From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.72 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793393685; b=INgkEn8poAIWCLy6nsoq8GnMLwhyEVh86kjIWTXX1rKck6xniy4vgU6ZPnFs41uVooHt RTiQ7u4PbEkixGXSRNIJ1JvSCXDV1btlKJUyYmMEXgFLmy3IQyY0k0zbsvYmcuqJ+f5Tz fyeNJe8apVnuDQsSLz+onoAhhgHKbTZhT/MKDXwzZzjyXnqMKbW77KPntqDPrbP8Ccqma BjbRcdTfjfTyqZO3owgH74OErsdb48huIyTezG2SdQqc7guEL9C/IbtMyDv4LnTYmMjeY iAC/w+DfoArsif+qKeEln13GLGq5CEWhU51A4B+QVD9HDCOciQk86V85fIqZGpzVqLw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793393685; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:From:To:Cc:Subject:Date:Message-ID: X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=WvB6ePpKWWKwFI9dveLQEwy+mNq3q4b5hvoyCK6cGIg=; b=ues6tGUWJ8o6DljnDtIgbsEXkY3oYusVobFPXIkNXocvCK1od3/+AHm74HmhnaIetMfl BumD3qitF9pbb6pDTZqMWcsoN4C0As8jGAlDybvTGerL8+KhWLqkMcAggmESVREnNuf5x iIyH+rshxnwsIizmQx5e7eLuW+3VZ1MAS/d6tpgqMQLvf8jkp0FrUPemaz1GRiun/KdDM EVWCHwKF8C6lx1Nz2r4d63sDG3nJP8A0BRI+bpzr5UG+pmGW/wrbpw3iO1BZ0UXT6YSuX sQkjM+UJt6JswVuRWnF9fcT3RrV4VUEz0yuB5a3GW8S7wu+Vkzw9Zy7dsxqbSrTRuyA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=p6NdYS5x; arc=none smtp.remote-ip=91.218.175.72 Received: from mta0.migadu.com (out-72.mta0.migadu.com [91.218.175.72]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9E734606A323 for ; Fri, 30 Oct 2026 20:54:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 9E734606A323 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, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=p6NdYS5x X-Envelope-To: cgroups@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=PEe7LP+ea1c/6uQpUdYkMtQm9r7KkVekkLLCHeCHzrQ=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793393682; v=1; x=1793998482; b=p6NdYS5xu4Ofo3c7yLwGkEcBjz1wod2WxK6ICnQ+wq225o/TkjQYwGwM4h2TjCD6+B/KSu0f yWOLwKsoxbx81L8sko6x36MgAhTQ6w1AYPZrZRamW56w9KZfUiGrpM0H7Or/y0iGYj0eQji7C5u aoaw6OL7ZJWIs/pgs8LN/ZHk= X-Envelope-To: cgroups@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 9e68337c290a835a; Fri, 30 Oct 2026 20:54:42 +0000 X-Mizu-Trace-ID: 9e68337c290a835a X-Migadu-Flow: FLOW_OUT From: Shakeel Butt To: Andrew Morton Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Tejun Heo , Harry Yoo , Meta kernel team , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Michal Hocko Subject: [PATCH v2 3/5] memcg: use high_work for kernel threads Date: Fri, 30 Oct 2026 13:54:14 -0700 Message-ID: <20261030205418.341214-4-shakeel.butt@linux.dev> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261030205418.341214-1-shakeel.butt@linux.dev> References: <20261030205418.341214-1-shakeel.butt@linux.dev> X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Shakeel Butt Acked-by: Michal Hocko --- 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