From nobody Wed Dec 17 19:01:02 2025 Received: from out-188.mta0.migadu.com (out-188.mta0.migadu.com [91.218.175.188]) (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 7267614A614 for ; Fri, 4 Apr 2025 01:39:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.188 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743730798; cv=none; b=UREyyxAk2XizOivOSNSf/NquI/cCc26Zow2JYN7sme1ClFBBxFgQJxwQ2cqaoacM3MM62SXifGHqnzMLKfz5KtsD4ZHbR+z197jYtToMy1XTPrnO4KJjeUa6BI25+qKzWcEQ1td++WL9vOgyly9vVy5IK50FUR9TEUgcN6z9Cdw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743730798; c=relaxed/simple; bh=v8b9Fi3MhEJftF/PX1M+/Bkc3YxAYhK3++UVDF+VxEs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DstN+i3XvqJzIPB6qLmafmy6F4cKHZSeZDw6NJkfOl6oqO0otbK2UC0gGTGUk+CrvJged+AS061I7veK4yN2g9UOi1bTyTevBV0Eu1Chs07Y7CU/zOgc4vKQEEgSfd1ddeG9DZ51bNxiGWuChuPVOdmAzuxDa9ZgBL1TI++O9IE= 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=lJr61OEX; arc=none smtp.client-ip=91.218.175.188 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="lJr61OEX" 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=1743730794; 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: in-reply-to:in-reply-to:references:references; bh=zBVDPRxC7zGlf74XAtJaE4SLulN0IfYjtlemuQUW//g=; b=lJr61OEX4xx/9USfw1sohnqhrgFqNhWyygUyfhavSMJTjmL+JpCYHdT4JzRjko3+YFDyoA o3FvDnCdezFhTPYkauE78iHGzVxwYtbUgoDBBCLUDjGvT++701sTPl2fBbo0WZl525k4sd c3sIlCIGT1ABcv3k91f6uLqX/LRI9r0= From: Shakeel Butt To: Andrew Morton Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Vlastimil Babka , Sebastian Andrzej Siewior , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team Subject: [PATCH v2 5/9] memcg: no refilling stock from obj_cgroup_release Date: Thu, 3 Apr 2025 18:39:09 -0700 Message-ID: <20250404013913.1663035-6-shakeel.butt@linux.dev> In-Reply-To: <20250404013913.1663035-1-shakeel.butt@linux.dev> References: <20250404013913.1663035-1-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" obj_cgroup_release is called when all the references to the objcg have been released i.e. no more memory objects are pointing to it. Most probably objcg->memcg will be pointing to some ancestor memcg. In obj_cgroup_release(), the kernel calls obj_cgroup_uncharge_pages() which refills the local stock. There is no need to refill the local stock with some ancestor memcg and flush the local stock. Let's decouple obj_cgroup_release() from the local stock by uncharging instead of refilling. One additional benefit of this change is that it removes the requirement to only call obj_cgroup_put() outside of local_lock. Acked-by: Vlastimil Babka Reviewed-by: Roman Gushchin Signed-off-by: Shakeel Butt --- mm/memcontrol.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 03a2be6d4a67..df52084e90f4 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -129,8 +129,7 @@ bool mem_cgroup_kmem_disabled(void) return cgroup_memory_nokmem; } =20 -static void obj_cgroup_uncharge_pages(struct obj_cgroup *objcg, - unsigned int nr_pages); +static void memcg_uncharge(struct mem_cgroup *memcg, unsigned int nr_pages= ); =20 static void obj_cgroup_release(struct percpu_ref *ref) { @@ -163,8 +162,16 @@ static void obj_cgroup_release(struct percpu_ref *ref) WARN_ON_ONCE(nr_bytes & (PAGE_SIZE - 1)); nr_pages =3D nr_bytes >> PAGE_SHIFT; =20 - if (nr_pages) - obj_cgroup_uncharge_pages(objcg, nr_pages); + if (nr_pages) { + struct mem_cgroup *memcg; + + memcg =3D get_mem_cgroup_from_objcg(objcg); + mod_memcg_state(memcg, MEMCG_KMEM, -nr_pages); + memcg1_account_kmem(memcg, -nr_pages); + if (!mem_cgroup_is_root(memcg)) + memcg_uncharge(memcg, nr_pages); + mem_cgroup_put(memcg); + } =20 spin_lock_irqsave(&objcg_lock, flags); list_del(&objcg->list); --=20 2.47.1