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[PATCH v4 0/3] VMM can handle guest SEA via KVM_EXIT_ARM_SEA

by Jiaqi Yan

Problem ======= When host APEI is unable to claim a synchronous external abort (SEA) during guest abort, today KVM directly injects an asynchronous SError into the VCPU then resumes it. The injected SError usually results in unpleasant guest kernel panic. One of the major situation of guest SEA is when VCPU consumes recoverable uncorrected memory error (UER), which is not uncommon at all in modern datacenter servers with large amounts of physical memory. Although SError and guest panic is sufficient to stop the propagation of corrupted memory, there is room to recover from an UER in a more graceful manner. Proposed Solution ================= The idea is, we can replay the SEA to the faulting VCPU. If the memory error consumption or the fault that cause SEA is not from guest kernel, the blast radius can be limited to the poison-consuming guest process, while the VM can keep running. In addition, instead of doing under the hood without involving userspace, there are benefits to redirect the SEA to VMM: - VM customers care about the disruptions caused by memory errors, and VMM usually has the responsibility to start the process of notifying the customers of memory error events in their VMs. For example some cloud provider emits a critical log in their observability UI [1], and provides a playbook for customers on how to mitigate disruptions to their workloads. - VMM can protect future memory error consumption by unmapping the poisoned pages from stage-2 page table with KVM userfault [2], or by splitting the memslot that contains the poisoned pages. - VMM can keep track of SEA events in the VM. When VMM thinks the status on the host or the VM is bad enough, e.g. number of distinct SEAs exceeds a threshold, it can restart the VM on another healthy host. - Behavior parity with x86 architecture. When machine check exception (MCE) is caused by VCPU, kernel or KVM signals userspace SIGBUS to let VMM either recover from the MCE, or terminate itself with VM. The prior RFC proposes to implement SIGBUS on arm64 as well, but Marc preferred KVM exit over signal [3]. However, implementation aside, returning SEA to VMM is on par with returning MCE to VMM. Once SEA is redirected to VMM, among other actions, VMM is encouraged to inject external aborts into the faulting VCPU. New UAPIs ========= This patchset introduces following userspace-visible changes to empower VMM to control what happens for SEA on guest memory: - KVM_CAP_ARM_SEA_TO_USER. While taking SEA, if userspace has enabled this new capability at VM creation, and the SEA is not owned by kernel allocated memory, instead of injecting SError, return KVM_EXIT_ARM_SEA to userspace. - KVM_EXIT_ARM_SEA. This is the VM exit reason VMM gets. The details about the SEA is provided in arm_sea as much as possible, including sanitized ESR value at EL2, faulting guest virtual and physical addresses if available. * From v3 [4] - Rebased on commit 3a8660878839 ("Linux 6.18-rc1"). - In selftest, print a message if GVA or GPA expects to be valid. * From v2 [5]: - Rebased on "[PATCH] KVM: arm64: nv: Handle SEAs due to VNCR redirection" [6] and kvmarm/next commit 7b8346bd9fce6 ("KVM: arm64: Don't attempt vLPI mappings when vPE allocation is disabled") - Took the host_owns_sea implementation from Oliver [7, 8]. - Excluded the guest SEA injection patches. - Updated selftest. * From v1 [9]: - Rebased on commit 4d62121ce9b5 ("KVM: arm64: vgic-debug: Avoid dereferencing NULL ITE pointer"). - Sanitize ESR_EL2 before reporting it to userspace. - Do not do KVM_EXIT_ARM_SEA when SEA is caused by memory allocated to stage-2 translation table. [1] https://cloud.google.com/solutions/sap/docs/manage-host-errors [2] https://lore.kernel.org/kvm/20250109204929.1106563-1-jthoughton@google.com [3] https://lore.kernel.org/kvm/86pljbqqh0.wl-maz@kernel.org [4] https://lore.kernel.org/kvmarm/20250731205844.1346839-1-jiaqiyan@google.com [5] https://lore.kernel.org/kvm/20250604050902.3944054-1-jiaqiyan@google.com [6] https://lore.kernel.org/kvmarm/20250729182342.3281742-1-oliver.upton@linux.… [7] https://lore.kernel.org/kvm/aHFohmTb9qR_JG1E@linux.dev [8] https://lore.kernel.org/kvm/aHK-DPufhLy5Dtuk@linux.dev [9] https://lore.kernel.org/kvm/20250505161412.1926643-1-jiaqiyan@google.com Jiaqi Yan (3): KVM: arm64: VM exit to userspace to handle SEA KVM: selftests: Test for KVM_EXIT_ARM_SEA Documentation: kvm: new UAPI for handling SEA Documentation/virt/kvm/api.rst | 61 ++++ arch/arm64/include/asm/kvm_host.h | 2 + arch/arm64/kvm/arm.c | 5 + arch/arm64/kvm/mmu.c | 68 +++- include/uapi/linux/kvm.h | 10 + tools/arch/arm64/include/asm/esr.h | 2 + tools/testing/selftests/kvm/Makefile.kvm | 1 + .../testing/selftests/kvm/arm64/sea_to_user.c | 331 ++++++++++++++++++ tools/testing/selftests/kvm/lib/kvm_util.c | 1 + 9 files changed, 480 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/kvm/arm64/sea_to_user.c -- 2.51.0.760.g7b8bcc2412-goog

