linux-kernel - Re: [PATCH RESEND 1/1] um: oops on accessing a non-present page in the vmalloc area

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Date: Tue, 19 Mar 2024 23:18:05 +0100 (CET)
From: Richard Weinberger <richard@....at>
To: Petr Tesarik <petrtesarik@...weicloud.com>
Cc: anton ivanov <anton.ivanov@...bridgegreys.com>, 
	Johannes Berg <johannes@...solutions.net>, 
	linux-um <linux-um@...ts.infradead.org>, 
	linux-kernel <linux-kernel@...r.kernel.org>, 
	Roberto Sassu <roberto.sassu@...weicloud.com>, 
	petr <petr@...arici.cz>
Subject: Re: [PATCH RESEND 1/1] um: oops on accessing a non-present page in
 the vmalloc area

----- Ursprüngliche Mail -----
> Von: "Petr Tesarik" <petrtesarik@...weicloud.com>
> An: "richard" <richard@....at>, "anton ivanov" <anton.ivanov@...bridgegreys.com>, "Johannes Berg"
> <johannes@...solutions.net>, "linux-um" <linux-um@...ts.infradead.org>, "linux-kernel" <linux-kernel@...r.kernel.org>
> CC: "Roberto Sassu" <roberto.sassu@...weicloud.com>, "petr" <petr@...arici.cz>
> Gesendet: Montag, 18. März 2024 14:09:07
> Betreff: Re: [PATCH RESEND 1/1] um: oops on accessing a non-present page in the vmalloc area

> On 3/12/2024 4:07 PM, Petr Tesarik wrote:
>> On 2/23/2024 3:04 PM, Petr Tesarik wrote:
>>> From: Petr Tesarik <petr.tesarik1@...wei-partners.com>
>>>
>>> If a segmentation fault is caused by accessing an address in the vmalloc
>>> area, check that the target page is present.
>>>
>>> Currently, if the kernel hits a guard page in the vmalloc area, UML blindly
>>> assumes that the fault is caused by a stale mapping and will be fixed by
>>> flush_tlb_kernel_vm(). Unsurprisingly, if the fault is caused by accessing
>>> a guard page, no mapping is created, and when the faulting instruction is
>>> restarted, it will cause exactly the same fault again, effectively creating
>>> an infinite loop.
>> 
>> Ping. Any comment on this fix?
> 
> I don't think I have seen a reply from you. If you did comment, then
> your email has not reached me.
> 
> Please, can you confirm you have seen my patch?

Yes. I'm just way behind my maintainer schedule. :-/

Thanks,
//richard