From nobody Sun Feb 8 22:56:58 2026 Received: from out203-205-221-164.mail.qq.com (out203-205-221-164.mail.qq.com [203.205.221.164]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D510A1F12F8 for ; Fri, 12 Dec 2025 07:09:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=203.205.221.164 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765523371; cv=none; b=IyYuFDGePH0r8mjqM5Jh+SRjFRLDbKr7/dpayQqlLxfKV5mf3En72jkE8+DAE3lc0sCbKwp5NFPUnpZoedK8S7ZU6ZmpK6WcIEYJCvOBTI6RGXpdsiT/L3nCWHxBhpyaCv33MGPzwvxkjuHu+pAyhDsKU4VbEftBi9VHxHekV/8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765523371; c=relaxed/simple; bh=cQuNOiPb2RZKR0WBnJarwM3hPtBxk4RmR/dJygrSiGw=; h=Message-ID:From:To:Cc:Subject:Date:MIME-Version:Content-Type; b=izRxy9jpJ++vzPptgAiCwT/lE8Z2hxSFIEz2ENvxx3mqUfm7w7kFf+2DWK4KL9mFP0dzeeZHYumfS78l43VdCTokXu75eDDD8MgS1YcDQORI/E1sGwQAGZefU4OBzcOP5IrB3qCGUoeDnN+LqbkY3emn1jxGtt8MHUhpw+Q5a+0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=qq.com; spf=pass smtp.mailfrom=qq.com; dkim=pass (1024-bit key) header.d=qq.com header.i=@qq.com header.b=r2VaPkgp; arc=none smtp.client-ip=203.205.221.164 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=qq.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=qq.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=qq.com header.i=@qq.com header.b="r2VaPkgp" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=qq.com; s=s201512; t=1765523364; bh=IXNkv6VDsX+5RxmtyeI90QUmoZKQ3Q77u5K0IV6GAqY=; h=From:To:Cc:Subject:Date; b=r2VaPkgpSpUD9wthSVKnlmNYzS7oXowkmLbknut0mv/E8lCsod5yv4XjdoyES7Yqm 3xhaAjbQMugX9HUcruaU4oUbec3mYfjpUKfZ/6+vfKgUT2izBx4QCw4PNKcvEprFHl p1vGL8u46bNTaLv/ntDdidL1VmsCvYQzFCBBtcBM= Received: from compass-pc.sustech.edu.cn ([116.7.234.240]) by newxmesmtplogicsvrszc43-0.qq.com (NewEsmtp) with SMTP id 2560E84B; Fri, 12 Dec 2025 15:09:22 +0800 X-QQ-mid: xmsmtpt1765523362t466ehdmn Message-ID: X-QQ-XMAILINFO: NnYhxYSyuBnLxXPBpZ5nZNUa9x5wz+dRk4u0AaFol8ukPFP689jVoMyjEm2vvJ V6mx1LEYOQiDURQXLw1Bkj70LKG6zwchaMcO+4p0OIZ12PxCUyAYY34YAR3Z8B8EK+seJ9abwnpg 5AGOeL3gayd4w/wokklye+RtSXV0WV2akmYxfUCpLFKLkDyIIUgO68VdzFQF+AGDr7a/ye3bz5NI vU3Arw4OxLInPi6H7TiqxE3gijqw02Ml8MOo/9w+wlKsQRqtNqyY8DLQgFuzIF569aDrpLgYTwuP PDZ7N9AQ3n8uqAeCeL1Dh77DoFpxhdHbwwoOjYIjtL3NSm0lZ68Gk8xR4rBnTvtF9XRVEOfwzguV i0dEzugQMhjQHQxqUbMN24c96ozxlrHngXehRGGpFkIw3yYGcQ3yiLF2+q/XLpEGwHLujRQ8bpvw otVCe3eYnMkhavpY9I0XvsG7d4vabfz1Yz0QM0en/pdTSsYx2YmUA8VM0vnK0opa2FpShEIrxEQ8 Gj8+PJiEB1OSiEPRTvr3j1BB9nzjlDdKs8emy58aEn0xnWmGSA43LgnMgl5ffCAuewm5tQzl2WAN dA+uWkWrm+jdrpjJhj43QKstExbyShJ/MBlgWO1faHItv507AWyJecobAlVYglLPdU17fBqmto8T 0avQU2IE0BM4x/V5Mt6DYlWTL6BazcC6Hx5DFnvT9DlnJ9TG+1/Zhgh3alkZSaab7xCv9L/biGsJ On5sUiH7+zh3nZe36HGLRKH7t+bFwjv02qEZJ5chLEnROeqHEIhGUIlFYttDCwAJDRq6PkwOtCZQ kSxpSZkdrL3KYnyG14EXYtFxQBobUTsXRaHO3N3sD8mtRO7htinOn4sIiW8patb1cgJt11yFZdAq iutExiRISz9gfWsq0SfbTcIV/l07VTin7vZbeQiYo+p4jLM/I0H6ynLpOPOhRbUZAS4zST1FqWpa PtAe5Qt0ER4u7lTCNwjjK1QQhWL/PqbC4hWcF2NIqq/sPxcGA9nDO0TJNhT4Q3OITewGvE77wb2i 890X8j3uZz/8rDy4ACnerPq/6U5BU= X-QQ-XMRINFO: OWPUhxQsoeAVDbp3OJHYyFg= From: Yankai Xu <815559068@qq.com> To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, akpm@linux-foundation.org, Yankai Xu <815559068@qq.com> Subject: [PATCH v2] mm/gfp: cast GFP_ZONE_TABLE entries to long to avoid shift overflow Date: Fri, 12 Dec 2025 15:09:16 +0800 X-OQ-MSGID: <20251212070916.1352555-1-815559068@qq.