3 weeks

8
18
0 0

[PATCH v9 0/9] liveupdate: Rework KHO for in-kernel users

by Pasha Tatashin

Changelog: v9: Added review-bys and addressed comments from Mike Rapoport and Pratyush Yadav. Dropped patch that moves abort/finalize to public header per Mike's request. Added patch from Zhu Yanjun to output errors by name. This series appliyes against akpm's mm-unstable branch. This series refactors the KHO framework to better support in-kernel users like the upcoming LUO. The current design, which relies on a notifier chain and debugfs for control, is too restrictive for direct programmatic use. The core of this rework is the removal of the notifier chain in favor of a direct registration API. This decouples clients from the shutdown-time finalization sequence, allowing them to manage their preserved state more flexibly and at any time. In support of this new model, this series also: - Makes the debugfs interface optional. - Introduces APIs to unpreserve memory and fixes a bug in the abort path where client state was being incorrectly discarded. Note that this is an interim step, as a more comprehensive fix is planned as part of the stateless KHO work [1]. - Moves all KHO code into a new kernel/liveupdate/ directory to consolidate live update components. [1] https://lore.kernel.org/all/20251020100306.2709352-1-jasonmiu@google.com Mike Rapoport (Microsoft) (1): kho: drop notifiers Pasha Tatashin (7): kho: make debugfs interface optional kho: add interfaces to unpreserve folios, page ranges, and vmalloc memblock: Unpreserve memory in case of error test_kho: Unpreserve memory in case of error kho: don't unpreserve memory during abort liveupdate: kho: move to kernel/liveupdate MAINTAINERS: update KHO maintainers Zhu Yanjun (1): liveupdate: kho: Use %pe format specifier for error pointer printing Documentation/core-api/kho/concepts.rst | 2 +- MAINTAINERS | 4 +- include/linux/kexec_handover.h | 46 +- init/Kconfig | 2 + kernel/Kconfig.kexec | 24 - kernel/Makefile | 3 +- kernel/kexec_handover_internal.h | 16 - kernel/liveupdate/Kconfig | 39 ++ kernel/liveupdate/Makefile | 5 + kernel/{ => liveupdate}/kexec_handover.c | 532 +++++++----------- .../{ => liveupdate}/kexec_handover_debug.c | 0 kernel/liveupdate/kexec_handover_debugfs.c | 221 ++++++++ kernel/liveupdate/kexec_handover_internal.h | 56 ++ lib/test_kho.c | 128 +++-- mm/memblock.c | 93 +-- tools/testing/selftests/kho/vmtest.sh | 1 + 16 files changed, 690 insertions(+), 482 deletions(-) delete mode 100644 kernel/kexec_handover_internal.h create mode 100644 kernel/liveupdate/Kconfig create mode 100644 kernel/liveupdate/Makefile rename kernel/{ => liveupdate}/kexec_handover.c (80%) rename kernel/{ => liveupdate}/kexec_handover_debug.c (100%) create mode 100644 kernel/liveupdate/kexec_handover_debugfs.c create mode 100644 kernel/liveupdate/kexec_handover_internal.h base-commit: 9ef7b034116354ee75502d1849280a4d2ff98a7c -- 2.51.1.930.gacf6e81ea2-goog

3 weeks

7
40
0 0

[GIT PULL] kselftest fixes update for Linux 6.18-rc6

by Shuah Khan

Hi Linus, Please pull this kselftest fixes update for Linux 6.18-rc6 Fixes event-filter-function.tc tracing test failure caused when a first run to sample events triggers kmem_cache_free which interferes with the rest of the test. Fix this calling sample_events twice to eliminate the kmem_cache_free related noise from the sampling. diff is attached. thanks, -- Shuah ---------------------------------------------------------------- The following changes since commit 920aa3a7705a061cb3004572d8b7932b54463dbf: selftests: cachestat: Fix warning on declaration under label (2025-10-22 09:23:18 -0600) are available in the Git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest tags/linux_kselftest-fixes-6.18-rc6 for you to fetch changes up to dd4adb986a86727ed8f56c48b6d0695f1e211e65: selftests/tracing: Run sample events to clear page cache events (2025-11-10 18:00:07 -0700) ---------------------------------------------------------------- linux_kselftest-fixes-6.18-rc6 Fixes event-filter-function.tc tracing test failure caused when a first run to sample events triggers kmem_cache_free which interferes with the rest of the test. Fix this calling sample_events twice to eliminate the kmem_cache_free related noise from the sampling. ---------------------------------------------------------------- Steven Rostedt (1): selftests/tracing: Run sample events to clear page cache events tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc | 4 ++++ 1 file changed, 4 insertions(+) ----------------------------------------------------------------

3 weeks

2
1
0 0

[PATCH v2] selftests/mm/uffd: remove static address usage in shmem_allocate_area()

