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[209.85.220.65]) by mx.google.com with SMTPS id v10sor21963720plg.28.2019.07.08.10.06.56 for (Google Transport Security); Mon, 08 Jul 2019 10:06:57 -0700 (PDT) Received-SPF: pass (google.com: domain of lpf.vector@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=nE4pF6WC; spf=pass (google.com: domain of lpf.vector@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=lpf.vector@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com 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-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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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