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

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Message-ID: <6a62f534-463f-45c4-a5ea-2c1021cf45d4@huaweicloud.com>
Date: Wed, 20 Mar 2024 14:58:59 +0100
From: Petr Tesarik <petrtesarik@...weicloud.com>
To: Richard Weinberger <richard@....at>
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

On 3/19/2024 11:18 PM, Richard Weinberger wrote:
> ----- 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. :-/

Understood. Thank you for your reply.

By the way, are you looking for more people to help with the amount of work?

Petr T