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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().


  reply	other threads:[~2022-08-19 15:46 UTC|newest]

Thread overview: 13+ 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  0:25 ` folio_map Dave Chinner
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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