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable When a new zone is added to enum zone_type in mmzone.h, the existing GFP_ZONE_TABLE macro causes a compile-time shift overflow: CC arch/x86/kernel/asm-offsets.s In file included from ./include/linux/slab.h:16, from ./include/linux/crypto.h:18, from arch/x86/kernel/asm-offsets.c:9: ./include/linux/gfp.h: In function =E2=80=98gfp_zone=E2=80=99: ./include/linux/gfp.h:132:27: error: left shift count >=3D width of type = [-Werror=3Dshift-count-overflow] 132 | | (OPT_ZONE_DMA32 << (___GFP_MOVABLE | ___GFP_DMA32) * GF= P_ZONES_SHIFT)\ | ^~ ./include/linux/gfp.h:157:14: note: in expansion of macro =E2=80=98GFP_ZO= NE_TABLE=E2=80=99 157 | z =3D (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) & | This can be reproduced by adding a new zone: @@ -868,6 +868,7 @@ enum zone_type { #ifdef CONFIG_ZONE_DEVICE ZONE_DEVICE, #endif + ZONE_FOO, __MAX_NR_ZONES }; This happens because the left-hand side operands of the shifts inside GFP_Z= ONE_TABLE are enum zone_type, which is of type int. The shift is logically = valid because it has been checked by 16 * GFP_ZONES_SHIFT > BITS_PER_LONG p= reviously. Fixed this by casting each value in GFP_ZONE_TABLE to type long. Signed-off-by: Yankai Xu <815559068@qq.com> --- v2: - Added compiler warning messages and reproduce steps --- include/linux/gfp.h | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/include/linux/gfp.h b/include/linux/gfp.h index b155929af..e694f3103 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -122,14 +122,14 @@ static inline bool gfpflags_allow_spinning(const gfp_= t gfp_flags) #endif #define GFP_ZONE_TABLE ( \ - (ZONE_NORMAL << 0 * GFP_ZONES_SHIFT) \ - | (OPT_ZONE_DMA << ___GFP_DMA * GFP_ZONES_SHIFT) \ - | (OPT_ZONE_HIGHMEM << ___GFP_HIGHMEM * GFP_ZONES_SHIFT) \ - | (OPT_ZONE_DMA32 << ___GFP_DMA32 * GFP_ZONES_SHIFT) \ - | (ZONE_NORMAL << ___GFP_MOVABLE * GFP_ZONES_SHIFT) \ - | (OPT_ZONE_DMA << (___GFP_MOVABLE | ___GFP_DMA) * GFP_ZONES_SHIFT) \ - | (ZONE_MOVABLE << (___GFP_MOVABLE | ___GFP_HIGHMEM) * GFP_ZONES_SHIFT)\ - | (OPT_ZONE_DMA32 << (___GFP_MOVABLE | ___GFP_DMA32) * GFP_ZONES_SHIFT)\ + ((long)ZONE_NORMAL << 0 * GFP_ZONES_SHIFT) \ + | ((long)OPT_ZONE_DMA << ___GFP_DMA * GFP_ZONES_SHIFT) \ + | ((long)OPT_ZONE_HIGHMEM << ___GFP_HIGHMEM * GFP_ZONES_SHIFT) \ + | ((long)OPT_ZONE_DMA32 << ___GFP_DMA32 * GFP_ZONES_SHIFT) \ + | ((long)ZONE_NORMAL << ___GFP_MOVABLE * GFP_ZONES_SHIFT) \ + | ((long)OPT_ZONE_DMA << (___GFP_MOVABLE | ___GFP_DMA) * GFP_ZONES_SHIFT)= \ + | ((long)ZONE_MOVABLE << (___GFP_MOVABLE | ___GFP_HIGHMEM) * GFP_ZONES_SH= IFT)\ + | ((long)OPT_ZONE_DMA32 << (___GFP_MOVABLE | ___GFP_DMA32) * GFP_ZONES_SH= IFT)\ ) /* -- 2.43.0