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=-15.9 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1, USER_IN_DEF_DKIM_WL 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 D1B35C33C9E for ; Wed, 15 Jan 2020 01:58:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9E6DE24679 for ; Wed, 15 Jan 2020 01:58:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="rp40sf94" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728909AbgAOB6i (ORCPT ); Tue, 14 Jan 2020 20:58:38 -0500 Received: from mail-pl1-f196.google.com ([209.85.214.196]:35951 "EHLO mail-pl1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728882AbgAOB6i (ORCPT ); Tue, 14 Jan 2020 20:58:38 -0500 Received: by mail-pl1-f196.google.com with SMTP id a6so6100021plm.3 for ; Tue, 14 Jan 2020 17:58:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:user-agent:mime-version; bh=fj5c4UIrwrHuebCnymMMYIFQTDYFE/X+bvsiYmpq1Rk=; b=rp40sf94iCEseNvhH50Jdc6oYJ86AKGlN+xQYpJeK1VMwb6JRd2kU1FwlPEuRsWOgG hsQkXNJ3e/tUuqqEQY/m+jjKwKoHayO6J5kXj4zv6kLZRc+B/ofINmXQrFJWsLj/5Pi6 f3xl6aoH8pYHbyNccC+LvUJ1AiiZZBdHE9gLsj/7QZpxPQFxC7W3ZkkWC5HZotUMisMj 9elVQEz5uMUgUGHnu0/Ps13cnWB3cermPzMjh/u+As8TMPfB27Q6z4QZNMyUXuQgd0yI yGMzs5dVse9AYzVxXI5BDhihKFC3UoDSubrflA3nuOGDl2Q6pq7qwbDXfJaOGtEO886X fuOQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:user-agent :mime-version; bh=fj5c4UIrwrHuebCnymMMYIFQTDYFE/X+bvsiYmpq1Rk=; b=lMOwT1Kk6b7blSqHEzltwOhXMlEzYDmsI27G21stMzC3zTzvvx0bTnCjoniiBgjeps uOSozTGIxto7ezM123dz3+TR6oOKGpZ64IzM1QPOgui8ypF5DOQPzkbib5sufaXPO4bo UYmEf31EmUN2Y+PY1rqUfOu2rZ2la38JcWg72bmiQWF2L7W5dpuwv891cYrms7gg+QzE nskfNTSdA8RxRVVHw7RF566BAIX7b8rJsCFn3tE5rx1EAbkAKp1tDSCVDtLpGarVIbm4 a/CS6LuqNE/PUVccu1nNhhn+7zV0ahLHBusBwS9yvQs1fhIYGS4Sj8kSwxVzD8BJPoy3 sAmQ== X-Gm-Message-State: APjAAAXtyIAie8pXY2zl3iwcc+kxWDdNk+UGDAv4rhsjqkK6baoJ1Psh sbTgSwoat0Bt9SXa902HyEWvpQ== X-Google-Smtp-Source: APXvYqyPSthc9ZtJ5YzXVGQgIPCZZDAyRXEc85YTMs1GQxMFcjiC8jCWCdzTe75XV+KW4Mf/Rfm1LA== X-Received: by 2002:a17:90a:d807:: with SMTP id a7mr33633296pjv.15.1579053517840; Tue, 14 Jan 2020 17:58:37 -0800 (PST) Received: from [2620:15c:17:3:3a5:23a7:5e32:4598] ([2620:15c:17:3:3a5:23a7:5e32:4598]) by smtp.gmail.com with ESMTPSA id g9sm19978122pfm.150.2020.01.14.17.58.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Jan 2020 17:58:37 -0800 (PST) Date: Tue, 14 Jan 2020 17:58:36 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Andrew Morton cc: Mel Gorman , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [patch] mm, thp: fix defrag setting if newline is not used Message-ID: User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If thp defrag setting "defer" is used and a newline is *not* used when writing to the sysfs file, this is interpreted as the "defer+madvise" option. This is because we do prefix matching and if five characters are written without a newline, the current code ends up comparing to the first five bytes of the "defer+madvise" option and using that instead. Find the length of what the user is writing and use that to guide our decision on which string comparison to do. Fixes: 21440d7eb904 ("mm, thp: add new defer+madvise defrag option") Signed-off-by: David Rientjes --- This can be done in *many* different ways including extracting logic to a helper function. If someone would like this to be implemented differently, please suggest it. mm/huge_memory.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -250,32 +250,33 @@ static ssize_t defrag_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count) { - if (!memcmp("always", buf, - min(sizeof("always")-1, count))) { + size_t len = count; + + /* For prefix matching, find the length of interest */ + if (buf[len-1] == '\n') + len--; + + if (len == sizeof("always")-1 && !memcmp("always", buf, len)) { clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); - } else if (!memcmp("defer+madvise", buf, - min(sizeof("defer+madvise")-1, count))) { + } else if (len == sizeof("defer+madvise")-1 && !memcmp("defer+madvise", buf, len)) { clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); - } else if (!memcmp("defer", buf, - min(sizeof("defer")-1, count))) { + } else if (len == sizeof("defer")-1 && !memcmp("defer", buf, len)) { clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); - } else if (!memcmp("madvise", buf, - min(sizeof("madvise")-1, count))) { + } else if (len == sizeof("madvise")-1 && !memcmp("madvise", buf, len)) { clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); - } else if (!memcmp("never", buf, - min(sizeof("never")-1, count))) { + } else if (len == sizeof("never")-1 && !memcmp("never", buf, len)) { clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);