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X-CSE-ConnectionGUID: FtyN1Q9WSuaOSDqBCkwyuQ== X-CSE-MsgGUID: Hg4v5aCxRluMhWCtFtpUdg== X-IronPort-AV: E=McAfee;i="6700,10204,11345"; a="57730777" X-IronPort-AV: E=Sophos;i="6.13,286,1732608000"; d="scan'208";a="57730777" Received: from fmviesa007.fm.intel.com ([10.60.135.147]) by orvoesa102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Feb 2025 11:57:47 -0800 X-CSE-ConnectionGUID: nXEU6dxwQte7N5t79NmDQg== X-CSE-MsgGUID: 5pa3RgP/SAGfmjHcRMASNA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.13,286,1732608000"; d="scan'208";a="113520739" Received: from tjmaciei-mobl5.ger.corp.intel.com (HELO [10.125.109.21]) ([10.125.109.21]) by fmviesa007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Feb 2025 11:57:46 -0800 Message-ID: <25b9d3f5-bfe8-48a9-b11b-819d19cfae1e@intel.com> Date: Fri, 14 Feb 2025 11:57:50 -0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC 1/1] x86/vmemmap: Add missing update of PML4 table / PML5 table entry To: Gwan-gyeong Mun , linux-kernel@vger.kernel.org Cc: osalvador@suse.de, 42.hyeyoo@gmail.com, byungchul@sk.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, akpm@linux-foundation.org, max.byungchul.park@sk.com, max.byungchul.park@gmail.com References: <20250214195151.168306-1-gwan-gyeong.mun@intel.com> <20250214195151.168306-2-gwan-gyeong.mun@intel.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 2/14/25 11:51, Gwan-gyeong Mun wrote: > when performing vmemmap populate, if the entry of the PML4 table/PML5 table > pointing to the target virtual address has never been updated, a page fault > occurs when the memset(start) called from the vmemmap_use_new_sub_pmd() > execution flow. "Page fault" meaning oops? Or something that we manage to handle and return from without oopsing? > This fixes the problem of using the virtual address without updating the > entry in the PML4 table or PML5 table. But this is a temporary solution to > prevent page fault problems, and it requires improvement of the routine > that updates the missing entry in the PML4 table or PML5 table. Can we please skip past the band-aid and go to the real fix?