From: Ard Biesheuvel <ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
To: Robert Richter <robert.richter-YGCgFSpz5w/QT0dZR+AlfA@public.gmane.org>
Cc: Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>,
Robert Richter <rric-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>,
Catalin Marinas <catalin.marinas-5wv7dgnIgG8@public.gmane.org>,
David Daney <david.daney-YGCgFSpz5w/QT0dZR+AlfA@public.gmane.org>,
Hanjun Guo <hanjun.guo-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
"linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org"
<linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>,
"linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [PATCH] arm64: mm: Fix memmap to be initialized for the entire section
Date: Thu, 24 Nov 2016 13:44:31 +0000 [thread overview]
Message-ID: <CAKv+Gu_Ug3XOD6jy5xziy1pS7WV=TC0RLD4j3DT6nytujQDzRQ@mail.gmail.com> (raw)
In-Reply-To: <20161124134238.GI10776-vWBEXY7mpu582hYKe6nXyg@public.gmane.org>
On 24 November 2016 at 13:42, Robert Richter <robert.richter-YGCgFSpz5w/QT0dZR+AlfA@public.gmane.org> wrote:
> On 23.11.16 21:25:06, Ard Biesheuvel wrote:
>> Why? MEMREMAP_WB is used often, among other things for mapping
>> firmware tables, which are marked as NOMAP, so in these cases, the
>> linear address is not mapped.
>
> If fw tables are mapped wb, that is wrong and needs a separate fix.
>
Why is that wrong?
>> > If you think pfn_valid() is wrong here, I am happy to send a patch
>> > that fixes this by using page_is_ram(). In any case, the worst case
>> > that may happen is to behave the same as v4.4, we might fix then the
>> > wrong use of pfn_valid() where it is not correctly used to check for
>> > ram.
>> >
>>
>> page_is_ram() uses string comparisons to look for regions called
>> 'System RAM'. Is that something we can tolerate for each pfn_valid()
>> calll?
>>
>> Perhaps the solution is to reimplement page_is_ram() for arm64 using
>> memblock_is_memory() instead, But that still means we need to modify
>> the generic memremap() code first to switch to it before changing the
>> arm64 implementation of pfn_valid
>
> No, that's not the solution. pfn_valid() should just check if there is
> a valid struct page, as other archs do. And if there is a mis-use of
> pfn_valid() to check for ram, only that calls should be fixed to use
> page_is_ram(), however this is implemented, or something appropriate.
> But I don't see any problematic code, and if so, I will fix that.
>
memremap() uses pfn_valid() to decide whether some address is covered
by the linear mapping. If we correct pfn_valid() to adhere to your
definition, we will need to fix memremap() first in any case.
next prev parent reply other threads:[~2016-11-24 13:44 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-06 9:52 [PATCH] arm64: mm: Fix memmap to be initialized for the entire section Robert Richter
2016-10-10 15:33 ` David Daney
[not found] ` <1475747527-32387-1-git-send-email-rrichter-YGCgFSpz5w/QT0dZR+AlfA@public.gmane.org>
2016-10-06 10:00 ` Ard Biesheuvel
[not found] ` <CAKv+Gu-oYzSn_eeqaX3QVFeQjBGkaX-Wh7+oPcQFcXv7J6GOFQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-10-06 16:11 ` Robert Richter
[not found] ` <20161006161114.GH22012-vWBEXY7mpu582hYKe6nXyg@public.gmane.org>
2016-10-17 18:58 ` Robert Richter
[not found] ` <20161017185801.GT25086-vWBEXY7mpu582hYKe6nXyg@public.gmane.org>
2016-10-27 16:01 ` Will Deacon
[not found] ` <20161027160136.GD24290-5wv7dgnIgG8@public.gmane.org>
2016-10-28 9:19 ` Robert Richter
2016-11-07 21:05 ` Will Deacon
2016-11-09 19:51 ` Robert Richter
[not found] ` <20161109195132.GZ22012-vWBEXY7mpu582hYKe6nXyg@public.gmane.org>
2016-11-17 14:25 ` Will Deacon
2016-11-17 15:18 ` Robert Richter
[not found] ` <20161117151805.GJ2151-vWBEXY7mpu582hYKe6nXyg@public.gmane.org>
2016-11-20 17:07 ` Ard Biesheuvel
2016-11-23 21:15 ` Robert Richter
[not found] ` <20161123211538.GH10776-vWBEXY7mpu582hYKe6nXyg@public.gmane.org>
2016-11-23 21:25 ` Ard Biesheuvel
2016-11-24 13:42 ` Robert Richter
[not found] ` <20161124134238.GI10776-vWBEXY7mpu582hYKe6nXyg@public.gmane.org>
2016-11-24 13:44 ` Ard Biesheuvel [this message]
2016-11-24 13:51 ` Robert Richter
[not found] ` <20161124135151.GJ10776-vWBEXY7mpu582hYKe6nXyg@public.gmane.org>
2016-11-24 13:58 ` Ard Biesheuvel
2016-11-24 14:11 ` Robert Richter
2016-11-24 14:23 ` Ard Biesheuvel
2016-11-24 15:09 ` Robert Richter
[not found] ` <20161124150918.GF2213-vWBEXY7mpu582hYKe6nXyg@public.gmane.org>
2016-11-24 19:26 ` Robert Richter
2016-11-24 19:42 ` Ard Biesheuvel
[not found] ` <CAKv+Gu_C_17RtAiw2U0OOzVik3G7KkwUTo5eiGK-HDo-maQ-bA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-11-25 11:29 ` Robert Richter
[not found] ` <20161125112914.GI2213-vWBEXY7mpu582hYKe6nXyg@public.gmane.org>
2016-11-25 12:28 ` Ard Biesheuvel
2016-11-25 17:01 ` Ard Biesheuvel
2016-10-18 10:18 ` Mark Rutland
2016-10-18 15:02 ` Robert Richter
2016-11-01 16:55 ` Robert Richter
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