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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Johannes Weiner , Yosry Ahmed , Nhat Pham , Chengming Zhou , Kairui Song , Shakeel Butt , Xunlei Pang , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260904033503.4067283-1-qinyuntan@linux.alibaba.com> <20260904033503.4067283-2-qinyuntan@linux.alibaba.com> Content-Language: en-US From: Usama Arif In-Reply-To: <20260904033503.4067283-2-qinyuntan@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: cdpbk5xxsxaoffb1keouzf64rg83sqfa X-Rspamd-Queue-Id: F1E2420004 X-HE-Tag: 1788778328-380623 X-HE-Meta: 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 ADdx3d2r 9Z8G+xXzmuwuqsNtxk1uszlRmZ89EzB3nPLC0s6Z+jD3LTi2RP3UukWSbhZYJV6SU+xXO35NRS5pjRuCmDjzfwcqd/ZQ0/Bmak9V+Wl0eaZxS0ofgIjM/VXTCSbsBQLve2tHyKY8+3q9m8bGo3XjnYxzyUHzek7qaUwguS+/axP6hHHkViiAL1lziCqKB4gsgZGjnAJRz4/gtqr5m2G0euW9jBz9ZajtjRUDift9/x00goTLQAAQAb0pZPnPcGjsVWVC/mmeUu11Q11uiLQU5n4Q9qII7tQe5v2dT6x7vN1i+ggPBidcIYz+UeTneEhazT17bpyjCX1qVDMqu5SmYhx16FhhlsxlfAqQ1sc7G/nfiy/anT1FTdQ36k428GYxooJ1FL+Q8EzaH6kmWj80eVHLXTFhatdg8GY4qcj7K24XnCir7BZvpSQxqM4je9z78fE3tAw6OE04tP2M= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 04/09/2026 04:35, Qinyun Tan wrote: > On a system booted with cgroup.memory=nokmem, the deferred split > shrinker is quietly demoted to a non-memcg-aware one. As a result, > partially unmapped THPs are only split under global reclaim; memcg > (limit-induced) reclaim never splits them, so a cgroup under memory > pressure keeps its underused THPs intact. > > This is a regression from commit fafaeceb89a5 ("mm: switch deferred > split shrinker to list_lru"), which re-registered the shrinker without > SHRINKER_NONSLAB. The shrinker had carried this flag since commit > 0a432dcbeb32 ("mm: shrinker: make shrinker not depend on memcg kmem") > precisely so it would keep working with kmem accounting disabled. > Without the flag, shrinker_memcg_alloc() fails with -ENOSYS under > nokmem and the shrinker loses its memcg awareness. > > This was noticed by Michal during review of the patch "mm/list_lru: > don't copy stale shrinker id from non-memcg-aware shrinkers" [1]. > > Restore the flag. > > [1] https://lore.kernel.org/lkml/697713c4-0857-485b-aba7-c74f37a3c8b4@linux.alibaba.com/ > > Fixes: fafaeceb89a5 ("mm: switch deferred split shrinker to list_lru") > Suggested-by: Michal Koutný > Signed-off-by: Qinyun Tan > --- > mm/huge_memory.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 644d6905b49cc..16f9aa5b2d077 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -1022,7 +1022,8 @@ int folio_memcg_alloc_deferred(struct folio *folio) > static int __init thp_shrinker_init(void) > { > deferred_split_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE | > - SHRINKER_MEMCG_AWARE, > + SHRINKER_MEMCG_AWARE | > + SHRINKER_NONSLAB, > "thp-deferred_split"); > if (!deferred_split_shrinker) > return -ENOMEM; Acked-by: Usama Arif