by Mehdi Ben Hadj Khelifa

The current shmem_allocate_area() implementation uses a hardcoded virtual base address (BASE_PMD_ADDR) as a hint for mmap() when creating shmem-backed test areas. This approach is fragile and may fail on systems with ASLR or different virtual memory layouts, where the chosen address is unavailable. Replace the static base address with a dynamically reserved address range obtained via mmap(NULL, ..., PROT_NONE). The memfd-backed areas and their alias are then mapped into that reserved region using MAP_FIXED, preserving the original layout and aliasing semantics while avoiding collisions with unrelated mappings. This change improves robustness and portability of the test suite without altering its behavior or coverage. Suggested-by: Mike Rapoport <rppt(a)kernel.org> Signed-off-by: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa(a)gmail.com> --- Testing(Retested): A diff between running the mm selftests on 6.18-rc5 from before and after the change show no regression on x86_64 architecture with 32GB DDR5 RAM. ChangeLog: Changes from v1: -Implemented Mike's suggestions to make cleanup code more clear. Link:https://lore.kernel.org/all/20251111205739.420009-1-mehdi.benhadjkheli… tools/testing/selftests/mm/uffd-common.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) diff --git a/tools/testing/selftests/mm/uffd-common.c b/tools/testing/selftests/mm/uffd-common.c index 994fe8c03923..edd02328f77b 100644 --- a/tools/testing/selftests/mm/uffd-common.c +++ b/tools/testing/selftests/mm/uffd-common.c @@ -10,7 +10,6 @@ uffd_test_ops_t *uffd_test_ops; uffd_test_case_ops_t *uffd_test_case_ops; -#define BASE_PMD_ADDR ((void *)(1UL << 30)) /* pthread_mutex_t starts at page offset 0 */ pthread_mutex_t *area_mutex(char *area, unsigned long nr, uffd_global_test_opts_t *gopts) @@ -142,30 +141,37 @@ static int shmem_allocate_area(uffd_global_test_opts_t *gopts, void **alloc_area unsigned long offset = is_src ? 0 : bytes; char *p = NULL, *p_alias = NULL; int mem_fd = uffd_mem_fd_create(bytes * 2, false); + size_t region_size = bytes * 2 + hpage_size; - /* TODO: clean this up. Use a static addr is ugly */ - p = BASE_PMD_ADDR; - if (!is_src) - /* src map + alias + interleaved hpages */ - p += 2 * (bytes + hpage_size); + void *reserve = mmap(NULL, region_size, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, + -1, 0); + if (reserve == MAP_FAILED) { + close(mem_fd); + return -errno; + } + + p = reserve; p_alias = p; p_alias += bytes; p_alias += hpage_size; /* Prevent src/dst VMA merge */ - *alloc_area = mmap(p, bytes, PROT_READ | PROT_WRITE, MAP_SHARED, + *alloc_area = mmap(p, bytes, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_SHARED, mem_fd, offset); if (*alloc_area == MAP_FAILED) { *alloc_area = NULL; + munmap(reserve, region_size); + close(mem_fd); return -errno; } if (*alloc_area != p) err("mmap of memfd failed at %p", p); - area_alias = mmap(p_alias, bytes, PROT_READ | PROT_WRITE, MAP_SHARED, + area_alias = mmap(p_alias, bytes, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_SHARED, mem_fd, offset); if (area_alias == MAP_FAILED) { - munmap(*alloc_area, bytes); *alloc_area = NULL; + munmap(reserve, region_size); + close(mem_fd); return -errno; } if (area_alias != p_alias) -- 2.51.2

3 weeks

2
1
0 0

[PATCH] selftests/mm/uffd: remove static address usage in shmem_allocate_area()

by Mehdi Ben Hadj Khelifa

The current shmem_allocate_area() implementation uses a hardcoded virtual base address(BASE_PMD_ADDR) as a hint for mmap() when creating shmem-backed test areas. This approach is fragile and may fail on systems with ASLR or different virtual memory layouts, where the chosen address is unavailable. Replace the static base address with a dynamically reserved address range obtained via mmap(NULL, ..., PROT_NONE). The memfd-backed areas and their alias are then mapped into that reserved region using MAP_FIXED, preserving the original layout and aliasing semantics while avoiding collisions with unrelated mappings. This change improves robustness and portability of the test suite without altering its behavior or coverage. Signed-off-by: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa(a)gmail.com> --- Testing: A diff between running the mm selftests on 6.18-rc5 from before and after the change show no regression on x86_64 architecture with 32GB DDR5 RAM. tools/testing/selftests/mm/uffd-common.c | 25 +++++++++++++++--------- 1 file changed, 16 insertions(+), 9 deletions(-) diff --git a/tools/testing/selftests/mm/uffd-common.c b/tools/testing/selftests/mm/uffd-common.c index 994fe8c03923..492b21c960bb 100644 --- a/tools/testing/selftests/mm/uffd-common.c +++ b/tools/testing/selftests/mm/uffd-common.c @@ -6,11 +6,11 @@ */ #include "uffd-common.h" +#include "asm-generic/mman-common.h" uffd_test_ops_t *uffd_test_ops; uffd_test_case_ops_t *uffd_test_case_ops; -#define BASE_PMD_ADDR ((void *)(1UL << 30)) /* pthread_mutex_t starts at page offset 0 */ pthread_mutex_t *area_mutex(char *area, unsigned long nr, uffd_global_test_opts_t *gopts) @@ -142,30 +142,37 @@ static int shmem_allocate_area(uffd_global_test_opts_t *gopts, void **alloc_area unsigned long offset = is_src ? 0 : bytes; char *p = NULL, *p_alias = NULL; int mem_fd = uffd_mem_fd_create(bytes * 2, false); + size_t region_size = bytes * 2 + hpage_size; - /* TODO: clean this up. Use a static addr is ugly */ - p = BASE_PMD_ADDR; - if (!is_src) - /* src map + alias + interleaved hpages */ - p += 2 * (bytes + hpage_size); + void *reserve = mmap(NULL, region_size, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, + -1, 0); + if (reserve == MAP_FAILED) { + close(mem_fd); + return -errno; + } + + p = (char *)reserve; p_alias = p; p_alias += bytes; p_alias += hpage_size; /* Prevent src/dst VMA merge */ - *alloc_area = mmap(p, bytes, PROT_READ | PROT_WRITE, MAP_SHARED, + *alloc_area = mmap(p, bytes, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_SHARED, mem_fd, offset); if (*alloc_area == MAP_FAILED) { + munmap(reserve, region_size); *alloc_area = NULL; + close(mem_fd); return -errno; } if (*alloc_area != p) err("mmap of memfd failed at %p", p); - area_alias = mmap(p_alias, bytes, PROT_READ | PROT_WRITE, MAP_SHARED, + area_alias = mmap(p_alias, bytes, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_SHARED, mem_fd, offset); if (area_alias == MAP_FAILED) { - munmap(*alloc_area, bytes); + munmap(reserve, region_size); *alloc_area = NULL; + close(mem_fd); return -errno; } if (area_alias != p_alias) -- 2.51.2

