From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 53303C61DBD for ; Wed, 26 Aug 2026 13:57:54 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5D6606B0095; Wed, 26 Aug 2026 09:57:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5876E6B0096; Wed, 26 Aug 2026 09:57:53 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 44EF46B0098; Wed, 26 Aug 2026 09:57:53 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 1A8A96B0095 for ; Wed, 26 Aug 2026 09:57:53 -0400 (EDT) Received: from smtpin28.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 880EF140110 for ; Wed, 26 Aug 2026 13:57:52 +0000 (UTC) X-FDA: 85143573984.28.187CD16 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) by imf06.hostedemail.com (Postfix) with ESMTP id 08203180007 for ; Wed, 26 Aug 2026 13:57:49 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=ibm.com header.s=pp1 header.b=YsU0NAN8; spf=pass (imf06.hostedemail.com: domain of imbrenda@linux.ibm.com designates 148.163.158.5 as permitted sender) smtp.mailfrom=imbrenda@linux.ibm.com; dmarc=pass (policy=none) header.from=ibm.com ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1787752670; b=iOwKR75cJHxN0KH6mGZKuqd8FL1GqObU05kSVCkl3zufsFN6007xaamygt4H5wHB6Ffzjz 7dCqthO9UqBuQkEMxF92qYLPefUAs9ijYf9hcQPPpgZWVFnHuB0xZRE952Kzjo+9FGAtDj O+3UMDJb2cA8atKO67YT8PzSIupjL0E= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1787752670; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=2LiKUNUJ1OiL3bYqU+s9DlRnAseVi3cKYOI6b9crRyc=; b=HDfivqtJUSTz0MBRSmcxY17dnWJCRe1lW3y5KjaTb1/UfadzOJpCYz6FhfnqZhw9olG67B SzHIy2di/r1Va4owByEf0+zQUCZgwyqRpOyvIOiVyjzUlfKDKEfBSuwBoRQWUQY4Lrt7ph u/T0rxt0JsENL9X+SYtG4J//f5qsn20= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=ibm.com header.s=pp1 header.b=YsU0NAN8; spf=pass (imf06.hostedemail.com: domain of imbrenda@linux.ibm.com designates 148.163.158.5 as permitted sender) smtp.mailfrom=imbrenda@linux.ibm.com; dmarc=pass (policy=none) header.from=ibm.com Received: from pps.filterd (m0356516.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 67QCWEOD3894025; Wed, 26 Aug 2026 13:57:29 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=2LiKUN UJ1OiL3bYqU+s9DlRnAseVi3cKYOI6b9crRyc=; b=YsU0NAN8ubXRkP699Yyag+ ++z/zJObPD2qbkgKdy/Y+NMGzk+v3l3MAQ53dM6POe5oMAxpiSCu/gErd+Ono45z YCNS03vUkwrd7NOf3Oyym8vkP02mExnkwnVi6GvKIMQpZtyb+X/qs1FxX692cgoZ dJvyRH7nE0AIP5mCbsdRrkD73Q37dcR6BO1DW1TeFZdqyhuzpaiqNf29TZlcgNDf 5gWpxcP0owI5YAQFvUfHBsNGZLN0UCQCWWa8nDB0zp9CxssVYgGdxrhYT5aCMfZA A4DskgeC7F4VNjUM3aQzIQ4d0kGJPhXy4obYgW0mwgsNL3piwyoBXi6pizrCiFTQ == Received: from ppma23.wdc07v.mail.ibm.com (5d.69.3da9.ip4.static.sl-reverse.com [169.61.105.93]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4g716hy57w-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 26 Aug 2026 13:57:28 +0000 (GMT) Received: from pps.filterd (ppma23.wdc07v.mail.ibm.com [127.0.0.1]) by ppma23.wdc07v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 67QDfImv014111; Wed, 26 Aug 2026 13:57:27 GMT Received: from smtprelay06.fra02v.mail.ibm.com ([9.218.2.230]) by ppma23.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4g7qkha6v9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 26 Aug 2026 13:57:27 +0000 (GMT) Received: from smtpav03.fra02v.mail.ibm.com (smtpav03.fra02v.mail.ibm.com [10.20.54.102]) by smtprelay06.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 67QDvPxn36307332 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 26 Aug 2026 13:57:25 GMT Received: from smtpav03.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7176120043; Wed, 26 Aug 2026 13:57:25 +0000 (GMT) Received: from smtpav03.