Link: https://lore.kernel.org/lkml/CAMuHMdW=eoVzM1Re5FVoEN87nKfiLmM2+Ah7eNu2KXEhCvbZyA@mail.gmail.com/ [3] Reported-by: Christoph Hellwig Reported-by: kernel test robot Reported-by: Geert Uytterhoeven Cc: Andrew Morton Cc: Vlastimil Babka Cc: Randy Dunlap Signed-off-by: Linus Torvalds

mm/slub: use stackdepot to save stack trace in objects

2021-07-08T18:48:20Z

Many stack traces are similar so there are many similar arrays. Stackdepot saves each unique stack only once. Replace field addrs in struct track with depot_stack_handle_t handle. Use stackdepot to save stack trace. The benefits are smaller memory overhead and possibility to aggregate per-cache statistics in the future using the stackdepot handle instead of matching stacks manually. [rdunlap@infradead.org: rename save_stack_trace()] Link: https://lkml.kernel.org/r/20210513051920.29320-1-rdunlap@infradead.org [vbabka@suse.cz: fix lockdep splat] Link: https://lkml.kernel.org/r/20210516195150.26740-1-vbabka@suse.czLink: https://lkml.kernel.org/r/20210414163434.4376-1-glittao@gmail.com Signed-off-by: Oliver Glitta Signed-off-by: Randy Dunlap Signed-off-by: Vlastimil Babka Reviewed-by: Vlastimil Babka Acked-by: David Rientjes Cc: Christoph Lameter Cc: Pekka Enberg Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge tag 'clang-features-v5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2021-06-30T21:33:25Z

Pull clang feature updates from Kees Cook: - Add CC_HAS_NO_PROFILE_FN_ATTR in preparation for PGO support in the face of the noinstr attribute, paving the way for PGO and fixing GCOV. (Nick Desaulniers) - x86_64 LTO coverage is expanded to 32-bit x86. (Nathan Chancellor) - Small fixes to CFI. (Mark Rutland, Nathan Chancellor) * tag 'clang-features-v5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: qemu_fw_cfg: Make fw_cfg_rev_attr a proper kobj_attribute Kconfig: Introduce ARCH_WANTS_NO_INSTR and CC_HAS_NO_PROFILE_FN_ATTR compiler_attributes.h: cleanups for GCC 4.9+ compiler_attributes.h: define __no_profile, add to noinstr x86, lto: Enable Clang LTO for 32-bit as well CFI: Move function_nocfi() into compiler.h MAINTAINERS: Add Clang CFI section

Kconfig: Introduce ARCH_WANTS_NO_INSTR and CC_HAS_NO_PROFILE_FN_ATTR

2021-06-22T18:07:18Z

We don't want compiler instrumentation to touch noinstr functions, which are annotated with the no_profile_instrument_function function attribute. Add a Kconfig test for this and make GCOV depend on it, and in the future, PGO. If an architecture is using noinstr, it should denote that via this Kconfig value. That makes Kconfigs that depend on noinstr able to express dependencies in an architecturally agnostic way. Cc: Masahiro Yamada Link: https://lore.kernel.org/lkml/YMTn9yjuemKFLbws@hirez.programming.kicks-ass.net/ Link: https://lore.kernel.org/lkml/YMcssV%2Fn5IBGv4f0@hirez.programming.kicks-ass.net/ Suggested-by: Nathan Chancellor Suggested-by: Peter Zijlstra Signed-off-by: Nick Desaulniers Reviewed-by: Peter Oberparleiter Reviewed-by: Nathan Chancellor Acked-by: Mark Rutland Acked-by: Heiko Carstens Acked-by: Peter Zijlstra (Intel) Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20210621231822.2848305-4-ndesaulniers@google.com

Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

2021-05-11T23:05:56Z

Daniel Borkmann says: ==================== pull-request: bpf 2021-05-11 The following pull-request contains BPF updates for your *net* tree. We've added 13 non-merge commits during the last 8 day(s) which contain a total of 21 files changed, 817 insertions(+), 382 deletions(-). The main changes are: 1) Fix multiple ringbuf bugs in particular to prevent writable mmap of read-only pages, from Andrii Nakryiko & Thadeu Lima de Souza Cascardo. 2) Fix verifier alu32 known-const subregister bound tracking for bitwise operations and/or/xor, from Daniel Borkmann. 3) Reject trampoline attachment for functions with variable arguments, and also add a deny list of other forbidden functions, from Jiri Olsa. 4) Fix nested bpf_bprintf_prepare() calls used by various helpers by switching to per-CPU buffers, from Florent Revest. 5) Fix kernel compilation with BTF debug info on ppc64 due to pahole missing TCP-CC functions like cubictcp_init, from Martin KaFai Lau. 6) Add a kconfig entry to provide an option to disallow unprivileged BPF by default, from Daniel Borkmann. 7) Fix libbpf compilation for older libelf when GELF_ST_VISIBILITY() macro is not available, from Arnaldo Carvalho de Melo. 8) Migrate test_tc_redirect to test_progs framework as prep work for upcoming skb_change_head() fix & selftest, from Jussi Maki. 9) Fix a libbpf segfault in add_dummy_ksym_var() if BTF is not present, from Ian Rogers. 10) Fix tx_only micro-benchmark in xdpsock BPF sample with proper frame size, from Magnus Karlsson. ==================== Signed-off-by: David S. Miller

bpf, kconfig: Add consolidated menu entry for bpf with core options

2021-05-11T20:56:16Z

Right now, all core BPF related options are scattered in different Kconfig locations mainly due to historic reasons. Moving forward, lets add a proper subsystem entry under ... General setup ---> BPF subsystem ---> ... in order to have all knobs in a single location and thus ease BPF related configuration. Networking related bits such as sockmap are out of scope for the general setup and therefore better suited to remain in net/Kconfig. Signed-off-by: Daniel Borkmann Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/f23f58765a4d59244ebd8037da7b6a6b2fb58446.1620765074.git.daniel@iogearbox.net

Merge branch 'akpm' (patches from Andrew)

2021-05-07T07:34:51Z

Merge yet more updates from Andrew Morton: "This is everything else from -mm for this merge window. 90 patches. Subsystems affected by this patch series: mm (cleanups and slub), alpha, procfs, sysctl, misc, core-kernel, bitmap, lib, compat, checkpatch, epoll, isofs, nilfs2, hpfs, exit, fork, kexec, gcov, panic, delayacct, gdb, resource, selftests, async, initramfs, ipc, drivers/char, and spelling" * emailed patches from Andrew Morton : (90 commits) mm: fix typos in comments mm: fix typos in comments treewide: remove editor modelines and cruft ipc/sem.c: spelling fix fs: fat: fix spelling typo of values kernel/sys.c: fix typo kernel/up.c: fix typo kernel/user_namespace.c: fix typos kernel/umh.c: fix some spelling mistakes include/linux/pgtable.h: few spelling fixes mm/slab.c: fix spelling mistake "disired" -> "desired" scripts/spelling.txt: add "overflw" scripts/spelling.txt: Add "diabled" typo scripts/spelling.txt: add "overlfow" arm: print alloc free paths for address in registers mm/vmalloc: remove vwrite() mm: remove xlate_dev_kmem_ptr() drivers/char: remove /dev/kmem for good mm: fix some typos and code style problems ipc/sem.c: mundane typo fixes ...

modules: add CONFIG_MODPROBE_PATH

2021-05-07T07:26:33Z

Allow the developer to specifiy the initial value of the modprobe_path[] string. This can be used to set it to the empty string initially, thus effectively disabling request_module() during early boot until userspace writes a new value via the /proc/sys/kernel/modprobe interface. [1] When building a custom kernel (often for an embedded target), it's normal to build everything into the kernel that is needed for booting, and indeed the initramfs often contains no modules at all, so every such request_module() done before userspace init has mounted the real rootfs is a waste of time. This is particularly useful when combined with the previous patch, which made the initramfs unpacking asynchronous - for that to work, it had to make any usermodehelper call wait for the unpacking to finish before attempting to invoke the userspace helper. By eliminating all such (known-to-be-futile) calls of usermodehelper, the initramfs unpacking and the {device,late}_initcalls can proceed in parallel for much longer. For a relatively slow ppc board I'm working on, the two patches combined lead to 0.2s faster boot - but more importantly, the fact that the initramfs unpacking proceeds completely in the background while devices get probed means I get to handle the gpio watchdog in time without getting reset. [1] __request_module() already has an early -ENOENT return when modprobe_path is the empty string. Link: https://lkml.kernel.org/r/20210313212528.2956377-3-linux@rasmusvillemoes.dk Signed-off-by: Rasmus Villemoes Reviewed-by: Greg Kroah-Hartman Acked-by: Jessica Yu Acked-by: Luis Chamberlain Cc: Borislav Petkov Cc: Jonathan Corbet Cc: Nick Desaulniers Cc: Takashi Iwai Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'akpm' (patches from Andrew)

