linux-kernel - Re: [RFC PATCH 0/2] mm: update mips to use do_mmap(), make mmap

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Message-ID: <Z2E06z9yw+/Jb4Yo@alpha.franken.de>
Date: Tue, 17 Dec 2024 09:23:07 +0100
From: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	"Liam R . Howlett" <Liam.Howlett@...cle.com>,
	Vlastimil Babka <vbabka@...e.cz>, Jann Horn <jannh@...gle.com>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	linux-mips@...r.kernel.org
Subject: Re: [RFC PATCH 0/2] mm: update mips to use do_mmap(), make
 mmap_region() internal

On Thu, Dec 12, 2024 at 03:36:45PM +0000, Lorenzo Stoakes wrote:
> Currently the only user of mmap_region() outside of the memory management
> code is the MIPS VDSO implementation.
> 
> This uses mmap_region() to map a 'delay slot emulation page' at the top of
> the stack which is read-only and executable.
> 
> This mapping requires that an already-acquired mmap write lock is utilised
> and that uffd and populate logic is ignored. This rules out vm_mmap(),
> however do_mmap() fits the bill.
> 
> Adapt this code to use do_mmap() and then once done, make mmap_region()
> internal and userland testable, and avoid any other uses of mmap_region(),
> which is absolutely and strictly an internal mm function which bypasses a
> great number of checks and logic.
> 
> REVIEWERS NOTES:
> 
> Thomas - I lack the hardware or set up to test this beyond a simple
> cross-compilation test, so I need some input from you MIPS guys as to
> whether this is workable.
> 
> I've therefore sent this as an RFC so we can be sure this is suitable!
> Please could you check to make sure this change is OK and I haven't missed
> anything?

conversation looks correct, but this patch doesn't apply to upstream v6.13-rc1.
Which tree are you using ?

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]