The patch titled
Subject: memcg/hugetlb: introduce memcg_accounts_hugetlb
has been added to the -mm mm-unstable branch. Its filename is
memcg-hugetlb-introduce-memcg_accounts_hugetlb.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/memcg-hugetlb-introduce-memcg_accounts_hugetlb.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Joshua Hahn <joshua.hahnjy@xxxxxxxxx>
Subject: memcg/hugetlb: introduce memcg_accounts_hugetlb
Date: Wed, 11 Dec 2024 12:39:49 -0800
Patch series "memcg/hugetlb: Rework memcg hugetlb charging", v3.
This series cleans up memcg's hugetlb charging logic by deprecating the
current memcg hugetlb try-charge + {commit, cancel} logic present in
alloc_hugetlb_folio. A single function mem_cgroup_charge_hugetlb takes
its place instead. This makes the code more maintainable by simplifying
the error path and reduces memcg's footprint in hugetlb logic.
This patch introduces a few changes in the hugetlb folio allocation
error path:
(a) Instead of having multiple return points, we consolidate them to
two: one for reaching the memcg limit or running out of memory
(-ENOMEM) and one for hugetlb allocation fails / limit being
reached (-ENOSPC).
(b) Previously, the memcg limit was checked before the folio is acquired,
meaning the hugeTLB folio isn't acquired if the limit is reached.
This patch performs the charging after the folio is reached, meaning
if memcg's limit is reached, the acquired folio is freed right away.
This patch builds on two earlier patch series: [2] which adds memcg
hugeTLB counters, and [3] which deprecates charge moving and removes the
last references to mem_cgroup_cancel_charge. The request for this cleanup
can be found in [2].
[1] https://lore.kernel.org/all/20231006184629.155543-1-nphamcs@xxxxxxxxx/
[2] https://lore.kernel.org/all/20241101204402.1885383-1-joshua.hahnjy@xxxxxxxxx/
[3] https://lore.kernel.org/linux-mm/20241025012304.2473312-1-shakeel.butt@xxxxxxxxx/
This patch (of 3):
This patch isolates the check for whether memcg accounts hugetlb. This
condition can only be true if the memcg mount option
memory_hugetlb_accounting is on, which includes hugetlb usage in
memory.current.
Link: https://lkml.kernel.org/r/20241211203951.764733-1-joshua.hahnjy@xxxxxxxxx
Link: https://lkml.kernel.org/r/20241211203951.764733-2-joshua.hahnjy@xxxxxxxxx
Signed-off-by: Joshua Hahn <joshua.hahnjy@xxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Cc: Shakeel Butt <shakeel.butt@xxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
--- a/mm/memcontrol.c~memcg-hugetlb-introduce-memcg_accounts_hugetlb
+++ a/mm/memcontrol.c
@@ -1448,6 +1448,18 @@ unsigned long memcg_page_state_local_out
memcg_page_state_output_unit(item);
}
+#ifdef CONFIG_HUGETLB_PAGE
+static bool memcg_accounts_hugetlb(void)
+{
+ return cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_HUGETLB_ACCOUNTING;
+}
+#else /* CONFIG_HUGETLB_PAGE */
+static bool memcg_accounts_hugetlb(void)
+{
+ return false;
+}
+#endif /* CONFIG_HUGETLB_PAGE */
+
static void memcg_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)
{
int i;
@@ -1469,7 +1481,7 @@ static void memcg_stat_format(struct mem
#ifdef CONFIG_HUGETLB_PAGE
if (unlikely(memory_stats[i].idx == NR_HUGETLB) &&
- !(cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_HUGETLB_ACCOUNTING))
+ !memcg_accounts_hugetlb())
continue;
#endif
size = memcg_page_state_output(memcg, memory_stats[i].idx);
@@ -4540,8 +4552,7 @@ int mem_cgroup_hugetlb_try_charge(struct
* but do not attempt to commit charge later (or cancel on error) either.
*/
if (mem_cgroup_disabled() || !memcg ||
- !cgroup_subsys_on_dfl(memory_cgrp_subsys) ||
- !(cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_HUGETLB_ACCOUNTING))
+ !cgroup_subsys_on_dfl(memory_cgrp_subsys) || !memcg_accounts_hugetlb())
return -EOPNOTSUPP;
if (try_charge(memcg, gfp, nr_pages))
_
Patches currently in -mm which might be from joshua.hahnjy@xxxxxxxxx are
memcg-hugetlb-introduce-memcg_accounts_hugetlb.patch
memcg-hugetlb-introduce-mem_cgroup_charge_hugetlb.patch
memcg-hugetlb-remove-memcg-hugetlb-try-commit-cancel-protocol.patch
