linux-kernel - Re: [PATCH v2] Documentation/mm: Add information about kmap_local

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Message-ID: <970a881a-cdaf-2568-657a-3b93b0273338@infradead.org>
Date:   Sat, 1 Jul 2023 16:59:04 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
        Jonathan Corbet <corbet@....net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Mike Rapoport (IBM)" <rppt@...nel.org>,
        Deming Wang <wangdeming@...pur.com>,
        Ira Weiny <ira.weiny@...el.com>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Catalin Marinas <catalin.marinas@....com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Peter Collingbourne <pcc@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vlastimil Babka <vbabka@...e.cz>, Will Deacon <will@...nel.org>
Subject: Re: [PATCH v2] Documentation/mm: Add information about
 kmap_local_folio()



On 7/1/23 16:54, Matthew Wilcox wrote:
> On Sat, Jul 01, 2023 at 08:21:20AM -0700, Randy Dunlap wrote:
>>> -* kmap_local_page().  This function is used to require short term mappings.
>>> -  It can be invoked from any context (including interrupts) but the mappings
>>> -  can only be used in the context which acquired them.
>>> -
>>> -  This function should always be used, whereas kmap_atomic() and kmap() have
>>> +* kmap_local_page(), kmap_local_folio() - These functions are used to require
>>
>>                                                                          acquire ?
> 
> "create" might be better?

Yes, that's good.

>>> +  short term mappings. They can be invoked from any context (including
>>> +  interrupts) but the mappings can only be used in the context which acquired
>>> +  them. The only differences between them consist in the first taking a pointer
>>> +  to a struct page and the second taking a pointer to struct folio and the byte
>>> +  offset within the folio which identifies the page.
>>
>> -- 
>> ~Randy

-- 
~Randy