From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794484460; b=xXNQ2LtrdksR/ic2OKIXMLAdXxZmlvwgLn20W4tYKLPLRL3MrRVVbnLy09YmBe+9/n9K SXxgVsb/Gz0/NGPtl4t6zACQtiftKK/cG+zCFSfbgdzexiLi7jv89nB3Bd9xWE1tp4DYK q5Qi8T9RptRpeHj1ooyAcAhY2rt+Pz54xT1rTP2ivB4fHp+R98/ke15w/y1qKuiUN5HK8 mVVYqdG1wN7ggJqypCKC/oBhja88b6lKTZgJ20dFXrvTGkdydp8PAkkptGDW10t6sCGdK tS217mGQ+sGmg1ViIpvqdcLsLMoWPq54rBHcIz5tO78Ap89RSfa2Y6vBvbWendcyv5A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794484460; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To; bh=JdYD/YdMuJulWiGGAlT2Rpi62/Bld2oVWED5RC6QjGA=; b=a1KL9evQNBLZh/uzUjSewxXX1bmoPo1Tmvxe+Ob4bwrLnBOSO1elyWaa3Klk2gTIqiKc l/ATAwO7rE+slvMVnba/ew+eg1T3rXdAawbtaPujeGYak5w+iTo7PZKCVb7xrL2QMmWrf Cyru7EDuLnKe6Ja0So0mb4GarmhSR1MhuueHyC8HlEdvi9q9h1YoNo646954FiTnMB0R/ 0h0zrUuBMgo6meJSouS0xbg9+JdwPK5LRydAHhpdlb7h5ULwfg2TNTwyxpMxUga9DjNc0 Aju42HJyGeMvL4tbS6a46S+nKj/C1YeTRwPMi7KwRttKEQamSExGLOvJdirLAkwxTmQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="iKZ/K1iq"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C5559606A321; Thu, 12 Nov 2026 11:54:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=iKZ/K1iq Received: by smtp.kernel.org (Postfix) with ESMTPSA id A9ED21F00A06; Thu, 12 Nov 2026 11:54:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794484460; bh=JdYD/YdMuJulWiGGAlT2Rpi62/Bld2oVWED5RC6QjGA=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=iKZ/K1iqB0cnLxYHoQ9uVxCv0b+d4WthJcUEBANL3iO8xDOAY1zdbGmaFlcNBFdFj m6kn2rPrgmUhvS4mRguW4tD9m7jcen5dda5WSkkV0cHEmXhfHUv6eYU3k1xSaNa79Z IXJyky1bTv0gT41CyD7OAkAEUA3rOtRlpcdlcDL/b5LdjB5gyB+HGCMaBWwoyV6fCI +9qQ5vZO5otJptN/vHoJckJUwGwf50A6JCcE9bUOcBSptoHJqtBiMqPxOEHbIUi/X8 vDJsTTqEMZPUFfr7/nUpNevSmO3bP7v9Onm5l/L9O5C8eglRGnAo3D8xeluHKe2ev5 30/GJP2YZRZKg== Date: Thu, 12 Nov 2026 11:54:11 +0000 From: "Lorenzo Stoakes (ARM)" To: "David Hildenbrand (Arm)" Cc: Usama Arif , Andrew Morton , apopple@nvidia.com, byungchul@sk.com, gourry@gourry.net, jannh@google.com, joshua.hahnjy@gmail.com, liam@infradead.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, matthew.brost@intel.com, mhocko@suse.com, pfalcato@suse.de, rppt@kernel.org, surenb@google.com, vbabka@kernel.org, ying.huang@linux.alibaba.com, ziy@nvidia.com, kas@kernel.org, hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, kernel-team@meta.com, baolin.wang@linux.alibaba.com, Nico Pache , ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, stable@vger.kernel.org Subject: Re: [PATCH 1/3] mm: don't PTE-batch a swap-in over a hardware-poisoned subpage Message-ID: References: <20261111113904.650722-1-usama.arif@linux.dev> <20261111113904.650722-2-usama.arif@linux.dev> X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Nov 12, 2026 at 09:56:39AM +0100, David Hildenbrand (Arm) wrote: > On 11/11/26 14:18, Lorenzo Stoakes (ARM) wrote: > > Hm, isn't scanning every single page in the folio potentially quite costly > > here? I thought the point of batching was to improve performance overall? > > Yeah, we don't really want another helper to check for hwpoison. > > If we race with concurrent hwpoison, bad luck. The slapped on memory-failure > code is full of races. That needs a proper long-term solution, not more pain to > core-mm. Yeah exactly. See Usama's reply - it really does narrow into a weird edge case. Scan there if you want to scan at all. Otherwise tough luck yes. > > So let's please try reusing existing helpers that test the large-folio bit. Yes please! -- Cheers, Lorenzo