[PATCH v2 3/5] memcg: use high_work for kernel threads
flat view
WARM2d
REVIEWED: 1 (1M)
From: Shakeel Butt <shakeel.butt@linux.dev>
Date: 2026-10-30 20:54:44
Also in:
linux-mm, lkml
Subsystem:
control group - memory resource controller (memcg), memory management, the rest · Maintainers:
Johannes Weiner, Michal Hocko, Roman Gushchin, Shakeel Butt, Andrew Morton, Linus Torvalds
Status: Reviewed.
Revision v2 (2 revisions archived); 1 review trailer.
Revisions (2)
- v1
- v2 current [diff against previous]
Kernel threads never return to userspace, so deferred memory.high reclaim does not run. Reclaim and throttling during a charge can also delay work they do for other tasks. Treat kernel threads like interrupts. Queue high_work for the first cgroup over memory.high and skip reclaim and throttling in the charging thread. User workers created by create_io_thread() and vhost_task_create() keep their current behavior. Vhost kernel threads use the new path, even when they borrow the owner's mm. The worker requests a fixed batch of pages each time. A fast allocator can keep usage well above memory.high. Kernel threads also skip memory.swap.high throttling and its high-event reporting. The memory.max and memory.swap.max checks stay the same. Suggested-by: Tejun Heo <tj@kernel.org> Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> Acked-by: Michal Hocko <mhocko@suse.com> --- mm/memcontrol.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index af95a4574a0f..42bdaaacafb7 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c@@ -2708,6 +2708,7 @@ static void memcg_enforce_high(struct mem_cgroup *memcg, unsigned int nr_pages, gfp_t gfp_mask) { bool allow_spinning = gfpflags_allow_spinning(gfp_mask); + bool use_worker = !in_task() || (current->flags & PF_KTHREAD); /* * If the hierarchy is above the normal consumption range, schedule
@@ -2726,8 +2727,12 @@ static void memcg_enforce_high(struct mem_cgroup *memcg, unsigned int nr_pages, swap_high = page_counter_read(&memcg->swap) > READ_ONCE(memcg->swap.high); - /* Don't bother a random interrupted task */ - if (!in_task()) { + /* + * Don't make an unrelated interrupted task handle this charge. + * Kernel threads may be working for other tasks, so let a worker + * reclaim instead. + */ + if (use_worker) { if (mem_high) { if (allow_spinning) schedule_work(&memcg->high_work);
@@ -2754,6 +2759,10 @@ static void memcg_enforce_high(struct mem_cgroup *memcg, unsigned int nr_pages, } } while ((memcg = parent_mem_cgroup(memcg))); + /* Interrupts and kernel threads stop here. */ + if (use_worker) + return; + /* * Reclaim is set up above to be called from the userland * return path. But also attempt synchronous reclaim to avoid
--
2.53.0-Meta