3 weeks

2
2
0 0

[PATCH v3 0/2] libbpf: fix BTF dedup to support recursive typedef

by Paul Houssel

Pahole fails to encode BTF for some Go projects (e.g. Kubernetes and Podman) due to recursive type definitions that create reference loops not representable in C. These recursive typedefs trigger a failure in the BTF deduplication algorithm. This patch extends btf_dedup_struct_types() to properly handle potential recursion for BTF_KIND_TYPEDEF, similar to how recursion is already handled for BTF_KIND_STRUCT. This allows pahole to successfully generate BTF for Go binaries using recursive types without impacting existing C-based workflows. Changes in v3: 1. Patch 1: Adjusted the comment of btf_dedup_ref_type() to refer to typedef as well. 2. Patch 2: Update of the "dedup: recursive typedef" test to include a duplicated version of the types to make sure deduplication still happens in this case. Changes in v2: 1. Patch 1: Refactored code to prevent copying existing logic. Instead of adding a new function we modify the existing btf_dedup_struct_type() function to handle the BTF_KIND_TYPEDEF case. Calls to btf_hash_struct() and btf_shallow_equal_struct() are replaced with calls to functions that select btf_hash_struct() / btf_hash_typedef() based on the type. 2. Patch 2: Added tests v2: https://lore.kernel.org/lkml/cover.1762956564.git.paul.houssel@orange.com/ v1: https://lore.kernel.org/lkml/20251107153408.159342-1-paulhoussel2@gmail.com/ Paul Houssel (2): libbpf: fix BTF dedup to support recursive typedef definitions selftests/bpf: add BTF dedup tests for recursive typedef definitions tools/lib/bpf/btf.c | 73 +++++++++++++++----- tools/testing/selftests/bpf/prog_tests/btf.c | 65 +++++++++++++++++ 2 files changed, 121 insertions(+), 17 deletions(-) -- 2.51.0

3 weeks

2
3
0 0

[PATCH v2 0/4] KVM ARM64 pre_fault_memory

by Jack Thomson

From: Jack Thomson <jackabt(a)amazon.com> This patch series adds ARM64 support for the KVM_PRE_FAULT_MEMORY feature, which was previously only available on x86 [1]. This allows us to reduce the number of stage-2 faults during execution. This is of benefit in post-copy migration scenarios, particularly in memory intensive applications, where we are experiencing high latencies due to the stage-2 faults. Patch Overview: - The first patch adds support for the KVM_PRE_FAULT_MEMORY ioctl on arm64. - The second patch fixes an issue with unaligned mmap allocations in the selftests. - The third patch updates the pre_fault_memory_test to support arm64. - The last patch extends the pre_fault_memory_test to cover different vm memory backings. === Changes Since v1 [2] === Addressing feedback from Oliver: - No pre-fault flag is passed to user_mem_abort() or gmem_abort() now aborts are synthesized. - Remove retry loop from kvm_arch_vcpu_pre_fault_memory() [1]: https://lore.kernel.org/kvm/20240710174031.312055-1-pbonzini@redhat.com [2]: https://lore.kernel.org/all/20250911134648.58945-1-jackabt.amazon@gmail.com Jack Thomson (4): KVM: arm64: Add pre_fault_memory implementation KVM: selftests: Fix unaligned mmap allocations KVM: selftests: Enable pre_fault_memory_test for arm64 KVM: selftests: Add option for different backing in pre-fault tests Documentation/virt/kvm/api.rst | 3 +- arch/arm64/kvm/Kconfig | 1 + arch/arm64/kvm/arm.c | 1 + arch/arm64/kvm/mmu.c | 73 +++++++++++- tools/testing/selftests/kvm/Makefile.kvm | 1 + tools/testing/selftests/kvm/lib/kvm_util.c | 12 +- .../selftests/kvm/pre_fault_memory_test.c | 110 +++++++++++++----- 7 files changed, 163 insertions(+), 38 deletions(-) base-commit: 42188667be387867d2bf763d028654cbad046f7b -- 2.43.0

