From nobody Fri Oct 10 04:00:27 2025 Received: from out-171.mta1.migadu.com (out-171.mta1.migadu.com [95.215.58.171]) (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 03BE819D06A for ; Mon, 16 Jun 2025 02:30:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.171 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750041021; cv=none; b=Yv9QWyzGYXgE9nmj9kpcvYGsxynMABmFHm+xpF9n+4emlIH9Id1bFqz+XeQHZB2ePb2aJeJPFCzQQhbXX820ru4Zze0fwZHZ/B3RjSMo45waVC/1O/e/vVMEpHzuWG952kKzPmK+1MeTKut+WtiAZp1SqI9VX4dMAQST9Yl/+Vk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750041021; c=relaxed/simple; bh=DLg7jR/HwT4NCqG6p+WfFEeT2droSNr6aBN+7EbQuIE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=jhEIFC8teGGzViE/IutGBb1dtIU1xPyXceGf9SCd+amzDFcRxkNbG5uhfKohCe27WOY2sbFFDiqJ6HP14i3bZqy2oCQYsREAR3S1Zh/7S7b+P5tBroaqSi3uy/0Kh9cq7y5oyQauM/NO9FAtkE4J7b9dxzlXsRyF01grHALV2TY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=G1nsNB40; arc=none smtp.client-ip=95.215.58.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="G1nsNB40" 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=1750041016; 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: in-reply-to:in-reply-to:references:references; bh=TwaFPyIkk+e4dx1cWe+AhOCnypnekR9FeQe3heGaETY=; b=G1nsNB403+jLLhmsMsa83nMOPV15GspnvXLjv/x1jEbGPHiXpQ5aonlDOWgJ5wOgolDj3X odcqhWwE/bLnF71FVMAxtsVuVQovfQsMd1PcpRs27GGlEETJacLNTFJ+Bv/MVsE/rWsCE+ 9ugUOwqUkn5vVH5RM727QiSIbuyyD44= 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 v3 1/2] mm: Optimize the ARCH_NEEDS_WEAK_PER_CPU logic for s390/alpha architectures Date: Mon, 16 Jun 2025 10:29:17 +0800 Message-Id: <57e110be6d8387e403b4ef1f3b10714c36afbb51.1750040317.git.gehao@kylinos.cn> In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" 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. 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. Therefore, this patch does the following things: Add the ARCH_NEEDS_WEAK_PER_CPU option to the mm Kconfig file and enable it for the s390 and alpha architectures. And replace all instances of ARCH_NEEDS_WEAK_PER_CPU in the kernel code with MODULE_NEEDS_WEAK_PER_CPU. Suggested-by: Suren Baghdasaryan Signed-off-by: Hao Ge --- 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 ++-- mm/Kconfig | 4 ++++ 7 files changed, 13 insertions(+), 7 deletions(-) diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig index 109a4cddcd13..ce9bc842e384 100644 --- a/arch/alpha/Kconfig +++ b/arch/alpha/Kconfig @@ -7,6 +7,7 @@ config ALPHA select ARCH_HAS_DMA_OPS if PCI select ARCH_MIGHT_HAVE_PC_PARPORT select ARCH_MIGHT_HAVE_PC_SERIO + select ARCH_NEEDS_WEAK_PER_CPU select ARCH_NO_PREEMPT select ARCH_NO_SG_CHAIN select ARCH_USE_CMPXCHG_LOCKREF diff --git a/arch/alpha/include/asm/percpu.h b/arch/alpha/include/asm/percp= u.h index 6923249f2d49..b164d3720e9e 100644 --- a/arch/alpha/include/asm/percpu.h +++ b/arch/alpha/include/asm/percpu.h @@ -11,7 +11,7 @@ * Always use weak definitions for percpu variables in modules. */ #if defined(MODULE) && defined(CONFIG_SMP) -#define ARCH_NEEDS_WEAK_PER_CPU +#define MODULE_NEEDS_WEAK_PER_CPU #endif =20 #include diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 0c16dc443e2f..716031d22346 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -132,6 +132,7 @@ config S390 select ARCH_INLINE_WRITE_UNLOCK_IRQ select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE + select ARCH_NEEDS_WEAK_PER_CPU select ARCH_STACKWALK select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_DEBUG_PAGEALLOC diff --git a/arch/s390/include/asm/percpu.h b/arch/s390/include/asm/percpu.h index 84f6b8357b45..0afc7ce9c26f 100644 --- a/arch/s390/include/asm/percpu.h +++ b/arch/s390/include/asm/percpu.h @@ -18,7 +18,7 @@ * generate external references. */ #if defined(MODULE) -#define ARCH_NEEDS_WEAK_PER_CPU +#define MODULE_NEEDS_WEAK_PER_CPU #endif =20 /* diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h index 8f7931eb7d16..f349cca0ebed 100644 --- a/include/linux/alloc_tag.h +++ b/include/linux/alloc_tag.h @@ -88,7 +88,7 @@ static inline struct alloc_tag *ct_to_alloc_tag(struct co= detag *ct) return container_of(ct, struct alloc_tag, ct); } =20 -#ifdef ARCH_NEEDS_WEAK_PER_CPU +#ifdef MODULE_NEEDS_WEAK_PER_CPU /* * When percpu variables are required to be defined as weak, static percpu * variables can't be used inside a function (see comments for DECLARE_PER= _CPU_SECTION). @@ -102,7 +102,7 @@ DECLARE_PER_CPU(struct alloc_tag_counters, _shared_allo= c_tag); .ct =3D