kernel/git/stable/linux.git/tools/testing/selftests/cgroup, branch master

Merge tag 'mm-stable-2026-08-26-15-22' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2026-08-27T16:17:06+00:00

Pull more MM updates from Andrew Morton: - "mm/rmap: index MAP_PRIVATE file-backed folios by anonymous pgoff" (Lorenzo Stoakes) Index MAP_PRIVATE file-backed folios by their anonymous page offset to resolve confusion around reverse mapping for zeroed and CoW'd file-backed memory. Use this new VMA anonymous page offset tracking to eliminate index conflicts and lay the foundation for scalable CoW performance improvements. - "promote mapped executable folios after first usage for MGLRU" (Baolin Wang) Make MGLRU's protection of mapped executable file folios more reliable. Follow the classical LRU's logic, promoting mapped executable file folios after their first usage to give executable code a better chance to stay in memory and improve workload performance. - "mm: vmscan: fix node reclaim ignoring swappiness parameter" (Ridong Chen) Fix per-node proactive reclaim interface's ignoring the swappiness parameter when CONFIG_MEMCG is disabled by consolidating sc_swappiness() into a single function that checks proactive_swappiness regardless of kernel configuration. - "mm/vmscan: reduce lru_lock contention via vmstat-derived scan-balance cost" (Usama Arif) Reduce lru_lock contention in the reclaim path by deriving scan-balance costs from vmstat counters rather than lock-acquired producer updates. Read and decay these cost signals on the reclaim side under a dedicated per-lruvec lock, reducing total LRU lock wait time by over 60% without impacting scan throughput. - "zram: fix zram issues reported by sashiko" (Sergey Senozhatsky) Fix two low-risk zram bugs which Sashiko spotted in drive-by review. - "Honor XA_FLAGS_ACCOUNT in xas_split_alloc() and charge to folio's memcg" (Zi Yan) Fix xas_split_alloc() by enabling target folio memcg charging during splits and adding the missing __GFP_ACCOUNT flag for proper XArray node memory accounting. - "selftests/mm: use pattern matching in .gitignore" (Pratyush Mallick) Replace hardcoded binary names in selftests/mm/.gitignore with a generic pattern-matching rule to automatically ignore generated test files and avoid manual updates when adding new tests. - "mm/page_ext: remove pgdat_page_ext_init()" (Sang-Heon Jeon) Make the incompatibility between FLATMEM and NUMA explicit in mm/Kconfig and remove the unused pgdat_page_ext_init() function. - "zram: fix zstd error paths and add parameter validation" (Haoqin Huang) Clean up zram compression backends by removing redundant error cleanup, adding parameter and dictionary validation, auto-prefixing algorithm error logs, and resetting parameters prior to reinitialization. - "zram: fix stale scan bounds after reinitialization" (Longlong Xia) Prevent out-of-bounds slot accesses during concurrent zram resets by moving table scan bound calculations under dev_lock in writeback_store() and read_block_state(). - "add anon mTHP collapse test cases" (Baolin Wang) Extend selftests helper functions to support arbitrary page orders and add new test cases and options for mTHP collapse in khugepaged. - "selftests/mm: Handle unsupported and transient test conditions" (Muhammad Usama Anjum) Update MM selftests to report a SKIP status instead of a failure when required kernel or filesystem features are unsupported, while adding retry logic for transient page migration errors. - "mm/zswap: Fixes and improves the zswap shrink" (Hao Jia) Fix the missing zswap global shrinker when CONFIG_MEMCG is disabled and extend shrink_memcg() to support batch writeback for improved writeback efficiency. - "alloc_tag: introduce IOCTL-based filtering for MAP" (Suren Baghdasaryan) Introduce an IOCTL-based binary interface for memory allocation profiling that enables kernel-side filtering before per-CPU counter aggregation. This eliminates the text-parsing overhead of /proc/allocinfo and provides up to a 20x speedup by transferring only filtered allocation data to userspace. - "better block swap batching and a different take on swap_ops v5" (Christoph Hellwig) Refactor block swap I/O to use swap_iocb for batching instead of single-bio requests and rebase the swap_ops interface, achieving faster swap throughput during kernel builds. - "mm: kmemleak: reduce transient false positives by confirming leaks" (Catalin Marinas) Reduce false-positive kmemleak reports by combining two kmemleak enhancements that add a second confirmation scan and a configurable minimum unreferenced scan count module parameter. - "mm: kmemleak: default min_unref_scans to 2 for verbose kernels" (Breno Leitao) Auto-scanning kernels can generate false-positive memory leak reports on single scans, so this patch defaults min_unref_scans to 2 when CONFIG_DEBUG_KMEMLEAK_VERBOSE is enabled to require a second confirming scan. - "swap_ops updates" (Christoph Hellwig) Batching I/O for synchronous swap devices causes performance regressions and filesystem-based swap suffers from double-indirection overhead. This series resolves both issues by reintroducing per-folio writes for synchronous swap and allowing filesystems to directly export their own swap_ops. - "mm/khugepaged: several cleanups" (Nico Pache) khugepaged accumulated redundant state-checking patterns and outdated comments following mTHP integration. Introduce dedicated helpers for PTE validation and event counting while refreshing the internal documentation. - "maple_tree: lock checking and clean ups" (Liam Howlett) Syzbot reports incorrectly blame memory management exit paths for locking bugs, maple tree erase operations risk allocation failures without gfp flags and internal documentation lacks clarity. Improve lock error detection, update docs, fix race and allocation edge cases and optimize erase allocations using a fallback to GFP_KERNEL | GFP_NOFAIL. * tag 'mm-stable-2026-08-26-15-22' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (172 commits) selftests/proc: make proc-maps-race work with READ_IMPLIES_EXEC memcg: move LRU size accounting on reparenting instead of copying it mm/vmscan: fix comment logic in balance_pgdat maple_tree: add helper mas_make_walkable() maple_tree: avoid extra gap calculation maple_tree: fix argument name in header maple_tree: change two GFP flags in tests maple_tree: document erase and allocations better maple_tree: avoid mas_erase() and mtree_erase() failures maple_tree: document that erase may use GFP_KERNEL for allocations maple_tree: catch race in mas_alloc_cyclic() maple_tree: add bulk parent set helper maple_tree: micro optimisation of mas_wr_store_type() maple_tree: optimise mas_wr_node_store() when not in rcu mode maple_tree: use prefetched value in mas_wr_store_type() maple_tree: clarify comments on mas_nomem() maple_tree: drop MAPLE_ALLOC_SLOTS maple_tree: drop dead code from mas_extend_spanning_null() maple_tree: documentation fix maple_tree: add write lock checking with lockdep sequence numbers ...