3 weeks

4
11
0 0

[PATCH v5] selftests: af_unix: Add tests for ECONNRESET and EOF semantics

by Sunday Adelodun

Add selftests to verify and document Linux’s intended behaviour for UNIX domain sockets (SOCK_STREAM and SOCK_DGRAM) when a peer closes. The tests verify that: 1. SOCK_STREAM returns EOF when the peer closes normally. 2. SOCK_STREAM returns ECONNRESET if the peer closes with unread data. 3. SOCK_SEQPACKET returns EOF when the peer closes normally. 4. SOCK_SEQPACKET returns ECONNRESET if the peer closes with unread data. 5. SOCK_DGRAM does not return ECONNRESET when the peer closes. This follows up on review feedback suggesting a selftest to clarify Linux’s semantics. Suggested-by: Kuniyuki Iwashima <kuniyu(a)google.com> Signed-off-by: Sunday Adelodun <adelodunolaoluwa(a)yahoo.com> --- Changelog: changes made in v4 to v5: 1. Moved the send() call before the socket type check in Test 2 to ensure the unread data behavior is tested for SOCK_DGRAM as well. 2. Removed the misleading commend about accept() for clarity. 3. Applied indentation fixes for style consistency (alignment with open parenthesis). 4. Minor comment and formatting cleanups for clarity and adherence to kernel coding style. tools/testing/selftests/net/.gitignore | 1 + tools/testing/selftests/net/af_unix/Makefile | 1 + .../selftests/net/af_unix/unix_connreset.c | 178 ++++++++++++++++++ 3 files changed, 180 insertions(+) create mode 100644 tools/testing/selftests/net/af_unix/unix_connreset.c diff --git a/tools/testing/selftests/net/.gitignore b/tools/testing/selftests/net/.gitignore index 439101b518ee..e89a60581a13 100644 --- a/tools/testing/selftests/net/.gitignore +++ b/tools/testing/selftests/net/.gitignore @@ -65,3 +65,4 @@ udpgso udpgso_bench_rx udpgso_bench_tx unix_connect +unix_connreset diff --git a/tools/testing/selftests/net/af_unix/Makefile b/tools/testing/selftests/net/af_unix/Makefile index de805cbbdf69..5826a8372451 100644 --- a/tools/testing/selftests/net/af_unix/Makefile +++ b/tools/testing/selftests/net/af_unix/Makefile @@ -7,6 +7,7 @@ TEST_GEN_PROGS := \ scm_pidfd \ scm_rights \ unix_connect \ + unix_connreset \ # end of TEST_GEN_PROGS include ../../lib.mk diff --git a/tools/testing/selftests/net/af_unix/unix_connreset.c b/tools/testing/selftests/net/af_unix/unix_connreset.c new file mode 100644 index 000000000000..9cb0f48597eb --- /dev/null +++ b/tools/testing/selftests/net/af_unix/unix_connreset.c @@ -0,0 +1,178 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Selftest for AF_UNIX socket close and ECONNRESET behaviour. + * + * This test verifies: + * 1. SOCK_STREAM returns EOF when the peer closes normally. + * 2. SOCK_STREAM returns ECONNRESET if peer closes with unread data. + * 3. SOCK_SEQPACKET returns EOF when the peer closes normally. + * 4. SOCK_SEQPACKET returns ECONNRESET if the peer closes with unread data. + * 5. SOCK_DGRAM does not return ECONNRESET when the peer closes. + * + * These tests document the intended Linux behaviour. + * + */ + +#define _GNU_SOURCE +#include <stdlib.h> +#include <string.h> +#include <fcntl.h> +#include <unistd.h> +#include <errno.h> +#include <sys/socket.h> +#include <sys/un.h> +#include "../../kselftest_harness.h" + +#define SOCK_PATH "/tmp/af_unix_connreset.sock" + +static