CODE_TAG_INIT, \ .counters =3D &_shared_alloc_tag }; =20 -#else /* ARCH_NEEDS_WEAK_PER_CPU */ +#else /* MODULE_NEEDS_WEAK_PER_CPU */ =20 #ifdef MODULE =20 @@ -123,7 +123,7 @@ DECLARE_PER_CPU(struct alloc_tag_counters, _shared_allo= c_tag); =20 #endif /* MODULE */ =20 -#endif /* ARCH_NEEDS_WEAK_PER_CPU */ +#endif /* MODULE_NEEDS_WEAK_PER_CPU */ =20 DECLARE_STATIC_KEY_MAYBE(CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT, mem_alloc_profiling_key); diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h index 0aeb0e276a3e..b4ecfc3a7b2b 100644 --- a/include/linux/percpu-defs.h +++ b/include/linux/percpu-defs.h @@ -64,13 +64,13 @@ * 2. Static percpu variables cannot be defined inside a function. * * Archs which need weak percpu definitions should define - * ARCH_NEEDS_WEAK_PER_CPU in asm/percpu.h when necessary. + * MODULE_NEEDS_WEAK_PER_CPU in asm/percpu.h when necessary. * * To ensure that the generic code observes the above two * restrictions, if CONFIG_DEBUG_FORCE_WEAK_PER_CPU is set weak * definition is used for all cases. */ -#if defined(ARCH_NEEDS_WEAK_PER_CPU) || defined(CONFIG_DEBUG_FORCE_WEAK_PE= R_CPU) +#if defined(MODULE_NEEDS_WEAK_PER_CPU) || defined(CONFIG_DEBUG_FORCE_WEAK_= PER_CPU) /* * __pcpu_scope_* dummy variable is used to enforce scope. It * receives the static modifier when it's used in front of diff --git a/mm/Kconfig b/mm/Kconfig index e113f713b493..2f55cc95cfcb 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -929,6 +929,10 @@ config ARCH_SUPPORTS_PUD_PFNMAP def_bool y depends on ARCH_SUPPORTS_HUGE_PFNMAP && HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD =20 +# s390 and alpha should be enabled,see comments for DECLARE_PER_CPU_SECTION +config ARCH_NEEDS_WEAK_PER_CPU + bool + # # UP and nommu archs use km based percpu allocator # --=20 2.25.1 From nobody Fri Oct 10 04:00:27 2025 Received: from out-187.mta1.migadu.com (out-187.mta1.migadu.com [95.215.58.187]) (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 84373296153 for ; Mon, 16 Jun 2025 02:30:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.187 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750041028; cv=none; b=rCfk4xTaQBzy6stDQ3tCCDd4SaHhmHzsrRnlL9V/3hnBJv0U65iIFaxbkFD2p8UksOymN+pug2r2/94qMraCjw2h9qhJsQQppUfl7QmQ4kMuM65zeE30fWYZIznlxwuPPC2Q431+r0fiwZAQ1cViZgu5mUneTd179XSP6BZnaGU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750041028; c=relaxed/simple; bh=K6Lvk3lCdv4M+F3hTNjTrtGNVvzF0n8odBOG6Q3Tp4k=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=BqYd0wmqvbb5Vgr8u2wpi1xhbKRjmIWrOG1idqpq0aqGEjma40piSL6SIH8I+cl1Bl+hSA1Z89A3lygfkvec5jrsZvaS5SE/slRtttcAB8s72m1Ysv+j8yKf+LvXTRE321L8vGqQXPBN4daSGzRdQMZga4JfOQk88SyMc8G9rBQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=ovwn9yIL; arc=none smtp.client-ip=95.215.58.187 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="ovwn9yIL" 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=1750041024; 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: in-reply-to:in-reply-to:references:references; bh=hz18ocd/uSYiTes8KSvGTUaH79rqlEUDMw44khNO0b8=; b=ovwn9yILg7Ld/EV2cpX+yCktmX9NPFhFTkL7UBJuwOWxR6IpOsktL/W+xgQkSTJCcKQh9v JI01sD8DujrTD/KOB2P6oLNChagB8pDmUAfvKDzDcEuKcs4I/XzZozZid4bpFpU+e1NqTQ n2/IvX36dhEGHi81Fn9cIbXZtgGVh0o= 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 v3 2/2] mm/alloc_tag: add the CONFIG_ARCH_NEEDS_WEAK_PER_CPU macro when statically defining the percpu variable _shared_alloc_tag Date: Mon, 16 Jun 2025 10:29:18 +0800 Message-Id: In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" From: Hao Ge Given the introduction of the CONFIG_ARCH_NEEDS_WEAK_PER_CPU macro, we can now conditionally define the perpcu variable _shared_alloc_tag based on its value. This allows architectures(such as s390/alpha) that require weak definitions for percpu variables in modules to include the definition,while others can omit it via compile-time exclusion. Suggested-by: Suren Baghdasaryan Signed-off-by: Hao Ge --- lib/alloc_tag.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c index c7f602fa7b23..14fd66f26e42 100644 --- a/lib/alloc_tag.c +++ b/lib/alloc_tag.c @@ -24,8 +24,10 @@ static bool mem_profiling_support; =20 static struct codetag_type *alloc_tag_cttype; =20 +#ifdef CONFIG_ARCH_NEEDS_WEAK_PER_CPU DEFINE_PER_CPU(struct alloc_tag_counters, _shared_alloc_tag); EXPORT_SYMBOL(_shared_alloc_tag); +#endif =20 DEFINE_STATIC_KEY_MAYBE(CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT, mem_alloc_profiling_key); --=20 2.25.1