The patch titled Subject: memcg: drain obj stock on cpu hotplug teardown has been added to the -mm mm-hotfixes-unstable branch. Its filename is memcg-drain-obj-stock-on-cpu-hotplug-teardown.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-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days

------------------------------------------------------ From: Shakeel Butt shakeel.butt@linux.dev Subject: memcg: drain obj stock on cpu hotplug teardown Date: Mon, 10 Mar 2025 16:09:34 -0700

Currently on cpu hotplug teardown, only memcg stock is drained but we need to drain the obj stock as well otherwise we will miss the stats accumulated on the target cpu as well as the nr_bytes cached. The stats include MEMCG_KMEM, NR_SLAB_RECLAIMABLE_B & NR_SLAB_UNRECLAIMABLE_B. In addition we are leaking reference to struct obj_cgroup object.

Link: https://lkml.kernel.org/r/20250310230934.2913113-1-shakeel.butt@linux.dev Fixes: bf4f059954dc ("mm: memcg/slab: obj_cgroup API") Signed-off-by: Shakeel Butt shakeel.butt@linux.dev Cc: Cc: Johannes Weiner hannes@cmpxchg.org Cc: Michal Hocko mhocko@kernel.org Cc: Muchun Song muchun.song@linux.dev Cc: Roman Gushchin roman.gushchin@linux.dev Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/memcontrol.c | 9 +++++++++ 1 file changed, 9 insertions(+)

--- a/mm/memcontrol.c~memcg-drain-obj-stock-on-cpu-hotplug-teardown +++ a/mm/memcontrol.c @@ -1921,9 +1921,18 @@ void drain_all_stock(struct mem_cgroup * static int memcg_hotplug_cpu_dead(unsigned int cpu) { struct memcg_stock_pcp *stock; + struct obj_cgroup *old; + unsigned long flags;

stock = &per_cpu(memcg_stock, cpu); + + /* drain_obj_stock requires stock_lock */ + local_lock_irqsave(&memcg_stock.stock_lock, flags); + old = drain_obj_stock(stock); + local_unlock_irqrestore(&memcg_stock.stock_lock, flags); + drain_stock(stock); + obj_cgroup_put(old);

return 0; } _

Patches currently in -mm which might be from shakeel.butt@linux.dev are

memcg-drain-obj-stock-on-cpu-hotplug-teardown.patch memcg-add-hierarchical-effective-limits-for-v2.patch memcg-dont-call-propagate_protected_usage-for-v1.patch page_counter-track-failcnt-only-for-legacy-cgroups.patch page_counter-reduce-struct-page_counter-size.patch memcg-bypass-root-memcg-check-for-skmem-charging.patch