From nobody Wed Sep 10 01:53:16 2025 Received: from out-181.mta0.migadu.com (out-181.mta0.migadu.com [91.218.175.181]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 734991F4262 for ; Fri, 5 Sep 2025 20:16:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.181 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757103395; cv=none; b=ug91WezhJ9TMsN4kfbXu0hYQEa29eNDXXp/9CtHE+ADpcHL+j95sx5bIMAuSyJPl6SvAEc1FMgcHyQxMksCYEkQn+flnaYioCukqVDzbIjrsDH21qG0ZAENJRAHy3UKzAQ/9fsFLNBlLiyk5/S/166dobtBW4ATyfkiiu1xiDP8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757103395; c=relaxed/simple; bh=PYydNVuJVxyjN/9o+HwTZKEJHyaF9EPelKAywftw3Gg=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=UfhyhHltBgnxBUDIpeG/fnjThvah5tiaRkryCQSZHO3/El4Y5zom3Y/6BgT3wS+sAe6K2z3xVNCF+sTNniKkTDlGYzqOVCeRI4x6AlD/DgQGLh+s1V60nW6WCafcjwGZXE7z6JcfPJgXG9slhbI7eA3l43O8z9XVTmRj1qRJok4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=QV2b/Sbb; arc=none smtp.client-ip=91.218.175.181 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="QV2b/Sbb" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1757103380; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=3YYDb0qAcN44JOLdZSoQVTNxvRczokE6j4vJhbAzTIg=; b=QV2b/Sbb4ipL5cZ9a9yJcNo8hdOASLTVa0TacgojNu7sZz20c2/nXWVL6boHbYt6djjB1S /OSgqE5jk4RYujgEEObAjaPqUIlE0+Uct8TGkoUtVptEPursmz+4wJNShlouI3aDznj5Ur xykcBXyVbRz92uQuPK1tNJxXM8sExhY= From: Shakeel Butt To: Andrew Morton Cc: Tejun Heo , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Alexei Starovoitov , Peilin Ye , Kumar Kartikeya Dwivedi , bpf@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team Subject: [PATCH] memcg: skip cgroup_file_notify if spinning is not allowed Date: Fri, 5 Sep 2025 13:16:06 -0700 Message-ID: <20250905201606.66198-1-shakeel.butt@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" Generally memcg charging is allowed from all the contexts including NMI where even spinning on spinlock can cause locking issues. However one call chain was missed during the addition of memcg charging from any context support. That is try_charge_memcg() -> memcg_memory_event() -> cgroup_file_notify(). The possible function call tree under cgroup_file_notify() can acquire many different spin locks in spinning mode. Some of them are cgroup_file_kn_lock, kernfs_notify_lock, pool_workqeue's lock. So, let's just skip cgroup_file_notify() from memcg charging if the context does not allow spinning. Signed-off-by: Shakeel Butt Acked-by: Michal Hocko Tested-by: Peilin Ye --- include/linux/memcontrol.h | 23 ++++++++++++++++------- mm/memcontrol.c | 7 ++++--- 2 files changed, 20 insertions(+), 10 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 9dc5b52672a6..054fa34c936a 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -993,22 +993,25 @@ static inline void count_memcg_event_mm(struct mm_str= uct *mm, count_memcg_events_mm(mm, idx, 1); } =20 -static inline void memcg_memory_event(struct mem_cgroup *memcg, - enum memcg_memory_event event) +static inline void __memcg_memory_event(struct mem_cgroup *memcg, + enum memcg_memory_event event, + bool allow_spinning) { bool swap_event =3D event =3D=3D MEMCG_SWAP_HIGH || event =3D=3D MEMCG_SW= AP_MAX || event =3D=3D MEMCG_SWAP_FAIL; =20 atomic_long_inc(&memcg->memory_events_local[event]); - if (!swap_event) + if (!swap_event && allow_spinning) cgroup_file_notify(&memcg->events_local_file); =20 do { atomic_long_inc(&memcg->memory_events[event]); - if (swap_event) - cgroup_file_notify(&memcg->swap_events_file); - else - cgroup_file_notify(&memcg->events_file); + if (allow_spinning) { + if (swap_event) + cgroup_file_notify(&memcg->swap_events_file); + else + cgroup_file_notify(&memcg->events_file); + } =20 if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) break; @@ -1018,6 +1021,12 @@ static inline void memcg_memory_event(struct mem_cgr= oup *memcg, !mem_cgroup_is_root(memcg)); } =20 +static inline void memcg_memory_event(struct mem_cgroup *memcg, + enum memcg_memory_event event) +{ + __memcg_memory_event(memcg, event, true); +} + static inline void memcg_memory_event_mm(struct mm_struct *mm, enum memcg_memory_event event) { diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 257d2c76b730..dd5cd9d352f3 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2306,12 +2306,13 @@ static int try_charge_memcg(struct mem_cgroup *memc= g, gfp_t gfp_mask, bool drained =3D false; bool raised_max_event =3D false; unsigned long pflags; + bool allow_spinning =3D gfpflags_allow_spinning(gfp_mask); =20 retry: if (consume_stock(memcg, nr_pages)) return 0; =20 - if (!gfpflags_allow_spinning(gfp_mask)) + if (!allow_spinning) /* Avoid the refill and flush of the older stock */ batch =3D nr_pages; =20 @@ -2347,7 +2348,7 @@ static int try_charge_memcg(struct mem_cgroup *memcg,= gfp_t gfp_mask, if (!gfpflags_allow_blocking(gfp_mask)) goto nomem; =20 - memcg_memory_event(mem_over_limit, MEMCG_MAX); + __memcg_memory_event(mem_over_limit, MEMCG_MAX, allow_spinning); raised_max_event =3D true; =20 psi_memstall_enter(&pflags); @@ -2414,7 +2415,7 @@ static int try_charge_memcg(struct mem_cgroup *memcg,= gfp_t gfp_mask, * a MEMCG_MAX event. */ if (!raised_max_event) - memcg_memory_event(mem_over_limit, MEMCG_MAX); + __memcg_memory_event(mem_over_limit, MEMCG_MAX, allow_spinning); =20 /* * The allocation either can't fail or will lead to more memory --=20 2.47.3