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X-CSE-ConnectionGUID: 3npbsiA7Q26ye0a0xSwUgg== X-CSE-MsgGUID: jKiOAtTKRdCdTQjhWBPnig== X-IronPort-AV: E=McAfee;i="6800,10657,11804"; a="85002828" X-IronPort-AV: E=Sophos;i="6.24,181,1774335600"; d="scan'208";a="85002828" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by orvoesa106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Jun 2026 13:25:15 -0700 X-CSE-ConnectionGUID: hQ2f19pNTPm8IvPDw4EXnQ== X-CSE-MsgGUID: ma2HkNjqSdCRWye5Mr8ahQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.24,181,1774335600"; d="scan'208";a="243519500" Received: from aduenasd-mobl5.amr.corp.intel.com (HELO [10.125.108.20]) ([10.125.108.20]) by orviesa008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Jun 2026 13:25:14 -0700 Message-ID: <53b599ef-0f16-44d9-bfda-a5a751649193@intel.com> Date: Mon, 1 Jun 2026 13:25:12 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] arch,x86: Skip setting align_offset for hugetlb mappings To: Oscar Salvador , Andrew Morton Cc: Dave Hansen , Borislav Petkov , Karsten Desler , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20260601125015.216110-1-osalvador@suse.de> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 44C3A4000D X-Stat-Signature: wqsqen38w3nboi81fg97xrhktztnowwr X-Rspam-User: X-HE-Tag: 1780345516-934797 X-HE-Meta: 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 PtAs1Q+H dTnjMV6+bHlRZMen/r3sFHmLISEnLI9kklTpgX7n0q0fQBO2vttPowSr7isEHG9qx5NQzP8BNx5sv3vtpLKLnE/mh10KO6Q90RQ1XN9GPIjzU8hR1R2C4qsYncS9xqn1I+GZq+pumeoPHXzc6gxVAgVt5ANa0aOGvc1Sb6+oG1sgkGoh010iflRO67SXiEdR9kYSAh02KL4Jrz+GQVAT4GZn7MjogUHDACTO7f8JrbvhZclOGaIb3OkfBeg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 6/1/26 05:50, Oscar Salvador wrote: > On x86, arch_get_unmapped_area{_topdown} set align_offset in order to avoid > cache aliasing on I$ on AMD family 15h when 'align_va_addr' is enabled. I'm sorry, but this is a big NAK from the x86 side, without at _least_ a substantially improved changelog and evidence that x86 is both the only place to reasonably fix this _and_ evidence that no other arch is affected. Why? x86 is not the only architecture that uses .align_offset. The bug was introduced in a generic, non-x86 commit (7bd3f1e1a9ae) The real fix is almost surely in arch-generic code. So my fear is that we'll apply the x86 thing. Four other architectures will come along and have to add their own fixes. Then (if we're lucky) someone will stick around and fix it properly, than all the architectures will have to remove their hacks. Worst-case, we end up with a latent bug, just without any testing coverage because x86 testing is the most broad. Oscar, even if the real fix involves a couple of patches, can we please see that, first? Then, we can go back and make an informed decision about hacks versus proper fixes. Second, if there's a hack to be had, it should probably be to back out the AMD optimization. That's absolutely an x86-only thing. Third, I have zero issues with distros adding and carrying the x86 align_offset hack. That's what kernel distros are *for*.