selftests/cgroup: test_zswap: skip test_no_kmem_bypass if debugfs is unavailable

2026-08-25T01:43:21+00:00

test_no_kmem_bypass() needs to read /sys/kernel/debug/zswap/stored_pages via get_zswap_stored_pages() to verify that compressed pages are charged to the memcg. When running in an environment where debugfs is not mounted or CONFIG_DEBUG_FS is disabled, get_zswap_stored_pages() fails, causing the loop to terminate early and report a false negative (KSFT_FAIL). Selftests should not fail if debugfs is unavailable, and it should print a message when it is skipped. While I'm here, also add a warning message if the test is being skipped due to totalram size and make the check for totalram more readable. [akpm@linux-foundation.org: clarify debugfs-unavailable error message] Link: https://lore.kernel.org/20260812050848.848882-1-wfelipe@google.com Link: https://lore.kernel.org/20260811051434.3805648-1-wfelipe@google.com Signed-off-by: Wilson Felipe Pereira Reviewed-by: Anshuman Khandual Reviewed-by: SJ Park Cc: Chengming Zhou Cc: Johannes Weiner Cc: Michal Koutný Cc: Nhat Pham Cc: Shuah Khan Cc: Tejun Heo Signed-off-by: Andrew Morton

selftests/cgroup: Remove redundant chown in test_cgcore_lesser_ns_open

2026-08-14T18:32:58+00:00

test_cgcore_lesser_ns_open runs as root throughout and never changes its euid, so chowning the two cgroup.procs files to a non-root uid has no effect on the test. The ENOENT the test expects comes from the cgroup namespace delegation check in cgroup_procs_write_permission(): the source and destination cgroups must both be descendants of the namespace root captured at open time. That check does not depend on file ownership. In addition, the permission check only examines the common ancestor's cgroup.procs file (the test root here), which the chown calls do not touch. Remove the redundant chown calls and the now unused test_euid and cg_test_a_procs variables. Signed-off-by: Shaojie Sun Reviewed-by: Tao Cui Signed-off-by: Tejun Heo

selftests/cgroup: Preserve CPU hotplug write errors

2026-08-13T17:07:34+00:00

The cpuset partition root state selftest checks several CPU hotplug transitions. If writing to a CPU online file fails, the helper still runs pause afterwards and returns the status of pause instead of the failed write. This hides the real hotplug failure and can make later checks run against expectations for a transition that never happened. Move the write before the bookkeeping and return when it fails, so callers can observe the hotplug error and the test does not record a CPU as offline unless the offline operation actually succeeded. Also change the O* command handler in set_ctrl_state() to use "eval $COMM $REDIRECT" like all other handlers. The previous version set COMM but still called write_cpu_online directly, bypassing the redirect that captures stderr for error reporting. Changes since v1: - Use eval $COMM $REDIRECT in the O* handler instead of calling write_cpu_online directly (Waiman Long) Fixes: a8c52eba880a ("kselftest/cgroup: Add cpuset v2 partition root state test") Signed-off-by: Rui Qi Signed-off-by: Tejun Heo

