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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id F0A9FC71148 for ; Fri, 13 Jun 2025 03:06:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6D4106B007B; Thu, 12 Jun 2025 23:06:06 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 684896B0089; Thu, 12 Jun 2025 23:06:06 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 59B0F6B008A; Thu, 12 Jun 2025 23:06:06 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 38DFD6B007B for ; Thu, 12 Jun 2025 23:06:06 -0400 (EDT) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 9C552160B98 for ; Fri, 13 Jun 2025 03:06:05 +0000 (UTC) X-FDA: 83548888290.16.514F30C Received: from out-187.mta1.migadu.com (out-187.mta1.migadu.com [95.215.58.187]) by imf13.hostedemail.com (Postfix) with ESMTP id C46452000A for ; Fri, 13 Jun 2025 03:06:03 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=LgrxKJal; spf=pass (imf13.hostedemail.com: domain of hao.ge@linux.dev designates 95.215.58.187 as permitted sender) smtp.mailfrom=hao.ge@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1749783964; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:references:dkim-signature; bh=79H2iL8yRwKJxUH4hjS5H+3mFY7cHIskQpfR41dr/Cg=; b=bbxp6Qb6G7985fxvrFwevL6/ZH9k308i9YMI9gxfgJGEhzhEHumfcK6VB1RksTqPkdyvVO d6ZE2Rl05OX6YnRBdCi5H5l5k9nXXp10yWQu1Jsrm/Mx6YrzSAMG1Be1Kob7INYCAVj/dX /iOPfpIR2xaT/lxgB5mj9QyAIo58Vw0= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=LgrxKJal; spf=pass (imf13.hostedemail.com: domain of hao.ge@linux.dev designates 95.215.58.187 as permitted sender) smtp.mailfrom=hao.ge@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1749783964; a=rsa-sha256; cv=none; b=loajuPIM+OzAhnVghAswyJDwwAsB3/A3VsVahTQHUiPumYKqIWyUQJ7V0u0cb5jJZGjeT8 tzNdOmUAV8LHe1on2HCtRNf2SfywXNMmbAHD4YS818Uvdtcvmxeq7KLnWAOKuEPf/nRbho 2no2L+EHrGjpDAjXn1GIOjyuY9cMz+4= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1749783960; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=79H2iL8yRwKJxUH4hjS5H+3mFY7cHIskQpfR41dr/Cg=; b=LgrxKJalnpIHKcvOlQxpXXyh23cer9UoHbXSdNiEqoufevAn+K+9zSSRAV3qDd8E7mLFGE nRt0/+48wUlaIxLLqLgw/0EeMV1zxXkjL4GPu2A1JEJqnQTF/YVeidIlraSL4UoKPPIZxr tIHFuCX5/f844z+Yp+t/YGzKBDlO2YY= From: Hao Ge To: Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Mike Rapoport , Richard Henderson , Matt Turner , Dennis Zhou , Tejun Heo , Christoph Lameter , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Kent Overstreet Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-s390@vger.kernel.org, Hao Ge , Hao Ge Subject: [PATCH v2 0/3] mm: Restrict the static definition of the per-CPU variable _shared_alloc_tag to s390 and alpha architectures only Date: Fri, 13 Jun 2025 11:05:04 +0800 Message-Id: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: C46452000A X-Rspamd-Server: rspam03 X-Rspam-User: X-Stat-Signature: e1bactpjgpzgwx71bonoy57zgupm8xoh X-HE-Tag: 1749783963-164116 X-HE-Meta: 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 c+XVKo6X w2ry/qpFsR/Rgo6COifEMb6rZLIB3cJxi+CzCkTtL29DkVNMsG6W2KvSa093pfm8aMCDJvPRAFsuky7RshOGTiGZf5GYTMIaQU9oC67WtwpZFmi0dI2iV+69+SAMqkw50OilBe66qr/jsGjwaWp8QwaeM0rown6gl2N3B2W8LbH1sSPOCODYRc73EHJGY7VfZIw8m2G+MGeSzj/JTrQo/rprCteVc/KtQUfPSo5BIN5+oc8ls0AT6i6zFww== 