From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f53.google.com (mail-ej1-f53.google.com [209.85.218.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 33732346AC1 for ; Thu, 22 Jan 2026 14:00:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769090440; cv=none; b=JhvgSKG3OlrydE0d1vericjNY0FHqwwD/JkIHSsPFFA91cGuD1et4q7y2fOwQjDOM6Byx3l6wncvCL4EKcTjKZf0lDuHEmqv2euz7NFr4D5GQrdLY6MtjyHA5kBEpitfYiZT0SqWLdPcxspu34U720eVAEUSYGssdVOuY5Srif0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769090440; c=relaxed/simple; bh=AHSBEaRYfStLiqJd2Yrr0EQ+tzb5DiwinzVPHKX4hIs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=TRccx2mpHHAr8bwESTaHYGMzHv1gDF2xYpHG13Ki4k0+e07iWD/Ukl81jPr5DmqOQ7lQTU4B32FKZjdg9ma9n73T/4vOzDu9X6P1pmK3vzXLdqoRVmbm7u7eHmgWaqNE1JaixLsEN5zhrY8Eii4SxEri42G0PwJKUUYjZ9X1n30= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=mE3JzZyS; arc=none smtp.client-ip=209.85.218.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="mE3JzZyS" Received: by mail-ej1-f53.google.com with SMTP id a640c23a62f3a-b8837152db5so89784666b.0 for ; Thu, 22 Jan 2026 06:00:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1769090436; x=1769695236; darn=vger.kernel.org; h=user-agent:in-reply-to:content-disposition:mime-version:references :reply-to:message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=KXXllTpn+4j3DQ+o0FpmjiZEdWUg34VA5GPm+3TDwac=; b=mE3JzZySbsZNFXrazHRmfkLgXK1G6CICo/45BaSEMmri8qoPvELmkqlJUJuLq8r/cR BZuBE98d600tezPM1Ev3Lv6/wgj1maHQPUX5UMH0X7Bb1TL3sUzOm4dc6Ly1PPaTjaqs hDxR1qZKtGXBH67ziEpREgFLFgUdSeobUOgLHgZlfBxr0178fS+J4nD8OTVboWYl3pQt VfUZvZP7nVL41fRWgaHUJ4aLvHkvxOcT8JiNj8YivRx/Teoe0yOHaPjpxbMoqspGXGs4 vz+mawD5KrfuWoRGegQ0STZROYkcYTyB9Mb6z3UbWWha+b7zhPD0i037Q32eJSQYTC72 KJtw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769090436; x=1769695236; h=user-agent:in-reply-to:content-disposition:mime-version:references :reply-to:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=KXXllTpn+4j3DQ+o0FpmjiZEdWUg34VA5GPm+3TDwac=; b=FQFf3ryfvt+1y+tpsGmjBWfu32bZFvAtRDgkDs6VZCXEyfMeAp7cT/SGkjCLDHtefG nYIUVPEU0EpV29QC9zl8us7kNgyHt/q1e/VMRAVVLKq1Zk5ArIdHn5Pi1/4msqLWrPMM 4imVmLrEuLcmR3BZlyor7X6BAeZL3ffJc/VkyiAMAeTdKKsVi+nNFZX1VGD276muZfW8 XAJunhr2oQdvI8Q61cEicKaK3kThKXTg+CInwKjWbC8dkDAn0Go009NF+4bKqjHo+W6e 7WYe/cJvj4YNKl/Xbzb6I/pU0I5fTingiORcsMdfpfQmkTLKh+iNHjPsLmuKlPiVgKK0 WmuA== X-Forwarded-Encrypted: i=1; AJvYcCX0QHDfHDa/WwWUseI5rvxtqyuDbxbpT0hGUIGFOzptnpyv6NTRTz+hkMPpvNpdoijaZYy3vQyi3O5m@vger.kernel.org X-Gm-Message-State: AOJu0Yx88mI3vszH0hM9Y0AHE4napyCBid987ckD0dAiirgfWWM1Xh0I HP9G7KagUuWFPp78sRSnsXyi0JawngdH4uqm/HebRn7+3DwA2WBZwJT3 X-Gm-Gg: AZuq6aJi/QCFlqUqXJ5poAuVOixg78piTltE+wQ9MPV5hv31ch/7Q/JDQXNO7mrmtWb L6Ybmw4tQr3yFFhZ9VInj6VqXWD3XcTajrwCXBVpoEAyWtFns9MKvJHOULpjmDbLTfXT56Kob4j av6qQoe+MLPJZ2ZcyBv7wOGWfv9VEGYUSbJLC/8Pm+ejA4x62RyJo6Y+owbF6OAl15JLoTy1bNT d/1i+0EuwpcIRmS6yLsQc5dUyYsExAlgK1uUtE6WZ2rbAD8Wz178WqFE85TG9hFvbB3zP8iIkJR XcLc6uj4LY6fbOqZhPxj+qvDdFz00zDP4n5u2HfMyaiaZenU8fQG/oDGx1j6ekiFcf5GSf2XJO9 eyFdZmhG3wyoe0HiRYGcLpd73TCo0Z8MKR89TjbfoHwWvfKa55F8PZosfjsok/QKqYfoYwOuXZ8 iajTUbrIM7sg== X-Received: by 2002:a17:907:84e:b0:b87:33f3:6042 with SMTP id a640c23a62f3a-b8792d3be6dmr1826205366b.9.1769090435585; Thu, 22 Jan 2026 06:00:35 -0800 (PST) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b884006d3bbsm68748466b.32.2026.01.22.06.00.34 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Thu, 22 Jan 2026 06:00:35 -0800 (PST) Date: Thu, 22 Jan 2026 14:00:34 +0000 From: Wei Yang To: "David Hildenbrand (Red Hat)" Cc: Wei Yang , Qi Zheng , will@kernel.org, aneesh.kumar@kernel.org, npiggin@gmail.com, peterz@infradead.org, dev.jain@arm.com, akpm@linux-foundation.org, ioworker0@gmail.com, linmag7@gmail.com, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-alpha@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-um@lists.infradead.org, Qi Zheng Subject: Re: [PATCH v3 7/7] mm: make PT_RECLAIM depends on MMU_GATHER_RCU_TABLE_FREE Message-ID: <20260122140034.ymigrfppzwvmcjkr@master> Reply-To: Wei Yang References: <20251231094243.zmjs7kgflm7q6k73@master> <20260101020715.45wqnjgcklvjcth3@master> Precedence: bulk X-Mailing-List: linux-arch@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) On Mon, Jan 19, 2026 at 11:18:52AM +0100, David Hildenbrand (Red Hat) wrote: >On 1/1/26 03:07, Wei Yang wrote: >> On Wed, Dec 31, 2025 at 05:52:57PM +0800, Qi Zheng wrote: >> > >> > >> > On 12/31/25 5:42 PM, Wei Yang wrote: >> > > On Wed, Dec 17, 2025 at 05:45:48PM +0800, Qi Zheng wrote: >> > > > From: Qi Zheng >> > > > >> > > > The PT_RECLAIM can work on all architectures that support >> > > > MMU_GATHER_RCU_TABLE_FREE, so make PT_RECLAIM depends on >> > > > MMU_GATHER_RCU_TABLE_FREE. >> > > > >> > > > BTW, change PT_RECLAIM to be enabled by default, since nobody should want >> > > > to turn it off. >> > > > >> > > > Signed-off-by: Qi Zheng >> > > > --- >> > > > arch/x86/Kconfig | 1 - >> > > > mm/Kconfig | 9 ++------- >> > > > 2 files changed, 2 insertions(+), 8 deletions(-) >> > > > >> > > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig >> > > > index 80527299f859a..0d22da56a71b0 100644 >> > > > --- a/arch/x86/Kconfig >> > > > +++ b/arch/x86/Kconfig >> > > > @@ -331,7 +331,6 @@ config X86 >> > > > select FUNCTION_ALIGNMENT_4B >> > > > imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI >> > > > select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE >> > > > - select ARCH_SUPPORTS_PT_RECLAIM if X86_64 >> > > > select ARCH_SUPPORTS_SCHED_SMT if SMP >> > > > select SCHED_SMT if SMP >> > > > select ARCH_SUPPORTS_SCHED_CLUSTER if SMP >> > > > diff --git a/mm/Kconfig b/mm/Kconfig >> > > > index bd0ea5454af82..fc00b429b7129 100644 >> > > > --- a/mm/Kconfig >> > > > +++ b/mm/Kconfig >> > > > @@ -1447,14 +1447,9 @@ config ARCH_HAS_USER_SHADOW_STACK >> > > > The architecture has hardware support for userspace shadow call >> > > > stacks (eg, x86 CET, arm64 GCS or RISC-V Zicfiss). >> > > > >> > > > -config ARCH_SUPPORTS_PT_RECLAIM >> > > > - def_bool n >> > > > - >> > > > config PT_RECLAIM >> > > > - bool "reclaim empty user page table pages" >> > > > - default y >> > > > - depends on ARCH_SUPPORTS_PT_RECLAIM && MMU && SMP >> > > > - select MMU_GATHER_RCU_TABLE_FREE >> > > > + def_bool y >> > > > + depends on MMU_GATHER_RCU_TABLE_FREE >> > > > help >> > > > Try to reclaim empty user page table pages in paths other than munmap >> > > > and exit_mmap path. >> > > >> > > Hi, Qi >> > > >> > > I am new to PT_RECLAIM, when reading related code I got one question. >> > > >> > > Before this patch, we could have this config combination: >> > > >> > > CONFIG_MMU_GATHER_RCU_TABLE_FREE & !CONFIG_PT_RECLAIM >> > > >> > > This means tlb_remove_table_free() is rcu version while tlb_remove_table_one() >> > > is semi rcu version. >> > > >> > > I am curious could we use rcu version tlb_remove_table_one() for this case? >> > > Use rcu version tlb_remove_table_one() if CONFIG_MMU_GATHER_RCU_TABLE_FREE. Is >> > > there some limitation here? >> > >> > I think there's no problem. The rcu version can also ensure that the >> > fast GUP works well. >> > >> >> Thanks for your quick response :-) >> >> And Happy New Year >> >> So my little suggestion is move the definition of __tlb_remove_table_one() >> under CONFIG_MMU_GATHER_RCU_TABLE_FREE. Do you thinks this would be more >> clear? > > >Do you mean > >diff --git a/mm/mmu_gather.c b/mm/mmu_gather.c >index 2faa23d7f8d42..6aeba4bae68d2 100644 >--- a/mm/mmu_gather.c >+++ b/mm/mmu_gather.c >@@ -319,7 +319,7 @@ static inline void tlb_table_invalidate(struct mmu_gather >*tlb) > } > } > >-#ifdef CONFIG_PT_RECLAIM >+#ifdef CONFIG_MMU_GATHER_RCU_TABLE_FREE > static inline void __tlb_remove_table_one_rcu(struct rcu_head *head) > { > struct ptdesc *ptdesc; > >? Sorry for the late reply. Yes, and maybe we can move the definition to the #ifdef CONFIG_MMU_GATHER_RCU_TABLE_FREE code block above, then to be next to tlb_remove_table_free(). So that we always have rcu version when CONFIG_MMU_GATHER_RCU_TABLE_FREE. > >-- >Cheers > >David -- Wei Yang Help you, Help me