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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B5E40D77898 for ; Sat, 24 Jan 2026 01:45:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0DF3D6B0089; Fri, 23 Jan 2026 20:45:58 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0BD206B0576; Fri, 23 Jan 2026 20:45:58 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F2BD86B057A; Fri, 23 Jan 2026 20:45:57 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id D1DBA6B0089 for ; Fri, 23 Jan 2026 20:45:57 -0500 (EST) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 8EB02B5445 for ; Sat, 24 Jan 2026 01:45:57 +0000 (UTC) X-FDA: 84365166354.17.A255E46 Received: from mail-ej1-f47.google.com (mail-ej1-f47.google.com [209.85.218.47]) by imf07.hostedemail.com (Postfix) with ESMTP id 8F32D40005 for ; Sat, 24 Jan 2026 01:45:55 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=FVB9Khcv; spf=pass (imf07.hostedemail.com: domain of richard.weiyang@gmail.com designates 209.85.218.47 as permitted sender) smtp.mailfrom=richard.weiyang@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1769219155; h=from:from:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=ZXp0QJyrLLUrmQyXAB/60kXaLRgyX8FN8f699HysLTo=; b=sjLX+Trf1CMEP2yKB1OxSxmnSrXjH0PkNrMICgltSmEoU8m3sZvPH82GtR5Q6P0gnqr6iv 4N2Gpq8y70Be318zOLEElvV1/X/OwXAVfpeC/XDHjNaiA5w/iv+N13uXJ1cgXExw4TkTxK 2SD7B+tziuygYIhiyQL3Grd7BGR975E= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=FVB9Khcv; spf=pass (imf07.hostedemail.com: domain of richard.weiyang@gmail.com designates 209.85.218.47 as permitted sender) smtp.mailfrom=richard.weiyang@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1769219155; a=rsa-sha256; cv=none; b=oPI/32STgWB0llgc1XYSLF27GnrGp3D4ZUz/g9pAPD5WR6Zs0YWMVvSlN9T6ehdJDMTDUt kazPuwOo6xpQM2duv6Q+gowUNuIt3WJ+WGscjuXPDZ16uv6n7UQth2ZSu3jVehC6uwnkrW P1elAgvYCgL7LuMK0okKdupUpH2Z2M0= Received: by mail-ej1-f47.google.com with SMTP id a640c23a62f3a-b8710c9cddbso364652566b.2 for ; Fri, 23 Jan 2026 17:45:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1769219154; x=1769823954; darn=kvack.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=ZXp0QJyrLLUrmQyXAB/60kXaLRgyX8FN8f699HysLTo=; b=FVB9Khcv6emEgyKo2Z16BAc/3zoQRweAqufDsutoJ6chl1H3R51zLsqWI8DUhE9RqV 0PqkWiFfyWQrQeiu33F8hmCz0S1CFYmglLV3ZiAp1SnqvzHdtLNrSs6XluDj7HuW/WC1 QbUOpTcXP+12v8ayPKKtof18uzmROUBaAYLpDZLpWMg4O7HEMiUrijjm4OjDfKILushY XcAktWDC99K1HMcoQfjFiev2Dg3hetzhfUMqCSjuSpd1vY8ZY5EeyxMhZzTCI0k9GaPA 1kT22iOMlWambTfNJGfiYbXmcuVSQJ2DbULGWf4k8DdpjBwMprfo30WcXuhohaMlqMDY SsFg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769219154; x=1769823954; 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=ZXp0QJyrLLUrmQyXAB/60kXaLRgyX8FN8f699HysLTo=; b=bpWFy/VTMBYo0HLz0fiSQmJ/9zBY53z9x5eeyHTgNK6h3IjSXiO4pTU/yV0PmcLgHW 6O2D2EEJfIU8AADrtpJKgu8SGT5AEBZBJn6eNBDxJoCIE72v9ye3t0DytQ5sjM+ohP6r 1kMKz18xx4mYxYZpyl3AuEKr1sa6KzB1VMTOIeCvZtb1YebZwF7d6/uw4w/rAROWpR0C vmaipWVIj9fcDKVqr4GvvYozXkcasLtBKP8dDt8EZKrBqHCRs0Nb53QQGerlLT8KDrBl clacKoofjGO02k9EE5IRyQtDGhfTQq61Lxb7QLN3kTN81SZswxKZt6rSEjzTIqrxv8WQ jASA== X-Forwarded-Encrypted: i=1; AJvYcCX1oNkUnT6qA3rvoctdWG9Fr1cx2hAni7d15nbKICx/vcc45ShZCrT8OCmWLcC62Aai12a9Dl66+w==@kvack.org X-Gm-Message-State: AOJu0YxdXZQJ5fSyztjRzVjmGniI0x4GdhW7jsdov2CcI1uNMcwbm121 gR7fnZ5Q4m8/hzeiFTLrk9AEL8wZeqewykCnoK1jQkc92WKaXNln5zQa X-Gm-Gg: AZuq6aL1x8xEyMKrxCL/6TIP4vY9TAb/KHIV8YZr8xQkEbxFDH8kE9arkfPkylX3dnB CB0zaFSbRYODaIL/8GAvh45EBC/sg6VPrcYWNqBSG8frfcBe1wgQbd89jd52X2GmINXQrKOPvyI sN+dcrrk97ZzD2xtuEoXBJW2+kcDsP43pVAARum9L7+mWx5skRJUX7uBwkFaIEWRPFMyCQfCIo+ 57w1p3oJ+22nfPaIJaRktuE6PdwIf7UuO3KsktrU5jbv4LdgMF19qNmlAhrS2bkZLBbSpkYveOK cm/TLdG2BfEabKD8t+eUS7DaNKKqCkoi41MxULP5rPRVHH89D+ehf7M+hRJ5NY4jkEcRZgo1v8h 4inNkFd2mkAbhkHSfx+s75GgFurxXpT+DOSSiljQdHzdBAZmAJsOapTNpDkY9gfpMdVdJ2RXh7s Sxib446iiS/g== X-Received: by 2002:a17:907:3f03:b0:b7a:18ba:a63 with SMTP id a640c23a62f3a-b885ac2bd1dmr330014466b.19.1769219153636; Fri, 23 Jan 2026 17:45:53 -0800 (PST) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b886a249e69sm125246466b.6.2026.01.23.17.45.52 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Fri, 23 Jan 2026 17:45:52 -0800 (PST) Date: Sat, 24 Jan 2026 01:45:52 +0000 From: Wei Yang To: Qi Zheng Cc: Wei Yang , "David Hildenbrand (Red Hat)" , 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: <20260124014552.um257bwrhwjktdca@master> Reply-To: Wei Yang References: <20251231094243.zmjs7kgflm7q6k73@master> <20260101020715.45wqnjgcklvjcth3@master> <20260122140034.ymigrfppzwvmcjkr@master> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) X-Stat-Signature: 56enn6efsd66om7toj7o6mkk7ot5cei5 X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 8F32D40005 X-HE-Tag: 1769219155-85745 X-HE-Meta: U2FsdGVkX19iaed/6+3d9vLeYTTQTWw8nmxXWoV7uHt1lRx9FTtnk/YJKlJtIqO2+15w1UvHIcQFf7in+K18PI9IIpNtRr0GeXItgBA5v1J2w8GBl7t0MH2QizlWR3wI75+XWKPN9b3RO820yvN2JnL+U4k1GZMPT34xF4mizK4i4Tg6udkAiJ/KhA5UhFM9d4Ex6POtdd3KczlOWUU8RBqe0dhAa7EbLi5eBNVBVJZUT6EgfQeT8MH9bM+rMMmbmj0sPafSVpLmVHcrd2xX0IT831SmySCZ7/In+ccEBKg5ugP9ePlR+rJBj4XTp6O456H9i1cZJ02DQDWWzSP8d5Ou1dvJCrkiluYLdN6jyUxY1kXpJGynWHb3FbA/GLnGtMyob2xkSc/GQ/Bsr/6oJN87i54eKxsl5P+cErHuE7s19Jng1tBvoDw2Xbhl44vx3QlOJ3rL5vNCK2eKonACmxZ0Mmr7zug81kYb60UFdooZohO28NFrgkZBd9NrcCddCu43w7l8i1wvDArNbBVBSSA8ZoY8ZGznO1fegUSbzRM1A6cMGHwbio5RxxSUZJRnju2+vsLt1O2BKcmFNm9Iv0z9opjcm+5LGqBPFdrmTjPvbQfneWZujWrhXYhNrnFDodcYO/OArOdQEc8tEWV3P1u35+D/2GssJnNdNtXpRV7FHnLroESK1JOR31S2b3NAXBwCs6sQqS7ze6/QV+AOWNM8oyRoM2nl4CMvvSx/Eq5wab8/7Ttnd+oTUmX/TSCo+eZeJET/s9dv9hNHOhy9JoFI9PPbpKLi4Vzcr78QTxhu6qn8IMwcjypN5sGdVab+j8gfO1w/ZlFj43mfbAzVNPlEwfzIGm+jbgraLbwx0ASYjumi5NhB8Shn1uR0icBXhhWLP1g2tWRx2dc+EXkGlP3OuFizLNHYe+6UPWGVJguHbUW3xo19jC34MjrIBPwOrxbG4BHJAPCBCdlTXlI QefqcKoj 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 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: On Fri, Jan 23, 2026 at 11:21:50AM +0800, Qi Zheng wrote: > > >On 1/22/26 10:00 PM, Wei Yang wrote: >> 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. > >LGTM, could you help submit an official patch? > Sure. Since this is trivial cleanup, I will post it till next merge window. >Thanks, >Qi > >> >> > >> > -- >> > Cheers >> > >> > David >> -- Wei Yang Help you, Help me