void remove_socket_file(void) +{ + unlink(SOCK_PATH); +} + +FIXTURE(unix_sock) +{ + int server; + int client; + int child; +}; + +FIXTURE_VARIANT(unix_sock) +{ + int socket_type; + const char *name; +}; + +FIXTURE_VARIANT_ADD(unix_sock, stream) { + .socket_type = SOCK_STREAM, + .name = "SOCK_STREAM", +}; + +FIXTURE_VARIANT_ADD(unix_sock, dgram) { + .socket_type = SOCK_DGRAM, + .name = "SOCK_DGRAM", +}; + +FIXTURE_VARIANT_ADD(unix_sock, seqpacket) { + .socket_type = SOCK_SEQPACKET, + .name = "SOCK_SEQPACKET", +}; + +FIXTURE_SETUP(unix_sock) +{ + struct sockaddr_un addr = {}; + int err; + + addr.sun_family = AF_UNIX; + strcpy(addr.sun_path, SOCK_PATH); + remove_socket_file(); + + self->server = socket(AF_UNIX, variant->socket_type, 0); + ASSERT_LT(-1, self->server); + + err = bind(self->server, (struct sockaddr *)&addr, sizeof(addr)); + ASSERT_EQ(0, err); + + if (variant->socket_type == SOCK_STREAM || + variant->socket_type == SOCK_SEQPACKET) { + err = listen(self->server, 1); + ASSERT_EQ(0, err); + } + + self->client = socket(AF_UNIX, variant->socket_type | SOCK_NONBLOCK, 0); + ASSERT_LT(-1, self->client); + + err = connect(self->client, (struct sockaddr *)&addr, sizeof(addr)); + ASSERT_EQ(0, err); +} + +FIXTURE_TEARDOWN(unix_sock) +{ + if ((variant->socket_type == SOCK_STREAM || + variant->socket_type == SOCK_SEQPACKET) & self->child > 0) + close(self->child); + + close(self->client); + close(self->server); + remove_socket_file(); +} + +/* Test 1: peer closes normally */ +TEST_F(unix_sock, eof) +{ + char buf[16] = {}; + ssize_t n; + + if (variant->socket_type == SOCK_STREAM || + variant->socket_type == SOCK_SEQPACKET) { + self->child = accept(self->server, NULL, NULL); + ASSERT_LT(-1, self->child); + + close(self->child); + } else { + close(self->server); + } + + n = recv(self->client, buf, sizeof(buf), 0); + + if (variant->socket_type == SOCK_STREAM || + variant->socket_type == SOCK_SEQPACKET) { + ASSERT_EQ(0, n); + } else { + ASSERT_EQ(-1, n); + ASSERT_EQ(EAGAIN, errno); + } +} + +/* Test 2: peer closes with unread data */ +TEST_F(unix_sock, reset_unread_behavior) +{ + char buf[16] = {}; + ssize_t n; + + /* Send data that will remain unread */ + send(self->client, "hello", 5, 0); + + if (variant->socket_type == SOCK_DGRAM) { + /* No real connection, just close the server */ + close(self->server); + } else { + /* Accept client connection */ + self->child = accept(self->server, NULL, NULL); + ASSERT_LT(-1, self->child); + + /* Peer closes before client reads */ + close(self->child); + } + + n = recv(self->client, buf, sizeof(buf), 0); + ASSERT_EQ(-1, n); + + if (variant->socket_type == SOCK_STREAM || + variant->socket_type == SOCK_SEQPACKET) { + ASSERT_EQ(ECONNRESET, errno); + } else { + ASSERT_EQ(EAGAIN, errno); + } +} + +/* Test 3: closing unaccepted (embryo) server socket should reset client. */ +TEST_F(unix_sock, reset_closed_embryo) +{ + char buf[16] = {}; + ssize_t n; + + if (variant->socket_type == SOCK_DGRAM) + SKIP(return, "This test only applies to SOCK_STREAM and SOCK_SEQPACKET"); + + /* Close server without accept()ing */ + close(self->server); + + n = recv(self->client, buf, sizeof(buf), 0); + + ASSERT_EQ(-1, n); + ASSERT_EQ(ECONNRESET, errno); +} + +TEST_HARNESS_MAIN + -- 2.43.0