2021-05-05T20:50:15Z

Merge more updates from Andrew Morton: "The remainder of the main mm/ queue. 143 patches. Subsystems affected by this patch series (all mm): pagecache, hugetlb, userfaultfd, vmscan, compaction, migration, cma, ksm, vmstat, mmap, kconfig, util, memory-hotplug, zswap, zsmalloc, highmem, cleanups, and kfence" * emailed patches from Andrew Morton : (143 commits) kfence: use power-efficient work queue to run delayed work kfence: maximize allocation wait timeout duration kfence: await for allocation using wait_event kfence: zero guard page after out-of-bounds access mm/process_vm_access.c: remove duplicate include mm/mempool: minor coding style tweaks mm/highmem.c: fix coding style issue btrfs: use memzero_page() instead of open coded kmap pattern iov_iter: lift memzero_page() to highmem.h mm/zsmalloc: use BUG_ON instead of if condition followed by BUG. mm/zswap.c: switch from strlcpy to strscpy arm64/Kconfig: introduce ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE x86/Kconfig: introduce ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE mm,memory_hotplug: add kernel boot option to enable memmap_on_memory acpi,memhotplug: enable MHP_MEMMAP_ON_MEMORY when supported mm,memory_hotplug: allocate memmap from the added memory range mm,memory_hotplug: factor out adjusting present pages into adjust_present_page_count() mm,memory_hotplug: relax fully spanned sections check drivers/base/memory: introduce memory_block_{online,offline} mm/memory_hotplug: remove broken locking of zone PCP structures during hot remove ...

