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Wed, 31 Mar 2021 04:09:57 +0000 Received: from [10.2.63.109] (172.20.145.6) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 31 Mar 2021 04:09:56 +0000 Subject: Re: [PATCH v7 3/8] mm/rmap: Split try_to_munlock from try_to_unmap From: John Hubbard To: Alistair Popple CC: Jason Gunthorpe , , , , , , , , , , , , , , Christoph Hellwig References: <20210326000805.2518-1-apopple@nvidia.com> <20210330222440.GC2356281@nvidia.com> <12636584.zsJ0Sx4KLp@nvdebian> Message-ID: <5f156670-e8d0-e62a-2286-764687a6669f@nvidia.com> Date: Tue, 30 Mar 2021 21:09:56 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US X-Originating-IP: [172.20.145.6] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) To HQMAIL107.nvidia.com (172.20.187.13) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: b1e0ab9e-2a38-4cd6-d901-08d8f3fad8c5 X-MS-TrafficTypeDiagnostic: CH2PR12MB4247: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:10000; 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X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 31 Mar 2021 04:09:57.5524 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: b1e0ab9e-2a38-4cd6-d901-08d8f3fad8c5 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.112.34];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BN8NAM11FT051.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH2PR12MB4247 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: D3AA590009EC X-Stat-Signature: yazna96kbsm7ffemrwyfjhjp7137481s Received-SPF: none (nvidia.com>: No applicable sender policy available) receiver=imf19; identity=mailfrom; envelope-from=""; helo=NAM10-BN7-obe.outbound.protection.outlook.com; client-ip=40.107.92.79 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1617163798-938674 Content-Transfer-Encoding: quoted-printable 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 3/30/21 8:56 PM, John Hubbard wrote: > On 3/30/21 3:56 PM, Alistair Popple wrote: > ... >>> +1 for renaming "munlock*" items to "mlock*", where applicable. good = grief. >> >> At least the situation was weird enough to prompt further investigatio= n :) >> >> Renaming to mlock* doesn't feel like the right solution to me either t= hough. I >> am not sure if you saw me responding to myself earlier but I am thinki= ng >> renaming try_to_munlock() -> page_mlocked() and try_to_munlock_one() -= > >> page_mlock_one() might be better. Thoughts? >> >=20 > Quite confused by this naming idea. Because: try_to_munlock() returns > void, so a boolean-style name such as "page_mlocked()" is already not a > good fit. >=20 > Even more important, though, is that try_to_munlock() is mlock-ing the > page, right? Is there some subtle point I'm missing? It really is doing > an mlock to the best of my knowledge here. Although the kerneldoc > comment for try_to_munlock() seems questionable too: >=20 > /** > * try_to_munlock - try to munlock a page > * @page: the page to be munlocked > * > * Called from munlock code.=C2=A0 Checks all of the VMAs mapping the pa= ge > * to make sure nobody else has this page mlocked. The page will be > * returned with PG_mlocked cleared if no other vmas have it mlocked. > */ >=20 > ...because I don't see where, in *this* routine, it clears PG_mlocked! >=20 > Obviously we agree that a routine should be named based on what it does= , > rather than on who calls it. So I think that still leads to: >=20 > =C2=A0=C2=A0=C2=A0 try_to_munlock() --> try_to_mlock() > =C2=A0=C2=A0=C2=A0 try_to_munlock_one() --> try_to_mlock_one() >=20 > Sorry if I'm missing something really obvious. Actually, re-reading your and Jason's earlier points in the thread, I see that I'm *not* missing anything, and we are actually in agreement about h= ow the code operates. OK, good! Also, as you point out above, maybe the "try_" prefix is not really accur= ate either, given how this works. So maybe we have arrived at something like: try_to_munlock() --> page_mlock() // or mlock_page()... try_to_munlock_one() --> page_mlock_one() thanks, --=20 John Hubbard NVIDIA