3 weeks

2
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[PATCH v4] selftests: af_unix: Add tests for ECONNRESET and EOF semantics

by Sunday Adelodun

Add selftests to verify and document Linux’s intended behaviour for UNIX domain sockets (SOCK_STREAM and SOCK_DGRAM) when a peer closes. The tests verify that: 1. SOCK_STREAM returns EOF when the peer closes normally. 2. SOCK_STREAM returns ECONNRESET if the peer closes with unread data. 3. SOCK_SEQPACKET returns EOF when the peer closes normally. 4. SOCK_SEQPACKET returns ECONNRESET if the peer closes with unread data. 5. SOCK_DGRAM does not return ECONNRESET when the peer closes. This follows up on review feedback suggesting a selftest to clarify Linux’s semantics. Suggested-by: Kuniyuki Iwashima <kuniyu(a)google.com> Signed-off-by: Sunday Adelodun <adelodunolaoluwa(a)yahoo.com> --- tools/testing/selftests/net/.gitignore | 1 + tools/testing/selftests/net/af_unix/Makefile | 1 + .../selftests/net/af_unix/unix_connreset.c | 178 ++++++++++++++++++ 3 files changed, 180 insertions(+) create mode 100644 tools/testing/selftests/net/af_unix/unix_connreset.c diff --git a/tools/testing/selftests/net/.gitignore b/tools/testing/selftests/net/.gitignore index 439101b518ee..e89a60581a13 100644 --- a/tools/testing/selftests/net/.gitignore +++ b/tools/testing/selftests/net/.gitignore @@ -65,3 +65,4 @@ udpgso udpgso_bench_rx udpgso_bench_tx unix_connect +unix_connreset diff --git a/tools/testing/selftests/net/af_unix/Makefile b/tools/testing/selftests/net/af_unix/Makefile index de805cbbdf69..5826a8372451 100644 --- a/tools/testing/selftests/net/af_unix/Makefile +++ b/tools/testing/selftests/net/af_unix/Makefile @@ -7,6 +7,7 @@ TEST_GEN_PROGS := \ scm_pidfd \ scm_rights \ unix_connect \ + unix_connreset \ # end of TEST_GEN_PROGS include ../../lib.mk diff --git a/tools/testing/selftests/net/af_unix/unix_connreset.c b/tools/testing/selftests/net/af_unix/unix_connreset.c new file mode 100644 index 000000000000..9413f8a0814f --- /dev/null +++ b/tools/testing/selftests/net/af_unix/unix_connreset.c @@ -0,0 +1,178 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Selftest for AF_UNIX socket close and ECONNRESET behaviour. + * + * This test verifies: + * 1. SOCK_STREAM returns EOF when the peer closes normally. + * 2. SOCK_STREAM returns ECONNRESET if peer closes with unread data. + * 3. SOCK_SEQPACKET returns EOF when the peer closes normally. + * 4. SOCK_SEQPACKET returns ECONNRESET if the peer closes with unread data. + * 5. SOCK_DGRAM does not return ECONNRESET when the peer closes. + * + * These tests document the intended Linux behaviour. + * + */ + +#define _GNU_SOURCE +#include <stdlib.h> +#include <string.h> +#include <fcntl.h> +#include <unistd.h> +#include <errno.h> +#include <sys/socket.h> +#include <sys/un.h> +#include "../../kselftest_harness.h" + +#define SOCK_PATH "/tmp/af_unix_connreset.sock" + +static void remove_socket_file(void) +{ + unlink(SOCK_PATH); +} + +FIXTURE(unix_sock) +{ + int server; + int client; + int child; +}; + +FIXTURE_VARIANT(unix_sock) +{ + int socket_type; + const char *name; +}; + +FIXTURE_VARIANT_ADD(unix_sock, stream) { + .socket_type = SOCK_STREAM, + .name = "SOCK_STREAM", +}; + +FIXTURE_VARIANT_ADD(unix_sock, dgram) { + .socket_type = SOCK_DGRAM, + .name = "SOCK_DGRAM", +}; + +FIXTURE_VARIANT_ADD(unix_sock, seqpacket) { + .socket_type = SOCK_SEQPACKET, + .name = "SOCK_SEQPACKET", +}; + +FIXTURE_SETUP(unix_sock) +{ + struct sockaddr_un addr = {}; + int err; + + addr.sun_family = AF_UNIX; + strcpy(addr.sun_path, SOCK_PATH); + remove_socket_file(); + + self->server = socket(AF_UNIX, variant->socket_type, 0); + ASSERT_LT(-1, self->server); + + err = bind(self->server, (struct sockaddr *)&addr, sizeof(addr)); + ASSERT_EQ(0, err); + + if (variant->socket_type == SOCK_STREAM || + variant->socket_type == SOCK_SEQPACKET) { + err = listen(self->server, 1); + ASSERT_EQ(0, err); + } + + self->client = socket(AF_UNIX, variant->socket_type | SOCK_NONBLOCK, 0); + ASSERT_LT(-1, self->client); + + err = connect(self->client, (struct sockaddr *)&addr, sizeof(addr)); + ASSERT_EQ(0, err); +} + +FIXTURE_TEARDOWN(unix_sock) +{ + if ((variant->socket_type == SOCK_STREAM || + variant->socket_type == SOCK_SEQPACKET) & self->child > 0) + close(self->child); + + close(self->client); + close(self->server); + remove_socket_file(); +} + +/* Test 1: peer closes normally */ +TEST_F(unix_sock, eof) +{ + char buf[16] = {}; + ssize_t n; + + if (variant->socket_type == SOCK_STREAM || + variant->socket_type == SOCK_SEQPACKET) { + self->child = accept(self->server, NULL, NULL); + ASSERT_LT(-1, self->child); + + close(self->child); + } else { + close(self->server); + } + + n = recv(self->client, buf, sizeof(buf), 0); + + if (variant->socket_type == SOCK_STREAM || + variant->socket_type == SOCK_SEQPACKET) { + ASSERT_EQ(0, n); + } else { + ASSERT_EQ(-1, n); + ASSERT_EQ(EAGAIN, errno); + } +} + +/* Test 2: peer closes with unread data */ +TEST_F(unix_sock, reset_unread_behavior) +{ + char buf[16] = {}; + ssize_t n; + + if (variant->socket_type == SOCK_DGRAM) { + /* No real connection, just close the server */ + close(self->server); + } else { + /* Establish full connection first */ + self->child = accept(self->server, NULL, NULL); + ASSERT_LT(-1, self->child); + + /* Send data that will remain unread */ + send(self->client, "hello", 5, 0); + + /* Peer closes before client reads */ + close(self->child); + } + + n = recv(self->client, buf, sizeof(buf), 0); + ASSERT_EQ(-1, n); + + if (variant->socket_type == SOCK_STREAM || + variant->socket_type == SOCK_SEQPACKET) { + ASSERT_EQ(ECONNRESET, errno); + } else { + ASSERT_EQ(EAGAIN, errno); + } +} + +/* Test 3: closing unaccepted (embryo) server socket should reset client. */ +TEST_F(unix_sock, reset_closed_embryo) +{ + char buf[16] = {}; + ssize_t n; + + if (variant->socket_type == SOCK_DGRAM) + SKIP(return, "This test only applies to SOCK_STREAM and SOCK_SEQPACKET"); + + /* Close server without accept()ing */ + close(self->server); + + n = recv(self->client, buf, sizeof(buf), 0); + + ASSERT_EQ(-1, n); + ASSERT_EQ(ECONNRESET, errno); +} + +TEST_HARNESS_MAIN + -- 2.43.0