cgroup/cpuset: Add test for partition root invalidation returning wrong CPUs

2026-08-12T01:59:35+00:00

Add a test case to REMOTE_TEST_MATRIX covering the bug fixed by commit 345f40166694 ("cgroup/cpuset: Return only actually allocated CPUs during partition invalidation"). The test verifies that when a sibling partition root changes its cpuset.cpus to overlap with another partition root, only actually allocated CPUs (effective_xcpus) are returned to the parent, not all CPUs in cpus_allowed. Signed-off-by: Shaojie Sun Reviewed-by: Waiman Long Signed-off-by: Tejun Heo

selftests/cgroup: Avoid awk -e in cpuset tests

2026-08-10T19:28:03+00:00

The cpuset selftests use awk -e to parse cgroup mount points. This works with gawk, but mawk rejects the option. In test_cpuset_prs.sh, this leaves CGROUP2 empty and causes the test to skip as if cgroup v2 were not mounted. The same non-portable invocation exists in the cpuset v1 hotplug test. The scripts only need to pass a single awk program. Use the standard awk invocation without -e so mount point detection works with awk implementations that do not support the gawk extension. Fixes: a8c52eba880a ("kselftest/cgroup: Add cpuset v2 partition root state test") Fixes: 812c5945bdb8 ("cgroup/cpuset: Add test_cpuset_v1_hp.sh") Signed-off-by: Rui Qi Acked-by: Waiman Long Reviewed-by: Ridong Chen Signed-off-by: Tejun Heo

selftests/cgroup: add user_usec sanity check in test_cpucg_nice

2026-08-02T19:50:55+00:00

In test_cpucg_nice, after the child process exits, user_usec is read from cpu.stat but the value is not checked. Add a sanity check to ensure user_usec > 0, analogous to test_cpucg_stats(), so that the test fails early if CPU usage wasn't properly accounted. Signed-off-by: Shaojie Sun Reviewed-by: Michal Koutný Acked-by: Tao Cui Signed-off-by: Tejun Heo

selftests/cgroup: Fix minor defects in test_cpuset

2026-07-17T22:12:44+00:00

With commit 98149f542530 ("selftests/cgroup: Add test for cpuset affinity on controller disable"), sashiko [1] reported 3 different issues with the new test_cpuset_affinity_on_controller_disable() test. 1) `cpu_set_equal` iterates over mask bytes instead of bits, ignoring CPUs >= 8. 2) Thread synchronization logic allows the main thread to read uninitialized stack memory, causing test flakiness. 3) Test fails instead of skipping gracefully on uniprocessor systems or when CPU 1 is unavailable. Fix the reported issues by: 1) Iterates over the bit size of the mask. 2) Test the new ready flag for each thread to end the wait on the conditional variable and eliminate the now unneeded AFFINITY_THREAD_A_READY and AFFINITY_THREADS_READY test phases. 3) Return KSFT_SKIP on "cpuset.cpus" setting failure. [1] https://sashiko.dev/#/patchset/20260712235510.373125-1-longman%40redhat.com Fixes: 98149f542530 ("selftests/cgroup: Add test for cpuset affinity on controller disable") Signed-off-by: Waiman Long Signed-off-by: Tejun Heo

selftests/cgroup: Remove redundant cg_enter_current() call in test_core

2026-07-17T17:05:40+00:00

The test_cgcore_no_internal_process_constraint_on_threads test has two back-to-back cg_enter_current(root) calls in its cleanup path. A single cg_enter_current() call atomically migrates the entire thread group to the target cgroup even for multi-threaded processes, and this test creates no extra threads or child processes that would require a second migration attempt. The second call is a harmless no-op once the process is already in the root cgroup, but it is redundant and inconsistent with the cleanup logic used in all other cgroup core selftest cases. Remove the duplicate call to clean up the code. No functional change is intended. Signed-off-by: Jian Guo Acked-by: Michal Koutný Tested-by: Tao Cui Signed-off-by: Tejun Heo

selftests/cgroup: Add test for cpuset affinity on controller disable

2026-07-16T19:38:22+00:00

Add a new selftest that exposes a bug in cpuset_attach() where thread CPU affinity is not properly updated when the cpuset controller is disabled in a threaded cgroup hierarchy. The test creates a threaded cgroup hierarchy with two child cgroups (A and B) having different cpuset.cpus constraints: - Parent: cpuset.cpus=0-1 - Child A: cpuset.cpus=0-1 - Child B: cpuset.cpus=1 (restricted to CPU 1 only) A multithreaded process is created with threads placed in different cgroups. When the cpuset controller is disabled on the parent, thread affinities should be updated to match the parent's cpuset. Expected behavior: - thread_a affinity: {0-1} before and after (unchanged) - thread_b affinity: {1} before, {0-1} after (expanded) Current buggy behavior: - thread_b affinity remains {1} after controller disable Assisted-by: Claude:claude-sonnet-4-5 Signed-off-by: Michal Koutný Acked-by: Waiman Long Signed-off-by: Tejun Heo