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]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1FA6EEE021A for ; Thu, 14 Sep 2023 02:49:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A6A9E6B025A; Wed, 13 Sep 2023 22:49:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A1B046B0270; Wed, 13 Sep 2023 22:49:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8E3996B0274; Wed, 13 Sep 2023 22:49:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 7E97B6B025A for ; Wed, 13 Sep 2023 22:49:44 -0400 (EDT) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 571CC1A0F53 for ; Thu, 14 Sep 2023 02:49:44 +0000 (UTC) X-FDA: 81233672688.03.7BA7C12 Received: from mailout2.samsung.com (mailout2.samsung.com [203.254.224.25]) by imf06.hostedemail.com (Postfix) with ESMTP id 270C2180012 for ; Thu, 14 Sep 2023 02:49:40 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=samsung.com header.s=mail20170921 header.b=VijfJeHH; dmarc=pass (policy=none) header.from=samsung.com; spf=pass (imf06.hostedemail.com: domain of jason.sim@samsung.com designates 203.254.224.25 as permitted sender) smtp.mailfrom=jason.sim@samsung.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1694659781; h=from:from:sender:sender:reply-to: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=r5jj0lu9AKPQ4dUW3z7RMHoNOH/8E0rIFCiEOm5ipWs=; b=yDEJ8mAJIZ3n/xungEnZzGfIxDCh15QDBgck5wOKH0Zt6HsUcESGa8ZyIzHNlv5XJFuqVR Z2UYtWEuk5JS+jMfL/m9DMADnmowWFvpqtil2tvm013LBgM9Dx2HVhQe2vyjQIEY+XxnDQ rLc21ZsMwxH/Zt0Uvk+8Z0wXl2eoayI= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=samsung.com header.s=mail20170921 header.b=VijfJeHH; dmarc=pass (policy=none) header.from=samsung.com; spf=pass (imf06.hostedemail.com: domain of jason.sim@samsung.com designates 203.254.224.25 as permitted sender) smtp.mailfrom=jason.sim@samsung.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1694659781; a=rsa-sha256; cv=none; b=x8K5FHW65802oqidzNqR6XywrxXYgt/NVTpi7A41+Sq5FhXyM8dOY07jR09dSt6Cm3tbaV uoELAY1Y/BSVg7YSBZpZhvX3s2J+oQ6C5L2qaATQKzNbEoZkTwEoUTOTHbblFIvd/C59+j mawGioFehtfy6zQpfwFVhR7ayfpV5tI= Received: from epcas1p3.samsung.com (unknown [182.195.41.47]) by mailout2.samsung.com (KnoxPortal) with ESMTP id 20230914024938epoutp02cad6b086ea8a1e4db23b10d7d8c35263~EpBbrNzeR0744107441epoutp02t for ; Thu, 14 Sep 2023 02:49:38 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout2.samsung.com 20230914024938epoutp02cad6b086ea8a1e4db23b10d7d8c35263~EpBbrNzeR0744107441epoutp02t DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1694659778; bh=r5jj0lu9AKPQ4dUW3z7RMHoNOH/8E0rIFCiEOm5ipWs=; h=Subject:Reply-To:From:To:CC:In-Reply-To:Date:References:From; b=VijfJeHHK9y4SaPTM/KGiziiRA855ziCcAFEjKiDGWOk+U7wDxdhfnBCDcbJxlNsj Vu4vv1lauoL+iSOSIiYLI2ho9pptyL+Goh70saqlQVm0KoU+0DK8OumTNvHFynKeD3 KGFUYFPXTU5hzv8racasjEJq71FR/wGziNeXFkd0= Received: from epsnrtp1.localdomain (unknown [182.195.42.162]) by epcas1p4.samsung.com (KnoxPortal) with ESMTP id 20230914024937epcas1p4f2a21bad5bfca9e0b18e255b3e05ae86~EpBbWYV1J2101721017epcas1p41; Thu, 14 Sep 2023 02:49:37 +0000 (GMT) Received: from epsmges1p3.samsung.com (unknown [182.195.38.247]) by epsnrtp1.localdomain (Postfix) with ESMTP id 4RmMH533hnz4x9Pr; Thu, 14 Sep 2023 02:49:37 +0000 (GMT) X-AuditID: b6c32a37-d85fa700000025ae-11-650274c19af9 Received: from epcas1p3.samsung.com ( [182.195.41.47]) by epsmges1p3.samsung.com (Symantec Messaging Gateway) with SMTP id 25.C3.09646.1C472056; Thu, 14 Sep 2023 11:49:37 +0900 (KST) Mime-Version: 1.0 Subject: Re: [PATCH] maple_tree: use GFP_KERNEL on mas_node_count Reply-To: jason.sim@samsung.com From: Jaeseon Sim To: "Liam R. Howlett" CC: Matthew Wilcox , Peng Zhang , "surenb@google.com" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "jaewon31.kim@gmail.com" , "maple-tree@lists.infradead.org" , Jaewon Kim X-Priority: 3 X-Content-Kind-Code: NORMAL In-Reply-To: <20230907144924.272e2f2sckprbvca@revolver> X-Drm-Type: N,general X-Msg-Generator: Mail X-Msg-Type: PERSONAL X-Reply-Demand: N Message-ID: <20230914024937epcms1p24be0b59caeefd7966bec81ac11feff8f@epcms1p2> Date: Thu, 14 Sep 2023 11:49:37 +0900 X-CMS-MailID: 20230914024937epcms1p24be0b59caeefd7966bec81ac11feff8f Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: SVC_REQ_APPROVE CMS-TYPE: 101P X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrIJsWRmVeSWpSXmKPExsWy7bCmvu7BEqZUg67lYhbdm2cyWvS+f8Vk sb3hAbvF5V1z2CzurfnParFhZQOTxeRLC9gsfv8Aij3985fZgdPj34k1bB47Z91l91iwqdRj 8wotj02fJrF7bF5S7/Hx6S0Wj74tqxg9Pm+SC+CMyrbJSE1MSS1SSM1Lzk/JzEu3VfIOjneO 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 j1QGTFhH 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=7C=20__GFP_NOWARN=0D=0A>=20>=20>=20>=20>=20>=20in=20order=20to=20allow=20m= emory=20reclaim.=0D=0A>=20>=20>=20>=20There=20are=20many=20paths=20that=20c= all=20maple=20tree's=20mas_node_count().=20Some=20paths=0D=0A>=20>=20>=20>= =20cannot=20reclaim=20memory.=0D=0A>=20>=20>=20=0D=0A>=20>=20>=20Right=20..= .=20but=20we=20should=20be=20handling=20the=20ENOMEM=20inside=20the=20maple= =20tree=20and=0D=0A>=20>=20>=20allocating=20some=20nodes=20with=20GFP_KERNE= L=20instead=20of=20failing=20fork().=0D=0A>=20>=20>=20=0D=0A>=20>=20>=20>= =20>=20What=20testing=20did=20you=20do=20of=20this=20patch?=20=20In=20parti= cular,=20did=20you=20try=20it=0D=0A>=20>=20>=20>=20>=20with=20lockdep=20ena= bled?=0D=0A>=20>=20I=20did=20power=20on/off=20test=20with=20this=20patch.= =0D=0A>=20>=20I=20did=20not=20try=20it=20with=20lockdep=20enabled.=0D=0A>= =20=0D=0A>=20To=20accomplish=20the=20same=20result,=20but=20with=20a=20much= =20smaller=20scope=20that=20will=0D=0A>=20work=20with=20lockdep,=20I=20woul= d=20suggest=20changing=20mas_expected_entries()=20to=0D=0A>=20use=20mas_nod= e_count_gfp()=20(which=20already=20exists)=20and=20pass=20in=20GFP_KERNEL.= =0D=0A>=20=0D=0A>=20Since=20fork=20is=20the=20only=20current=20user=20of=20= mas_expected_entries(),=20this=0D=0A>=20won't=20break=20other=20users=20and= =20we=20can=20deal=20with=20changing=20it=20for=20others=20if=0D=0A>=20it= =20is=20needed.=0D=0A>=20=0D=0A>=20If=20we=20do=20go=20this=20route,=20plea= se=20add=20a=20note=20in=20the=20documentation=20about=0D=0A>=20using=20GFP= _KERNEL.=0D=0A>=20=0D=0A>=20Willy,=20does=20that=20work=20for=20you?=0D=0A>= =20=0D=0A>=20Thanks,=0D=0A>=20Liam=0D=0A=0D=0ADear=20Liam,=0D=0ACan=20I=20a= sk=20you=20the=20reason=20why=20mas_node_count=20is=20using=20GFP_NOWAIT=20= =7C=20__GFP_NOWARN?=0D=0AI=20wonder=20if=20other=20callers=20for=20mas_node= _count=20might=20have=20similar=20issue.=0D=0A=0D=0AFrom=20your=20opinion,= =20I'll=20post=20v2=20patch=20as=20follows=0D=0A=0D=0Adiff=20--git=20a/lib/= maple_tree.c=20b/lib/maple_tree.c=0D=0Aindex=20ee1ff0c59fd7..b0229271c24e= =20100644=0D=0A---=20a/lib/maple_tree.c=0D=0A+++=20b/lib/maple_tree.c=0D=0A= =40=40=20-5574,7=20+5574,7=20=40=40=20int=20mas_expected_entries(struct=20m= a_state=20*mas,=20unsigned=20long=20nr_entries)=0D=0A=20=09/*=20Internal=20= nodes=20*/=0D=0A=20=09nr_nodes=20+=3D=20DIV_ROUND_UP(nr_nodes,=20nonleaf_ca= p);=0D=0A=20=09/*=20Add=20working=20room=20for=20split=20(2=20nodes)=20+=20= new=20parents=20*/=0D=0A-=09mas_node_count(mas,=20nr_nodes=20+=203);=0D=0A+= =09mas_node_count_gfp(mas,=20nr_nodes=20+=203,=20GFP_KERNEL);=0D=0A=20=0D= =0A=20=09/*=20Detect=20if=20allocations=20run=20out=20*/=0D=0A=20=09mas->ma= s_flags=20=7C=3D=20MA_STATE_PREALLOC;=0D=0A--=20=0D=0A2.17.1=0D=0A=0D=0ATha= nks=0D=0AJaeseon