From: Sidhartha Kumar <sidhartha.kumar@oracle.com>
To: Deepak R Varma <drv@mailo.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
willy@infradead.org
Cc: Saurabh Singh Sengar <ssengar@microsoft.com>,
Praveen Kumar <kumarpraveen@linux.microsoft.com>
Subject: Re: Query on mm/folio-compat: pagecache_get_page
Date: Tue, 14 Feb 2023 10:35:33 -0800 [thread overview]
Message-ID: <ce84bac6-b868-76f9-4678-d3eeed42eae3@oracle.com> (raw)
In-Reply-To: <Y+vRpvwNgwDB4MS0@ubun2204.myguest.virtualbox.org>
On 2/14/23 10:23 AM, Deepak R Varma wrote:
> Hello,
> Could someone comment if it is safe to access the page member variable as
> written on line #100 when folio is NULL as returned from the
It is safe to access the page member variable when folio is NULL because
the offset of page within struct folio is 0.[1]
[1] https://lore.kernel.org/lkml/Y7h4jsv6jl0XSIsk@casper.infradead.org/T/
Thanks,
Sidhartha Kumar
> __filemap_get_folio() function call? Is this kind of intentional page-fault
> trigger for the system to handle a new/fresh page allocation?
>
> 2 folio = __filemap_get_folio(mapping, index, fgp_flags, gfp);
> 1 if (!folio || xa_is_value(folio))
> 100 return &folio->page;
> 1 return folio_file_page(folio, index);
>
> The code is part of commit ID c5255b421fd04
>
> Thank you,
> ./drv
>
>
>
next prev parent reply other threads:[~2023-02-14 18:35 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-14 18:23 Query on mm/folio-compat: pagecache_get_page Deepak R Varma
2023-02-14 18:35 ` Sidhartha Kumar [this message]
2023-02-14 19:17 ` Deepak R Varma
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