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: List-Subscribe: List-Unsubscribe: From: Hao Ge Recently discovered this entry while checking kallsyms on ARM64: ffff800083e509c0 D _shared_alloc_tag If ARCH_NEEDS_WEAK_PER_CPU is not defined((it is only defined for s390 and alpha architectures),there's no need to statically define the percpu variable _shared_alloc_tag. As the number of CPUs increases,the wasted memory will grow correspondingly. Therefore,we need to implement isolation for this purpose. However,currently ARCH_NEEDS_WEAK_PER_CPU is a #define and is enclosed within the #if defined(MODULE) conditional block. When building the core kernel code for s390 or alpha architectures, ARCH_NEEDS_WEAK_PER_CPU remains undefined (as it is gated by #if defined(MODULE)). However,when building modules for these architectures,the macro is explicitly defined. Therefore,we need to make ARCH_NEEDS_WEAK_PER_CPU a Kconfig option. And replace all instances of ARCH_NEEDS_WEAK_PER_CPU in the kernel code with MODULE_NEEDS_WEAK_PER_CPU,MODULE_NEEDS_WEAK_PER_CPU might be a more accurate description,because it was only needed for modules. Then,when defining the percpu variable _shared_alloc_tag,wrap it with the CONFIG_ARCH_NEEDS_WEAK_PER_CPU condition. The following version can be regarded as the most original version: https://lore.kernel.org/all/20250529073537.563107-1-hao.ge@linux.dev/ But unfortunately,it caused build errors on s390. Based on Suren's guidance and suggestions, I've refined it into this patch series. Many thanks to Suren for his patient instruction. Verify: 1. On Arm64: nm vmlinux | grep "_shared_alloc_tag",no output is returned. 2. On S390: Compile tested. nm vmlinux | grep "_shared_alloc_tag" 00000000015605b4 r __crc__shared_alloc_tag 0000000001585fef r __kstrtab__shared_alloc_tag 0000000001586897 r __kstrtabns__shared_alloc_tag 00000000014f6548 r __ksymtab__shared_alloc_tag 0000000001a8fa28 D _shared_alloc_tag nm net/ceph/libceph.ko | grep "_shared" U _shared_alloc_tag 3. On alpha Compile tested. nm vmlinux | grep "_shared_alloc_tag" fffffc0000b080fa r __kstrtab__shared_alloc_tag fffffc0000b07ee7 r __kstrtabns__shared_alloc_tag fffffc0000adee98 r __ksymtab__shared_alloc_tag fffffc0000b83d38 D _shared_alloc_tag nm crypto/cryptomgr.ko | grep "_share" U _shared_alloc_tag v2: Heiko pointed out that when defining MODULE_NEEDS_WEAK_PER_CPU, the CONFIG_ARCH_NEEDS_WEAK_PER_CPU condition in the v1 version should be removed,as it is always true for s390 and alpha architectures.And He also pointed out that patches 2-4 need to be merged into one patch. Modify the code according to the suggestions and update the corresponding commit message. Hao Ge (3): mm/Kconfig: add ARCH_NEEDS_WEAK_PER_CPU Option and enable it for s390/alpha mm: replace ARCH_NEEDS_WEAK_PER_CPU with MODULE_NEEDS_WEAK_PER_CPU mm/alloc_tag: add the CONFIG_ARCH_NEEDS_WEAK_PER_CPU macro when statically defining the percpu variable _shared_alloc_tag arch/alpha/Kconfig | 1 + arch/alpha/include/asm/percpu.h | 2 +- arch/s390/Kconfig | 1 + arch/s390/include/asm/percpu.h | 2 +- include/linux/alloc_tag.h | 6 +++--- include/linux/percpu-defs.h | 4 ++-- lib/alloc_tag.c | 2 ++ mm/Kconfig | 4 ++++ 8 files changed, 15 insertions(+), 7 deletions(-) -- 2.25.1