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X-CSE-ConnectionGUID: zeFAXlBbRKCtqmz3pOVysA== X-CSE-MsgGUID: n8dgpmqcTlestGuSI60OgQ== X-IronPort-AV: E=McAfee;i="6800,10657,11544"; a="70886470" X-IronPort-AV: E=Sophos;i="6.18,242,1751266800"; d="scan'208";a="70886470" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by orvoesa104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Sep 2025 12:22:44 -0700 X-CSE-ConnectionGUID: 16H5ou9jSV+0JKaCGN7ZtA== X-CSE-MsgGUID: c5k4hfHMTkSEHY8E23Jbww== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.18,242,1751266800"; d="scan'208";a="195899615" Received: from vverma7-desk1.amr.corp.intel.com (HELO [10.125.110.42]) ([10.125.110.42]) by fmviesa002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Sep 2025 12:22:43 -0700 Message-ID: <10d2f466-4660-4439-a5fb-dfc4384ca432@intel.com> Date: Fri, 5 Sep 2025 12:22:42 -0700 Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 5/8] x86/mm: Use pagetable_free() To: Jason Gunthorpe , Lu Baolu Cc: Joerg Roedel , Will Deacon , Robin Murphy , Kevin Tian , Jann Horn , Vasant Hegde , Alistair Popple , Peter Zijlstra , Uladzislau Rezki , Jean-Philippe Brucker , Andy Lutomirski , Yi Lai , iommu@lists.linux.dev, security@kernel.org, linux-kernel@vger.kernel.org References: <20250905055103.3821518-1-baolu.lu@linux.intel.com> <20250905055103.3821518-6-baolu.lu@linux.intel.com> <20250905184115.GQ616306@nvidia.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/5/25 11:41, Jason Gunthorpe wrote: ... >> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c >> index 76e33bd7c556..86b4297c1984 100644 >> --- a/arch/x86/mm/init_64.c >> +++ b/arch/x86/mm/init_64.c >> @@ -1013,7 +1013,7 @@ static void __meminit free_pagetable(struct page *page, int order) >> free_reserved_pages(page, nr_pages); >> #endif >> } else { >> - free_pages((unsigned long)page_address(page), order); >> + pagetable_free(page_ptdesc(page)); >> } >> } > > Er.. So if bootmem happens to be under the table and we happen to free > it due to memory hotplug we don't go through the SVA fixing path? > > Seems wrong?? Yes, it does. > Bootmem still has a ptdesc and a usable linked list, right? Yep, I think so. > So maybe this should be redone into an arch hook in/around > __pagetable_free() and all the above frees just use the normal ptdesc > free path, including the SVA work queue? There are reserved pages and the put_page_bootmem() ones too. The put_page_bootmem() ones are especially annoying because they can't always be freed. put_page_bootmem() only has three call sites. Maybe we should just make it return if the caller *should* free the page instead of actually freeing it. Then we get something like: free_pagetable() { if (PageReserved(page)) { if (is_bootmem(page) && put_page_bootmem(page)) { // refcount didn't drop to 0, can't free return; } unreserve_page(page); } pagetable_free(page_ptdesc(page)); } Which doesn't seem too bad.