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E4CB620040; Wed, 26 Aug 2026 13:57:24 +0000 (GMT) Received: from p-imbrenda (unknown [9.224.75.30]) by smtpav03.fra02v.mail.ibm.com (Postfix) with SMTP; Wed, 26 Aug 2026 13:57:24 +0000 (GMT) Date: Wed, 26 Aug 2026 15:57:22 +0200 From: Claudio Imbrenda To: Hugh Dickins Cc: Andrew Morton , Ackerley Tng , Alexander Viro , Baolin Wang , Barry Song , Binbin Wu , Christian Brauner , Christoph Hellwig , Christoph Lameter , David Hildenbrand , JP Kobryn , Jan Kara , Jens Axboe , Johannes Weiner , Kairui Song , Kiryl Shutsemau , Lance Yang , Leonardo Bras , Lorenzo Stoakes , Marcelo Tosatti , Matthew Wilcox , Mel Gorman , Miaohe Lin , Michal Hocko , Minchan Kim , Muchun Song , Oscar Salvador , Peter Zijlstra , Qi Zheng , Rik van Riel , Sebastian Andrzej Siewior , Shakeel Butt , Suren Baghdasaryan , Vlastimil Babka , Yang Shi , Yu Zhao , "Zach O'Keefe" , Zi Yan , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 20/25] s390/fbatch: no lru_add_drain_all() in s390_wiggle_split_folio() Message-ID: <20260826155722.0198d3ce@p-imbrenda> In-Reply-To: <7bf68e7b-f88c-6ca9-39ab-e9fedab0c8be@google.com> References: <14a16945-529b-8bc0-ab38-3ea97e54e223@google.com> <7bf68e7b-f88c-6ca9-39ab-e9fedab0c8be@google.com> Organization: IBM X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Info: AW1haW4tMjYwODI2MDExMiBTYWx0ZWRfX6oBMoAXUz9b+ R2tF2RTZdZcuqOBhxLba2axaGWhWg2Kl07rlyQKuFHwjSqkOxhSrWknwqzByANHgzXMIgsDlaEU Idl+30dokbx5c7aGM1azQMrbbL2NzlU= X-Proofpoint-GUID: ic4DR_A9PttbjD9aBnZ6wMO72ql0cvfP X-Proofpoint-ORIG-GUID: CtVKpmKXa-6fjrMbMK0sces9C8ZO455o X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODI2MDExMiBTYWx0ZWRfX7/j9vZ3raXyB Me/IVg+MC4rfQk452IoupMj8YDfCrRb2aDsOD5v2ra95DbPAkxcv7e6jEP0qwG0PZO4yv1Dhl8A MDor97CDbv2jWwZubFtFo71f50APNaOXyPErDM8wuF9ANlsKg4R8mN1ETfKeEs7LY/eu1rcSswR ujmCkelqB5shvDHGHK7KQOqUTjGxr+/PE2dnk7Tzh0Q9LtWA/LNTZI2nOT5w+ACGn+182t/6tXK bPa8WHzBebLfwFyGylResRBGUAtgIcfqoeAZhfcwRefUAXVTJ8Ojiq7mZr55C0JybbHa7HV8jvi 8uJw1ELRQYwi4ziuvlfXVFScGfFjx3IZg7prbBCfBy1ZK0LLB7Ui/X3wJ8bY09SA4c4pI3mYqwv qNrzli/jLZlc8rSiWLGU7lnDa8/sZ5pE5EOrVG5HVnBjdZ3HWdNB9DZb6M4ma79dfwpc/F0B57l J4jca6EyH0POQCLZBWQ== X-Authority-Analysis: v=2.4 cv=H7brBeYi c=1 sm=1 tr=0 ts=6a8ef0c9 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=kj9zAlcOel0A:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=1XWaLZrsAAAA:8 a=67rAruxoP-Qw-q3ESxAA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-26_03,2026-08-26_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 malwarescore=0 lowpriorityscore=0 impostorscore=0 spamscore=0 bulkscore=0 adultscore=0 priorityscore=1501 clxscore=1011 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608260112 X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 08203180007 X-Stat-Signature: 9nnekcbb4y3wtnusrfnwg333rwpwm5fg X-HE-Tag: 1787752669-769214 X-HE-Meta: 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 uf4uyXFx wKg6d26rOFqKS/GNd9tAs3cXKnoAmcspzHG3UHdk5F1+nFPRjcEG86Zt9jawykp1f24rxEsRBiMIB/JtD7eGi2JK9O5+cSd4f+l5eOGTkXn1nqtn7YtuHXHMpyJRi2AuR88bQVS/Y8ilKRmKd1qTT0ju2gIyqitJaIKcCYcM3P2mcJSZq/mCA2585hQmtHWWWOI5g2GYlp9j1aYkRIEWbSzCbbcTge90UX7KqRM72sFhEj1U+EDUuqJtbNwiCjlxNxt5MP6ZzTz/2YAIaUdA7kUjghXb+DI83giLWwtq7VmUnsHLNeroI7nUMFhrem053bYKWxmRxKtLrljnVFmJNJ3eR+crIuK8LOvU6f45NtyqxAYqO+qNCkBy9lA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 24 Aug 2026 07:39:12 -0700 (PDT) Hugh Dickins wrote: > s390_wiggle_split_folio() has no good reason to lru_add_drain_all(), > now that the per-cpu fbatch references are gone. > > Signed-off-by: Hugh Dickins > --- > arch/s390/kernel/uv.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c > index dc14ebc0105b..120a467026a5 100644 > --- a/arch/s390/kernel/uv.c > +++ b/arch/s390/kernel/uv.c > @@ -364,7 +364,6 @@ int s390_wiggle_split_folio(struct mm_struct *mm, struct folio *folio) > > lockdep_assert_not_held(&mm->mmap_lock); > folio_wait_writeback(folio); > - lru_add_drain_all(); > > if (!folio_test_large(folio)) > return 0; This is black magic for me, I am not sure I fully understand all the details, but what's the new purpose of lru_add_drain_all() ? will we have a guarantee that no stray references to mapped folios will ever remain? Any unexpected reference (i.e. not due to mappings, see expected_folio_refs()) will cause a protected guest to hang.