The patch titled Subject: mm: add missing static initializer for init_mm::mm_cid.lock has been added to the -mm mm-new branch. Its filename is mm-add-missing-static-initializer-for-init_mm-mm_cidlock.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

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------------------------------------------------------ From: Mathieu Desnoyers mathieu.desnoyers@efficios.com Subject: mm: add missing static initializer for init_mm::mm_cid.lock Date: Sun, 21 Dec 2025 18:29:22 -0500

Patch series "MM_CID and HPCC mm_struct static init fixes".

Mark Brown reported a regression [1] on linux next due to the hierarchical percpu counters (HPCC). You mentioned they were only in mm-new (and therefore not pulled into -next) [2], but it looks like they got more exposure that we expected. :)

This bug hunting got me to fix static initialization issues in both MM_CID (for upstream) and HPCC (mm-new). Mark tested my series and confirmed that it fixes his issues.

This patch (of 5):

Initialize the mm_cid.lock struct member of init_mm.

Link: https://lkml.kernel.org/r/20251221232926.450602-2-mathieu.desnoyers@efficios... Fixes: 8cea569ca785 ("sched/mmcid: Use proper data structures") Signed-off-by: Mathieu Desnoyers mathieu.desnoyers@efficios.com Cc: Thomas Gleixner tglx@linutronix.de Cc: Mark Brown broonie@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/init-mm.c | 3 +++ 1 file changed, 3 insertions(+)

--- a/mm/init-mm.c~mm-add-missing-static-initializer-for-init_mm-mm_cidlock +++ a/mm/init-mm.c @@ -44,6 +44,9 @@ struct mm_struct init_mm = { .mm_lock_seq = SEQCNT_ZERO(init_mm.mm_lock_seq), #endif .user_ns = &init_user_ns, +#ifdef CONFIG_SCHED_MM_CID + .mm_cid.lock = __RAW_SPIN_LOCK_UNLOCKED(init_mm.mm_cid.lock), +#endif .cpu_bitmap = CPU_BITS_NONE, INIT_MM_CONTEXT(init_mm) }; _

Patches currently in -mm which might be from mathieu.desnoyers@efficios.com are

lib-introduce-hierarchical-per-cpu-counters.patch mm-fix-oom-killer-inaccuracy-on-large-many-core-systems.patch mm-implement-precise-oom-killer-task-selection.patch mm-add-missing-static-initializer-for-init_mm-mm_cidlock.patch mm-rename-cpu_bitmap-field-to-flexible_array.patch mm-take-into-account-mm_cid-size-for-mm_struct-static-definitions.patch mm-take-into-account-hierarchical-percpu-tree-items-for-static-mm_struct-definitions.patch tsacct-skip-all-kernel-threads.patch