From: Matthew Wilcox <willy@infradead.org>
To: Uladzislau Rezki <urezki@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ira Weiny <ira.weiny@intel.com>,
"Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
Luis Chamberlain <mcgrof@kernel.org>,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC] vmap_folio()
Date: Fri, 19 Aug 2022 16:45:05 +0100 [thread overview]
Message-ID: <Yv+wAS9JXbYvufaW@casper.infradead.org> (raw)
In-Reply-To: <Yv9rrDY2qukhvzs5@pc636>
On Fri, Aug 19, 2022 at 12:53:32PM +0200, Uladzislau Rezki wrote:
> Looks pretty straightforward. One thing though, if we can combine it
> together with vmap(), since it is a copy paste in some sense, say to
> have something __vmap() to reuse it in the vmap_folio() and vmap().
>
> But that is just a thought.
Thanks for looking it over!
Combining it with vmap() or vm_map_ram() is tricky. Today, we assume
that each struct page pointer refers to exactly PAGE_SIZE bytes, so if
somebody calls alloc_pages(GFP_COMPOUND, 4) and then passes the head
page to vmap(), only that one page gets mapped. I don't know whether
any current callers depend on that behaviour.
Now that I look at the future customers of this, I think I erred in basing
this on vmap(), it looks like vm_map_ram() is preferred. So I'll redo
based on vm_map_ram().
next prev parent reply other threads:[~2022-08-19 15:45 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-16 18:08 folio_map Matthew Wilcox
2022-08-16 21:23 ` folio_map John Hubbard
2022-08-17 10:29 ` folio_map Kirill A. Shutemov
2022-08-17 19:38 ` folio_map Matthew Wilcox
2022-08-17 20:23 ` folio_map Ira Weiny
2022-08-17 20:52 ` folio_map Ira Weiny
2022-08-17 21:34 ` folio_map Matthew Wilcox
2022-08-18 1:28 ` folio_map Ira Weiny
2022-08-18 21:10 ` [RFC] vmap_folio() Matthew Wilcox
2022-08-19 10:53 ` Uladzislau Rezki
2022-08-19 15:45 ` Matthew Wilcox [this message]
2022-08-22 19:54 ` Uladzislau Rezki
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