linux-kernel - Re: [RFC PATCH v2 1/2] ARM/mm/fault: always goto bad_area when handling with page faults of kernel address

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Message-ID: <aSnVXrnuY9QKjTKg@shell.armlinux.org.uk>
Date: Fri, 28 Nov 2025 17:01:18 +0000
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: Xie Yuanbin <xieyuanbin1@...wei.com>, akpm@...ux-foundation.org,
	arnd@...db.de, brauner@...nel.org, david.laight@...box.com,
	hch@....de, jack@...e.com, kuninori.morimoto.gx@...esas.com,
	liaohua4@...wei.com, lilinjie8@...wei.com,
	linux-arm-kernel@...ts.infradead.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	lorenzo.stoakes@...cle.com, marc.zyngier@....com, nico@...xnic.net,
	pangliyuan1@...wei.com, pfalcato@...e.de, punitagrawal@...il.com,
	rjw@...ysocki.net, rppt@...nel.org, tony@...mide.com,
	vbabka@...e.cz, viro@...iv.linux.org.uk, wangkefeng.wang@...wei.com,
	will@...nel.org, wozizhi@...weicloud.com
Subject: Re: [RFC PATCH v2 1/2] ARM/mm/fault: always goto bad_area when
 handling with page faults of kernel address

On Fri, Nov 28, 2025 at 01:03:59PM +0100, Sebastian Andrzej Siewior wrote:
> On 2025-11-28 10:27:56 [+0800], Xie Yuanbin wrote:
> > According to the discussion, it might be better to handle the kernel
> > address fault directly, just like what x86 does, instead of finding VMA.
> 
> the kernel fault shouldn't have a VMA
> 
> > Link: https://elixir.bootlin.com/linux/v6.18-rc7/source/arch/x86/mm/fault.c#L1473
> > ```c
> > 	if (unlikely(fault_in_kernel_space(address)))
> > 		do_kern_addr_fault(regs, error_code, address);
> > 	else
> > 		do_user_addr_fault(regs, error_code, address);
> > ```
> > 
> > It seems your patches hasn't been merged into the linux-next branch yet.
> 
> I hope Russell will add them once he gets to it. They got reviewed, I
> added them to the patch system.

I'm not sure which patches you're talking about, but discussion is
still ongoing, so it would be greatly premature to merge anything.

https://lore.kernel.org/r/aSmUnZZATTn3JD7m@willie-the-truck

There are now many threads each with their own discussion, which
makes it more difficult to work out which is the implementation that
should be merged. Clearly, not everyone knows about the other
discussion threads.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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