userfaultfd: add minor fault registration mode

2021-05-05T18:27:22Z

Patch series "userfaultfd: add minor fault handling", v9. Overview ======== This series adds a new userfaultfd feature, UFFD_FEATURE_MINOR_HUGETLBFS. When enabled (via the UFFDIO_API ioctl), this feature means that any hugetlbfs VMAs registered with UFFDIO_REGISTER_MODE_MISSING will *also* get events for "minor" faults. By "minor" fault, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s) (shared memory). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. We also add a new ioctl to resolve such faults: UFFDIO_CONTINUE. The idea is, userspace resolves the fault by either a) doing nothing if the contents are already correct, or b) updating the underlying contents using the second, non-UFFD mapping (via memcpy/memset or similar, or something fancier like RDMA, or etc...). In either case, userspace issues UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". Use Case ======== Consider the use case of VM live migration (e.g. under QEMU/KVM): 1. While a VM is still running, we copy the contents of its memory to a target machine. The pages are populated on the target by writing to the non-UFFD mapping, using the setup described above. The VM is still running (and therefore its memory is likely changing), so this may be repeated several times, until we decide the target is "up to date enough". 2. We pause the VM on the source, and start executing on the target machine. During this gap, the VM's user(s) will *see* a pause, so it is desirable to minimize this window. 3. Between the last time any page was copied from the source to the target, and when the VM was paused, the contents of that page may have changed - and therefore the copy we have on the target machine is out of date. Although we can keep track of which pages are out of date, for VMs with large amounts of memory, it is "slow" to transfer this information to the target machine. We want to resume execution before such a transfer would complete. 4. So, the guest begins executing on the target machine. The first time it touches its memory (via the UFFD-registered mapping), userspace wants to intercept this fault. Userspace checks whether or not the page is up to date, and if not, copies the updated page from the source machine, via the non-UFFD mapping. Finally, whether a copy was performed or not, userspace issues a UFFDIO_CONTINUE ioctl to tell the kernel "I have ensured the page contents are correct, carry on setting up the mapping". We don't have to do all of the final updates on-demand. The userfaultfd manager can, in the background, also copy over updated pages once it receives the map of which pages are up-to-date or not. Interaction with Existing APIs ============================== Because this is a feature, a registered VMA could potentially receive both missing and minor faults. I spent some time thinking through how the existing API interacts with the new feature: UFFDIO_CONTINUE cannot be used to resolve non-minor faults, as it does not allocate a new page. If UFFDIO_CONTINUE is used on a non-minor fault: - For non-shared memory or shmem, -EINVAL is returned. - For hugetlb, -EFAULT is returned. UFFDIO_COPY and UFFDIO_ZEROPAGE cannot be used to resolve minor faults. Without modifications, the existing codepath assumes a new page needs to be allocated. This is okay, since userspace must have a second non-UFFD-registered mapping anyway, thus there isn't much reason to want to use these in any case (just memcpy or memset or similar). - If UFFDIO_COPY is used on a minor fault, -EEXIST is returned. - If UFFDIO_ZEROPAGE is used on a minor fault, -EEXIST is returned (or -EINVAL in the case of hugetlb, as UFFDIO_ZEROPAGE is unsupported in any case). - UFFDIO_WRITEPROTECT simply doesn't work with shared memory, and returns -ENOENT in that case (regardless of the kind of fault). Future Work =========== This series only supports hugetlbfs. I have a second series in flight to support shmem as well, extending the functionality. This series is more mature than the shmem support at this point, and the functionality works fully on hugetlbfs, so this series can be merged first and then shmem support will follow. This patch (of 6): This feature allows userspace to intercept "minor" faults. By "minor" faults, I mean the following situation: Let there exist two mappings (i.e., VMAs) to the same page(s). One of the mappings is registered with userfaultfd (in minor mode), and the other is not. Via the non-UFFD mapping, the underlying pages have already been allocated & filled with some contents. The UFFD mapping has not yet been faulted in; when it is touched for the first time, this results in what I'm calling a "minor" fault. As a concrete example, when working with hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing page. This commit adds the new registration mode, and sets the relevant flag on the VMAs being registered. In the hugetlb fault path, if we find that we have huge_pte_none(), but find_lock_page() does indeed find an existing page, then we have a "minor" fault, and if the VMA has the userfaultfd registration flag, we call into userfaultfd to handle it. This is implemented as a new registration mode, instead of an API feature. This is because the alternative implementation has significant drawbacks [1]. However, doing it this was requires we allocate a VM_* flag for the new registration mode. On 32-bit systems, there are no unused bits, so this feature is only supported on architectures with CONFIG_ARCH_USES_HIGH_VMA_FLAGS. When attempting to register a VMA in MINOR mode on 32-bit architectures, we return -EINVAL. [1] https://lore.kernel.org/patchwork/patch/1380226/ [peterx@redhat.com: fix minor fault page leak] Link: https://lkml.kernel.org/r/20210322175132.36659-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210301222728.176417-1-axelrasmussen@google.com Link: https://lkml.kernel.org/r/20210301222728.176417-2-axelrasmussen@google.com Signed-off-by: Axel Rasmussen Reviewed-by: Peter Xu Reviewed-by: Mike Kravetz Cc: Alexander Viro Cc: Alexey Dobriyan Cc: Andrea Arcangeli Cc: Anshuman Khandual Cc: Catalin Marinas Cc: Chinwen Chang Cc: Huang Ying Cc: Ingo Molnar Cc: Jann Horn Cc: Jerome Glisse Cc: Lokesh Gidra Cc: "Matthew Wilcox (Oracle)" Cc: Michael Ellerman Cc: "Michal Koutn" Cc: Michel Lespinasse Cc: Mike Rapoport Cc: Nicholas Piggin Cc: Peter Xu Cc: Shaohua Li Cc: Shawn Anastasio Cc: Steven Rostedt Cc: Steven Price Cc: Vlastimil Babka Cc: Adam Ruprecht Cc: Axel Rasmussen Cc: Cannon Matthews Cc: "Dr . David Alan Gilbert" Cc: David Rientjes Cc: Mina Almasry Cc: Oliver Upton Cc: Kirill A. Shutemov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds