From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.15]) (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 1B15C2A1BF; Tue, 14 Jul 2026 15:09:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784041771; cv=none; b=s1ZmeKUMuMO9wrDXfOM51NgnMPFSxLKynhaNKrWBBFgMmOffr929mUZaNTqRQv9F0+E2oOAC2lsuesNhlscoC7q1x1oNfPIFD5+GFFK9ZSXQg6Lf9s5FpfeWLJ6DJt2AY2e1TKEb1/XBYvtGbbDDcED1JPWs4XpIyRKBXwEA5aY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784041771; c=relaxed/simple; bh=SHzp4jQz8eCvIdV8ejmgEgUpbyhbt03HpKcF+s/pm00=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=jqullOLY41anbk6+XhiclBbZtTQDWZYKjvA/gUcx94Hg3hMINotCrg+wBDmKeU3CavIfohibP00pDm8hCbJOORexUez6ef62WQYkk7Uh0uXIF9yH9pJvTQDqTGyz0enjy52ddDCWpK1tzsU1YaxCrP2JMt4kG2fzHljb0N68hYU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Zu45SdRD; arc=none smtp.client-ip=198.175.65.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Zu45SdRD" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1784041770; x=1815577770; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=SHzp4jQz8eCvIdV8ejmgEgUpbyhbt03HpKcF+s/pm00=; b=Zu45SdRDUpTedchym1+CAPSKVM3OLxjH46haJbX64zEWibFBVyGX5Hyu irekaMSiTwRkBKD2bjw6BNloegglXhfKpw6twcKT5RfVXP9Grd4VvZRPZ GHvkEmtqWfW+G58L781tlaZQXx+3dTAIriSwcRbdKPBG81nA05KK63tO5 JPTjBEGJ0KdxZ+u91bkOibpnzkFKxC3T9R3VQkxFiK6kU6iIswLtCer5R w9Kp7hxavztIYEeLTzPH4+PhRAC/tt+/m+/vBqi8I3DKzJaDvY3SIHQkH kj2AQcddH3MZgpBSrB2At3+vZX9aWoEJUsQZToOT2m7RYvxzEQxRtKISr A==; X-CSE-ConnectionGUID: uZQ/FPi9T4uwTXGJbuxl3w== X-CSE-MsgGUID: ZybouAbVRF2Di5Jz6UIexA== X-IronPort-AV: E=McAfee;i="6800,10657,11846"; a="88344343" X-IronPort-AV: E=Sophos;i="6.25,164,1779174000"; d="scan'208";a="88344343" Received: from orviesa005.jf.intel.com ([10.64.159.145]) by orvoesa107.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Jul 2026 08:09:28 -0700 X-CSE-ConnectionGUID: b6dfcSKcQJiv0EAhPLDFYA== X-CSE-MsgGUID: 47aAtZOESKmlSCqMXmHYjw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,164,1779174000"; d="scan'208";a="260186915" Received: from aschende-mobl.amr.corp.intel.com (HELO [10.125.108.120]) ([10.125.108.120]) by orviesa005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Jul 2026 08:09:12 -0700 Message-ID: Date: Tue, 14 Jul 2026 08:09:15 -0700 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 12/22] x86/mm: use mm_is_kernel() for kernel mm checks To: Kevin Brodsky , linux-mm@kvack.org Cc: Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Pasha Tatashin , Russell King , Catalin Marinas , Will Deacon , Ryan Roberts , linux-arm-kernel@lists.infradead.org, Huacai Chen , loongarch@lists.linux.dev, "James E.J. Bottomley" , Helge Deller , linux-parisc@vger.kernel.org, Madhavan Srinivasan , Michael Ellerman , linuxppc-dev@lists.ozlabs.org, Paul Walmsley , Palmer Dabbelt , Albert Ou , linux-riscv@lists.infradead.org, Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Gerald Schaefer , linux-s390@vger.kernel.org, "David S. Miller" , Andreas Larsson , sparclinux@vger.kernel.org, Richard Weinberger , Anton Ivanov , Johannes Berg , linux-um@lists.infradead.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Ning Sun , x86@kernel.org, tboot-devel@lists.sourceforge.net, Ard Biesheuvel , Ilias Apalodimas , linux-efi@vger.kernel.org, Vishal Moola , Alistair Popple , "Matthew Wilcox (Oracle)" , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org References: <20260714-remove_pgtable_cdtor-v1-0-44be8a7685d7@arm.com> <20260714-remove_pgtable_cdtor-v1-12-44be8a7685d7@arm.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzUVEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gKEludGVsIFdvcmsgQWRkcmVzcykgPGRhdmUuaGFuc2VuQGludGVs LmNvbT7CwXgEEwECACIFAlQ+9J0CGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEGg1 lTBwyZKwLZUP/0dnbhDc229u2u6WtK1s1cSd9WsflGXGagkR6liJ4um3XCfYWDHvIdkHYC1t MNcVHFBwmQkawxsYvgO8kXT3SaFZe4ISfB4K4CL2qp4JO+nJdlFUbZI7cz/Td9z8nHjMcWYF IQuTsWOLs/LBMTs+ANumibtw6UkiGVD3dfHJAOPNApjVr+M0P/lVmTeP8w0uVcd2syiaU5jB aht9CYATn+ytFGWZnBEEQFnqcibIaOrmoBLu2b3fKJEd8Jp7NHDSIdrvrMjYynmc6sZKUqH2 I1qOevaa8jUg7wlLJAWGfIqnu85kkqrVOkbNbk4TPub7VOqA6qG5GCNEIv6ZY7HLYd/vAkVY E8Plzq/NwLAuOWxvGrOl7OPuwVeR4hBDfcrNb990MFPpjGgACzAZyjdmYoMu8j3/MAEW4P0z F5+EYJAOZ+z212y1pchNNauehORXgjrNKsZwxwKpPY9qb84E3O9KYpwfATsqOoQ6tTgr+1BR CCwP712H+E9U5HJ0iibN/CDZFVPL1bRerHziuwuQuvE0qWg0+0SChFe9oq0KAwEkVs6ZDMB2 P16MieEEQ6StQRlvy2YBv80L1TMl3T90Bo1UUn6ARXEpcbFE0/aORH/jEXcRteb+vuik5UGY 5TsyLYdPur3TXm7XDBdmmyQVJjnJKYK9AQxj95KlXLVO38lczsFNBFRjzmoBEACyAxbvUEhd GDGNg0JhDdezyTdN8C9BFsdxyTLnSH31NRiyp1QtuxvcqGZjb2trDVuCbIzRrgMZLVgo3upr MIOx1CXEgmn23Zhh0EpdVHM8IKx9Z7V0r+rrpRWFE8/wQZngKYVi49PGoZj50ZEifEJ5qn/H Nsp2+Y+bTUjDdgWMATg9DiFMyv8fvoqgNsNyrrZTnSgoLzdxr89FGHZCoSoAK8gfgFHuO54B lI8QOfPDG9WDPJ66HCodjTlBEr/Cwq6GruxS5i2Y33YVqxvFvDa1tUtl+iJ2SWKS9kCai2DR 3BwVONJEYSDQaven/EHMlY1q8Vln3lGPsS11vSUK3QcNJjmrgYxH5KsVsf6PNRj9mp8Z1kIG qjRx08+nnyStWC0gZH6NrYyS9rpqH3j+hA2WcI7De51L4Rv9pFwzp161mvtc6eC/GxaiUGuH BNAVP0PY0fqvIC68p3rLIAW3f97uv4ce2RSQ7LbsPsimOeCo/5vgS6YQsj83E+AipPr09Caj 0hloj+hFoqiticNpmsxdWKoOsV0PftcQvBCCYuhKbZV9s5hjt9qn8CE86A5g5KqDf83Fxqm/ vXKgHNFHE5zgXGZnrmaf6resQzbvJHO0Fb0CcIohzrpPaL3YepcLDoCCgElGMGQjdCcSQ+Ci FCRl0Bvyj1YZUql+ZkptgGjikQARAQABwsFfBBgBAgAJBQJUY85qAhsMAAoJEGg1lTBwyZKw l4IQAIKHs/9po4spZDFyfDjunimEhVHqlUt7ggR1Hsl/tkvTSze8pI1P6dGp2XW6AnH1iayn yRcoyT0ZJ+Zmm4xAH1zqKjWplzqdb/dO28qk0bPso8+1oPO8oDhLm1+tY+cOvufXkBTm+whm +AyNTjaCRt6aSMnA/QHVGSJ8grrTJCoACVNhnXg/R0g90g8iV8Q+IBZyDkG0tBThaDdw1B2l asInUTeb9EiVfL/Zjdg5VWiF9LL7iS+9hTeVdR09vThQ/DhVbCNxVk+DtyBHsjOKifrVsYep WpRGBIAu3bK8eXtyvrw1igWTNs2wazJ71+0z2jMzbclKAyRHKU9JdN6Hkkgr2nPb561yjcB8 sIq1pFXKyO+nKy6SZYxOvHxCcjk2fkw6UmPU6/j/nQlj2lfOAgNVKuDLothIxzi8pndB8Jju KktE5HJqUUMXePkAYIxEQ0mMc8Po7tuXdejgPMwgP7x65xtfEqI0RuzbUioFltsp1jUaRwQZ MTsCeQDdjpgHsj+P2ZDeEKCbma4m6Ez/YWs4+zDm1X8uZDkZcfQlD9NldbKDJEXLIjYWo1PH hYepSffIWPyvBMBTW2W5FRjJ4vLRrJSUoEfJuPQ3vW9Y73foyo/qFoURHO48AinGPZ7PC7TF vUaNOTjKedrqHkaOcqB185ahG2had0xnFsDPlx5y In-Reply-To: <20260714-remove_pgtable_cdtor-v1-12-44be8a7685d7@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/14/26 07:04, Kevin Brodsky wrote: ... > @@ -188,7 +188,7 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct tlb_state_shared, cpu_tlbstate_shared); > #define