From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5E0E0C606C2 for ; Mon, 8 Jul 2019 17:06:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 32CE920693 for ; Mon, 8 Jul 2019 17:06:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="nE4pF6WC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390011AbfGHRG5 (ORCPT ); Mon, 8 Jul 2019 13:06:57 -0400 Received: from mail-pl1-f196.google.com ([209.85.214.196]:46198 "EHLO mail-pl1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730562AbfGHRG5 (ORCPT ); Mon, 8 Jul 2019 13:06:57 -0400 Received: by mail-pl1-f196.google.com with SMTP id c2so7019095plz.13 for ; Mon, 08 Jul 2019 10:06:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=5b7anIeqnAhA6BO/lx8yoH/EvcoMVwex3ww0hx0nIBk=; b=nE4pF6WCSfy5375pasiGnK6x/BoAlKvJiEjKHA1Z6LC61rUtkohvgs+pMqeqoxrHeJ QaoQIYQBVzZdYmyimFzvOOvkufThmb+yZ/4JPuZk6Vll7Vgc2aPjWaiSruazPDixu8y+ MC4cvlyfnXnFY2cPZh2uu8o6bDhtz0x/6j8cB//biI5O9TvD9bC+T/gL5B5tf7CHvRYr RxFPEo/q+Y4ypdM2KWGRBpOJoOMygvy5tt61wahtCaSnBQ7/twQqoocOOgu+BscuktVJ YlpYTN9kzOINtxTO6MsLndbEJJry/TBKMD8GLviUttA82JUu2V4o6hu6UgvfMjPuHWlN OseQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=5b7anIeqnAhA6BO/lx8yoH/EvcoMVwex3ww0hx0nIBk=; b=D0ef6vWKSvlE+JV5enMx4wJwSlc7zJdMyOrvEEU07QbGH7loJPW1rqhzsLUMNr/miR be3ri79bY6NyNRXj9fMoKzSW+KFBuOrUbBApv94lIequC7qdOIiPM/RbQI4ex/WgQ6+p 2tZhlwATjXAFSZl4KncI86yRXQzJUP4MAW8nmxXrR2ZOpAgy2vhQsz4IbcOdkukbybIj RCWpq1czyakDqzhshRmwKVICBtZWMLNSaA+U6j1PIG1DABlv2AkaYpltMwmpqzJ/aP8x QHp+APcAyBbB5RpSnphZCm17to49LE5iwVomsmMm2L8CzeoDQwAACtgJ37G2izAL7kdB 47gQ== X-Gm-Message-State: APjAAAX2YGHjU22Zx+r3586V1fSXQJuUlmCFZY/tiA85/qcjHd38AZa6 4QFpBww9QQ2Ot+uMZO9z5nM= X-Google-Smtp-Source: APXvYqzt+il4zwPT6FRB06smT4nafOFmaW59SnLzajCBM2ImXEDODHJR8LpJ1IuBFwxXC7wAgigEgg== X-Received: by 2002:a17:902:6a85:: with SMTP id n5mr24841812plk.73.1562605616776; Mon, 08 Jul 2019 10:06:56 -0700 (PDT) Received: from localhost.localdomain.localdomain ([2408:823c:c11:b30:b8c3:8577:bf2f:2]) by smtp.gmail.com with ESMTPSA id 30sm149551pjk.17.2019.07.08.10.06.48 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 08 Jul 2019 10:06:56 -0700 (PDT) From: Pengfei Li To: akpm@linux-foundation.org Cc: urezki@gmail.com, rpenyaev@suse.de, peterz@infradead.org, guro@fb.com, rick.p.edgecombe@intel.com, rppt@linux.ibm.com, aryabinin@virtuozzo.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Pengfei Li Subject: [PATCH] mm/vmalloc.c: Remove always-true conditional in vmap_init_free_space Date: Tue, 9 Jul 2019 01:06:31 +0800 Message-Id: <20190708170631.2130-1-lpf.vector@gmail.com> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When unsigned long variables are subtracted from one another, the result is always non-negative. The vmap_area_list is sorted by address. So the following two conditions are always true. 1) if (busy->va_start - vmap_start > 0) 2) if (vmap_end - vmap_start > 0) Just remove them. Signed-off-by: Pengfei Li --- mm/vmalloc.c | 32 +++++++++++++------------------- 1 file changed, 13 insertions(+), 19 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 0f76cca32a1c..c7bdbdc18472 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1810,31 +1810,25 @@ static void vmap_init_free_space(void) * |<--------------------------------->| */ list_for_each_entry(busy, &vmap_area_list, list) { - if (busy->va_start - vmap_start > 0) { - free = kmem_cache_zalloc(vmap_area_cachep, GFP_NOWAIT); - if (!WARN_ON_ONCE(!free)) { - free->va_start = vmap_start; - free->va_end = busy->va_start; - - insert_vmap_area_augment(free, NULL, - &free_vmap_area_root, - &free_vmap_area_list); - } - } - - vmap_start = busy->va_end; - } - - if (vmap_end - vmap_start > 0) { free = kmem_cache_zalloc(vmap_area_cachep, GFP_NOWAIT); if (!WARN_ON_ONCE(!free)) { free->va_start = vmap_start; - free->va_end = vmap_end; + free->va_end = busy->va_start; insert_vmap_area_augment(free, NULL, - &free_vmap_area_root, - &free_vmap_area_list); + &free_vmap_area_root, &free_vmap_area_list); } + + vmap_start = busy->va_end; + } + + free = kmem_cache_zalloc(vmap_area_cachep, GFP_NOWAIT); + if (!WARN_ON_ONCE(!free)) { + free->va_start = vmap_start; + free->va_end = vmap_end; + + insert_vmap_area_augment(free, NULL, + &free_vmap_area_root, &free_vmap_area_list); } } -- 2.21.0