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=-9.8 required=3.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,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 1DD01C4CEC7 for ; Sun, 15 Sep 2019 16:52:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CCDAB214D8 for ; Sun, 15 Sep 2019 16:52:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="jo+e4APs" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CCDAB214D8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7BE0D6B000A; Sun, 15 Sep 2019 12:52:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 76ED56B000C; Sun, 15 Sep 2019 12:52:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 65CE06B000D; Sun, 15 Sep 2019 12:52:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0212.hostedemail.com [216.40.44.212]) by kanga.kvack.org (Postfix) with ESMTP id 42BFC6B000A for ; Sun, 15 Sep 2019 12:52:50 -0400 (EDT) Received: from smtpin09.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id E09473AB9 for ; Sun, 15 Sep 2019 16:52:49 +0000 (UTC) X-FDA: 75937749258.09.story36_35c1c86a17631 X-HE-Tag: story36_35c1c86a17631 X-Filterd-Recvd-Size: 5096 Received: from mail-pg1-f194.google.com (mail-pg1-f194.google.com [209.85.215.194]) by imf05.hostedemail.com (Postfix) with ESMTP for ; Sun, 15 Sep 2019 16:52:49 +0000 (UTC) Received: by mail-pg1-f194.google.com with SMTP id 4so18002898pgm.12 for ; Sun, 15 Sep 2019 09:52:49 -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:in-reply-to:references :mime-version:content-transfer-encoding; bh=nii43oMTaFtktKbnijjugyrLFfb5ZKvbiN8kMj3vNPE=; b=jo+e4APs5xDRR8vZnH8rVBXMdzgGhpBwxw1z0mC3zae1JlCpMP62+atbzfzG4DzlJ4 weLCzW1zyxAYbUHZEPNrQtsLGmmxNCJWoa02cfILoRJfidraJ/kiXJgAl7L/E8Q0fs9c Dn/J+0SvCTaHBHWnlM2UnCAVBdLyy6KgR6bwLi7xR2wQwJ/MXLv8ynXcZwlUN4nwfe+s mxH+qYSu1vigjSVG1BrMLQUwD7FpJli522rbBGlbnGrt3xKG30eSKffnD0Y2HkDdyYzk pUuTC/IUU8TzL15qlK7Wzrw6vMLteSA9xTkhgzsInyxQftpd8Cy5PZjQZfwwplgw50+k yv6Q== 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:in-reply-to :references:mime-version:content-transfer-encoding; bh=nii43oMTaFtktKbnijjugyrLFfb5ZKvbiN8kMj3vNPE=; b=q1xwyv0EkZF7TOQ6iGnQFYzGsU10dFvU10JLyogVH8SEKT6ualKkWwPHyYe3h6EEWk fXwTHSNX5pbwwdLTWGBQqijWBP6pWBTYecj+kSybj91dPw+Tbl8cHwbv1mtfTDwLcmFj k3nlTUoGASUnMiD1vX6/8bi/qgl2snkT+6YiWl+W1FPIesndGmpQ1wjEJ6PHzGLni4lS I4DxEeuxymVL4gvcH6vIK9xEHW3cJPbJuVZ0ApiAztHyPtns0et169HN6KnmWAIjN52j ZzYveQoR1A9rGtIIGf4gbtUNxOiXUSKMw7X5sOyU0ILhxRAV8/vFKIGWvewCke012pnn qtdg== X-Gm-Message-State: APjAAAWvPk6fmBdiJlZYIoCouj6/HtgvLVgw1jIi3J618ivFu39GJMg4 U+EknxvyC1+T5VwbGTADkLQ= X-Google-Smtp-Source: APXvYqyTb4DRsLUcRsbIEyib6eSVHgjnGgZ0zUwvJ1lKLEu0+d9WiS+28E8PoS/0ro55mhxu8KF8iA== X-Received: by 2002:a62:7c4d:: with SMTP id x74mr7837018pfc.95.1568566368554; Sun, 15 Sep 2019 09:52:48 -0700 (PDT) Received: from localhost.localdomain.localdomain ([2408:823c:c11:160:b8c3:8577:bf2f:3]) by smtp.gmail.com with ESMTPSA id a4sm4383259pgq.6.2019.09.15.09.52.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 15 Sep 2019 09:52:48 -0700 (PDT) From: Pengfei Li To: akpm@linux-foundation.org Cc: vbabka@suse.cz, cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, guro@fb.com, Pengfei Li Subject: [PATCH v4 4/7] mm, slab: Return ZERO_SIZE_ALLOC for zero sized kmalloc requests Date: Mon, 16 Sep 2019 00:51:15 +0800 Message-Id: <20190915165121.7237-7-lpf.vector@gmail.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190915165121.7237-1-lpf.vector@gmail.com> References: <20190915165121.7237-1-lpf.vector@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable 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: This is a preparation patch, just replace 0 with ZERO_SIZE_ALLOC as the return value of zero sized requests. Signed-off-by: Pengfei Li --- include/linux/slab.h | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/include/linux/slab.h b/include/linux/slab.h index e773e5764b7b..1f05f68f2c3e 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -121,14 +121,20 @@ #define SLAB_DEACTIVATED ((slab_flags_t __force)0x10000000U) =20 /* - * ZERO_SIZE_PTR will be returned for zero sized kmalloc requests. + * ZERO_SIZE_ALLOC will be returned by kmalloc_index() if it was zero si= zed + * requests. * + * After that, ZERO_SIZE_PTR will be returned by the function that calle= d + * kmalloc_index(). + * Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault. * * ZERO_SIZE_PTR can be passed to kfree though in the same way that NULL= can. * Both make kfree a no-op. */ -#define ZERO_SIZE_PTR ((void *)16) +#define ZERO_SIZE_ALLOC (UINT_MAX) + +#define ZERO_SIZE_PTR ((void *)16) =20 #define ZERO_OR_NULL_PTR(x) ((unsigned long)(x) <=3D \ (unsigned long)ZERO_SIZE_PTR) @@ -350,7 +356,7 @@ static __always_inline enum kmalloc_cache_type kmallo= c_type(gfp_t flags) static __always_inline unsigned int kmalloc_index(size_t size) { if (!size) - return 0; + return ZERO_SIZE_ALLOC; =20 if (size <=3D KMALLOC_MIN_SIZE) return KMALLOC_SHIFT_LOW; @@ -546,7 +552,7 @@ static __always_inline void *kmalloc(size_t size, gfp= _t flags) #ifndef CONFIG_SLOB index =3D kmalloc_index(size); =20 - if (!index) + if (index =3D=3D ZERO_SIZE_ALLOC) return ZERO_SIZE_PTR; =20 return kmem_cache_alloc_trace( @@ -564,7 +570,7 @@ static __always_inline void *kmalloc_node(size_t size= , gfp_t flags, int node) size <=3D KMALLOC_MAX_CACHE_SIZE) { unsigned int i =3D kmalloc_index(size); =20 - if (!i) + if (i =3D=3D ZERO_SIZE_ALLOC) return ZERO_SIZE_PTR; =20 return kmem_cache_alloc_node_trace( --=20 2.21.0