enter_lazy_tlb enter_lazy_tlb > static __always_inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) > { > - if (this_cpu_read(cpu_tlbstate.loaded_mm) == &init_mm) > + if (mm_is_kernel(this_cpu_read(cpu_tlbstate.loaded_mm))) > return; > > this_cpu_write(cpu_tlbstate_shared.is_lazy, true); This one makes me nervous, especially combined with the efi_mm changes later in the series. init_mm really is special. Before this patch, running on init_mm qualifies as being in lazy tlb mode. After this patch, efi_mm qualifies too. Is that OK? > diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c > index f32facdb3035..91d2a6f2ac5a 100644 > --- a/arch/x86/mm/pgtable.c > +++ b/arch/x86/mm/pgtable.c > @@ -168,7 +168,7 @@ static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[], int count) > bool failed = false; > gfp_t gfp = GFP_PGTABLE_USER; > > - if (mm == &init_mm) > + if (mm_is_kernel(mm)) > gfp &= ~__GFP_ACCOUNT; > gfp &= ~__GFP_HIGHMEM; This hunk is probably fine. > diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c > index 1023acadd8f8..5517cab8ad00 100644 > --- a/arch/x86/mm/tlb.c > +++ b/arch/x86/mm/tlb.c > @@ -594,7 +594,7 @@ void leave_mm(void) > * This needs to happen before any other sanity checks due to > * intel_idle's shenanigans. > */ > - if (loaded_mm == &init_mm) > + if (mm_is_kernel(loaded_mm)) > return; This one is almost *certainly* buggy. The efi_mm stuff uses leave_mm(). In fact, I think it's what's responsible for switching the hardware back over to use the init_mm page tables. If this check trips for init_mm, then the kernel will stay running on efi_mm when it's not intended to. Remember when I asked about whether there was going to be *a* kernel mm or lots? This is where it starts to matter. It's outside the diff context but the code here is basically: if (loaded_mm == &init_mm) return; switch_mm(NULL, &init_mm, NULL); So either all kernel mm's are equivalent or this code doesn't quite work. > /* Warn if we're not lazy. */ > @@ -855,7 +855,7 @@ void switch_mm_irqs_off(struct mm_struct *unused, struct mm_struct *next, > * cpu_tlbstate_shared.is_lazy whether or not to send an IPI. > */ > if (IS_ENABLED(CONFIG_DEBUG_VM) && > - WARN_ON_ONCE(prev != &init_mm && !is_notrack_mm(prev) && > + WARN_ON_ONCE(!mm_is_kernel(prev) && !is_notrack_mm(prev) && > !cpumask_test_cpu(cpu, mm_cpumask(next)))) > cpumask_set_cpu(cpu, mm_cpumask(next)); > > @@ -932,7 +932,8 @@ void switch_mm_irqs_off(struct mm_struct *unused, struct mm_struct *next, > * This way switch_mm() must see the new tlb_gen or > * flush_tlb_mm_range() must see the new loaded_mm, or both. > */ > - if (next != &init_mm && !cpumask_test_cpu(cpu, mm_cpumask(next))) > + if (!mm_is_kernel(next) && > + !cpumask_test_cpu(cpu, mm_cpumask(next))) > cpumask_set_cpu(cpu, mm_cpumask(next)); > else > smp_mb(); This one is interesting. It's basically saying that init_mm doesn't get mm_cpumask() updates. That makes sense since it has special TLB flushing rules. But what does this mean for efi_mm? Does it needs mm_cpumask() updates?