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08 Jul 2022 10:01:46 -0700 X-IronPort-AV: E=Sophos;i="5.92,256,1650956400"; d="scan'208";a="626764382" Received: from yyan2-mobl2.amr.corp.intel.com (HELO [10.212.242.16]) ([10.212.242.16]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jul 2022 10:01:45 -0700 Message-ID: Date: Fri, 8 Jul 2022 10:01:37 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH] x86/mm/tlb: ignore f->new_tlb_gen when zero Content-Language: en-US To: Nadav Amit Cc: David Hildenbrand , LKML , Hugh Dickins , Thomas Gleixner , Ingo Molnar , Borislav Petkov , X86 ML , Linux MM , Dave Hansen , Peter Zijlstra , Andy Lutomirski References: <20220708003053.158480-1-namit@vmware.com> <283d7660-000a-81af-1d6b-4fdedcb6dfd8@intel.com> From: Dave Hansen In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=EuysoWED; 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dkim=pass header.d=intel.com header.s=Intel header.b=EuysoWED; spf=none (imf27.hostedemail.com: domain of dave.hansen@intel.com has no SPF policy when checking 192.55.52.136) smtp.mailfrom=dave.hansen@intel.com; dmarc=pass (policy=none) header.from=intel.com X-Rspamd-Server: rspam11 X-HE-Tag: 1657299710-43737 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: On 7/8/22 09:54, Nadav Amit wrote: > Since the bug was not during MADV_DONTNEED there is no reason for the > results to be any different. > > Famous last words? Considering that your patch broke the kernel a way that surprised us all, I think caution is warranted. Re-running a microbenchmark that takes five minutes and stresses things a bit is the least you can do, I think.