From nobody Wed Sep 17 17:44:22 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 16BD7C4332F for ; Sat, 17 Dec 2022 01:57:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230310AbiLQB44 (ORCPT ); Fri, 16 Dec 2022 20:56:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33888 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230081AbiLQB4Y (ORCPT ); Fri, 16 Dec 2022 20:56:24 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3B9294AF14 for ; Fri, 16 Dec 2022 17:55:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1671242117; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=04/RfLLW+utGDl2gGNjOPJkeYdkxOAnoWfhoc+UAnVc=; b=Av+JIrn0XfrOzOa+eplw6v+yefPTTenTCDN9u1pKvdqYzfA7Zos3xwuQP14DgKddYaDR0I Ru6pTDbjeuyzEvoeYkbxodty4lsnHBuMpXbpfIYXYDF1D/tMpJ13isz5T6yYdKdatkVH8g g9eQjJOnZmN7qik51XDO80F6Fosr5Uo= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-646-p7aGxOkiMEGk7SjP7CbKLQ-1; Fri, 16 Dec 2022 20:55:12 -0500 X-MC-Unique: p7aGxOkiMEGk7SjP7CbKLQ-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 78BBA811E6E; Sat, 17 Dec 2022 01:55:11 +0000 (UTC) Received: from MiWiFi-R3L-srv.redhat.com (ovpn-12-34.pek2.redhat.com [10.72.12.34]) by smtp.corp.redhat.com (Postfix) with ESMTP id 752AF49BB6A; Sat, 17 Dec 2022 01:55:06 +0000 (UTC) From: Baoquan He To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, urezki@gmail.com, stephen.s.brennan@oracle.com, willy@infradead.org, akpm@linux-foundation.org, hch@infradead.org, Baoquan He Subject: [PATCH v2 5/7] mm/vmalloc: skip the uninitilized vmalloc areas Date: Sat, 17 Dec 2022 09:54:33 +0800 Message-Id: <20221217015435.73889-6-bhe@redhat.com> In-Reply-To: <20221217015435.73889-1-bhe@redhat.com> References: <20221217015435.73889-1-bhe@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" For areas allocated via vmalloc_xxx() APIs, it searches for unmapped area to reserve and allocates new pages to map into, please see function __vmalloc_node_range(). During the process, flag VM_UNINITIALIZED is set in vm->flags to indicate that the pages allocation and mapping haven't been done, until clear_vm_uninitialized_flag() is called to clear it. For this kind of area, if VM_UNINITIALIZED is still set, let's ignore it in vread() because pages newly allocated and being mapped in that area only contains zero data. reading them out by aligned_vread() is wasting time. Signed-off-by: Baoquan He --- mm/vmalloc.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 3bfa872a4513..bdaceda1b878 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -3617,6 +3617,11 @@ long vread(char *buf, char *addr, unsigned long coun= t) if (!vm && !flags) continue; =20 + if (vm->flags & VM_UNINITIALIZED) + continue; + /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */ + smp_rmb(); + vaddr =3D (char *) va->va_start; size =3D flags ? va_size(va) : get_vm_area_size(vm); =20 --=20 2.34.1