3 weeks

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6
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[PATCH v1] cpuset: Avoid unnecessary partition invalidation

by Sun Shaojie

Currently, when a non-exclusive cpuset's "cpuset.cpus" overlaps with a partitioned sibling, the sibling's partition state becomes invalid. However, this invalidation is often unnecessary. This can be observed in specific configuration sequences: Case 1: Partition created first, then non-exclusive cpuset overlaps #1> mkdir -p /sys/fs/cgroup/A1 #2> echo "0-1" > /sys/fs/cgroup/A1/cpuset.cpus #3> echo "root" > /sys/fs/cgroup/A1/cpuset.cpus.partition #4> mkdir -p /sys/fs/cgroup/B1 #5> echo "0-3" > /sys/fs/cgroup/B1/cpuset.cpus // A1's partition becomes "root invalid" - this is unnecessary Case 2: Non-exclusive cpuset exists first, then partition created #1> mkdir -p /sys/fs/cgroup/B1 #2> echo "0-1" > /sys/fs/cgroup/B1/cpuset.cpus #3> mkdir -p /sys/fs/cgroup/A1 #4> echo "0-1" > /sys/fs/cgroup/A1/cpuset.cpus #5> echo "root" > /sys/fs/cgroup/A1/cpuset.cpus.partition // A1's partition becomes "root invalid" - this is unnecessary In Case 1, the effective CPU mask of B1 can differ from its requested mask. B1 can use CPUs 2-3 which don't overlap with A1's exclusive CPUs (0-1), thus not violating A1's exclusivity requirement. In Case 2, B1 can inherit the effective CPUs from its parent, so there is no need to invalidate A1's partition state. This patch relaxes the overlap check to only consider conflicts between partitioned siblings, not between a partitioned cpuset and a regular non-exclusive one. Signed-off-by: Sun Shaojie <sunshaojie(a)kylinos.cn> --- kernel/cgroup/cpuset.c | 8 ++++---- tools/testing/selftests/cgroup/test_cpuset_prs.sh | 10 +++++----- 2 files changed, 9 insertions(+), 9 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 52468d2c178a..e0d27c9a101a 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -586,14 +586,14 @@ static inline bool cpusets_are_exclusive(struct cpuset *cs1, struct cpuset *cs2) * Returns: true if CPU exclusivity conflict exists, false otherwise * * Conflict detection rules: - * 1. If either cpuset is CPU exclusive, they must be mutually exclusive + * 1. If both cpusets are exclusive, they must be mutually exclusive * 2. exclusive_cpus masks cannot intersect between cpusets * 3. The allowed CPUs of one cpuset cannot be a subset of another's exclusive CPUs */ static inline bool cpus_excl_conflict(struct cpuset *cs1, struct cpuset *cs2) { - /* If either cpuset is exclusive, check if they are mutually exclusive */ - if (is_cpu_exclusive(cs1) || is_cpu_exclusive(cs2)) + /* If both cpusets are exclusive, check if they are mutually exclusive */ + if (is_cpu_exclusive(cs1) && is_cpu_exclusive(cs2)) return !cpusets_are_exclusive(cs1, cs2); /* Exclusive_cpus cannot intersect */ @@ -695,7 +695,7 @@ static int validate_change(struct cpuset *cur, struct cpuset *trial) goto out; /* - * If either I or some sibling (!= me) is exclusive, we can't + * If both I and some sibling (!= me) are exclusive, we can't * overlap. exclusive_cpus cannot overlap with each other if set. */ ret = -EINVAL; diff --git a/tools/testing/selftests/cgroup/test_cpuset_prs.sh b/tools/testing/selftests/cgroup/test_cpuset_prs.sh index a17256d9f88a..903dddfe88d7 100755 --- a/tools/testing/selftests/cgroup/test_cpuset_prs.sh +++ b/tools/testing/selftests/cgroup/test_cpuset_prs.sh @@ -269,7 +269,7 @@ TEST_MATRIX=( " C0-3:S+ C1-3:S+ C2-3 . X2-3 X3:P2 . . 0 A1:0-2|A2:3|A3:3 A1:P0|A2:P2 3" " C0-3:S+ C1-3:S+ C2-3 . X2-3 X2-3 X2-3:P2 . 0 A1:0-1|A2:1|A3:2-3 A1:P0|A3:P2 2-3" " C0-3:S+ C1-3:S+ C2-3 . X2-3 X2-3 X2-3:P2:C3 . 0 A1:0-1|A2:1|A3:2-3 A1:P0|A3:P2 2-3" - " C0-3:S+ C1-3:S+ C2-3 C2-3 . . . P2 0 A1:0-3|A2:1-3|A3:2-3|B1:2-3 A1:P0|A3:P0|B1:P-2" + " C0-3:S+ C1-3:S+ C2-3 C2-3 . . . P2 0 A1:0-1|A2:1|A3:1|B1:2-3 A1:P0|A3:P0|B1:P2 2-3" " C0-3:S+ C1-3:S+ C2-3 C4-5 . . . P2 0 B1:4-5 B1:P2 4-5" " C0-3:S+ C1-3:S+ C2-3 C4 X2-3 X2-3 X2-3:P2 P2 0 A3:2-3|B1:4 A3:P2|B1:P2 2-4" " C0-3:S+ C1-3:S+ C2-3 C4 X2-3 X2-3 X2-3:P2:C1-3 P2 0 A3:2-3|B1:4 A3:P2|B1:P2 2-4" @@ -318,7 +318,7 @@ TEST_MATRIX=( # Invalid to valid local partition direct transition tests " C1-3:S+:P2 X4:P2 . . . . . . 0 A1:1-3|XA1:1-3|A2:1-3:XA2: A1:P2|A2:P-2 1-3" " C1-3:S+:P2 X4:P2 . . . X3:P2 . . 0 A1:1-2|XA1:1-3|A2:3:XA2:3 A1:P2|A2:P2 1-3" - " C0-3:P2 . . C4-6 C0-4 . . . 0 A1:0-4|B1:4-6 A1:P-2|B1:P0" + " C0-3:P2 . . C4-6 C0-4 . . . 0 A1:0-4|B1:5-6 A1:P2|B1:P0 0-4" " C0-3:P2 . . C4-6 C0-4:C0-3 . . . 0 A1:0-3|B1:4-6 A1:P2|B1:P0 0-3" # Local partition invalidation tests @@ -388,10 +388,10 @@ TEST_MATRIX=( " C0-1:S+ C1 . C2-3 . P2 . . 0 A1:0-1|A2:1 A1:P0|A2:P-2" " C0-1:S+ C1:P2 . C2-3 P1 . . . 0 A1:0|A2:1 A1:P1|A2:P2 0-1|1" - # A non-exclusive cpuset.cpus change will invalidate partition and its siblings - " C0-1:P1 . . C2-3 C0-2 . . . 0 A1:0-2|B1:2-3 A1:P-1|B1:P0" + # A non-exclusive cpuset.cpus change will not invalidate partition and its siblings + " C0-1:P1 . . C2-3 C0-2 . . . 0 A1:0-2|B1:3 A1:P1|B1:P0" " C0-1:P1 . . P1:C2-3 C0-2 . . . 0 A1:0-2|B1:2-3 A1:P-1|B1:P-1" - " C0-1 . . P1:C2-3 C0-2 . . . 0 A1:0-2|B1:2-3 A1:P0|B1:P-1" + " C0-1 . . P1:C2-3 C0-2 . . . 0 A1:0-1|B1:2-3 A1:P0|B1:P1" # cpuset.cpus can overlap with sibling cpuset.cpus.exclusive but not subsumed by it " C0-3 . . C4-5 X5 . . . 0 A1:0-3|B1:4-5" -- 2.25.1

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