From: DaeRo Lee <skseofh@gmail.com>
To: Mike Rapoport <rppt@kernel.org>
Cc: robh@kernel.org, saravanak@google.com, akpm@linux-foundation.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, Daero Lee <daero_le.lee@samsung.com>
Subject: Re: [PATCH v2] memblock: add no-map alloc functions
Date: Thu, 18 Apr 2024 23:54:15 +0900 [thread overview]
Message-ID: <CAATEi5kywwC2yUaYjgs+Gm=4HM5o=KHTqH1ALKJijWE_gge0=g@mail.gmail.com> (raw)
In-Reply-To: <Zh9l_LpThq9aFUR7@kernel.org>
2024년 4월 17일 (수) 오후 3:03, Mike Rapoport <rppt@kernel.org>님이 작성:
>
> On Tue, Apr 16, 2024 at 09:06:35PM +0900, skseofh@gmail.com wrote:
> > From: Daero Lee <daero_le.lee@samsung.com>
> >
> > Like reserved-memory with the 'no-map' property and only 'size' property
> > (w/o 'reg' property), there are memory regions need to be allocated in
> > memblock.memory marked with the MEMBLOCK_NOMAP flag, but should not be
> > allocated in memblock.reserved.
>
> This still does not explain why you need such regions.
>
> As Wei Yang explained, memblock does not allocate memory from
> memblock.reserved. The memblock.reserved array represents memory that is in
> use by firmware or by early kernel allocations and cannot be freed to page
> allocator.
Thank you for your comments. I used the wrong word.
When I use 'allocate', I mean that the region 'adds' to the memblock.reserved.
>
> If you have a region that's _NOMAP in memblock.memory and is absent in
> memblock.reserved it will not be mapped by the kernel page tables, but it
> will be considered as free memory by the core mm.
>
> Is this really what you want?
If my understanding is right, before freeing (memory && !reserved)
area, we marked the memblock.reserved regions and memblock.memory
regions with no-map flag. And when we free (memory && !reserved) area,
we skip the memblock.memory regions with no-map(see
should_skip_region). So, I think that the memory regions with no-map
flag will not be considered as free memory.
If there is anything I think is wrong, feel free to correct me.
Regards,
DaeRo Lee
next prev parent reply other threads:[~2024-04-18 14:54 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-16 12:06 [PATCH v2] memblock: add no-map alloc functions skseofh
2024-04-16 12:06 ` skseofh
2024-04-17 2:23 ` Wei Yang
2024-04-17 6:02 ` Mike Rapoport
2024-04-18 14:54 ` DaeRo Lee [this message]
2024-04-18 18:03 ` Mike Rapoport
2024-04-19 1:46 ` DaeRo Lee
2024-04-19 1:59 ` DaeRo Lee
2024-04-27 2:42 ` DaeRo Lee
2024-04-27 3:27 ` DaeRo Lee
2024-04-27 8:49 ` Mike Rapoport
2024-04-27 10:24 ` DaeRo Lee
2024-04-28 6:33 ` Mike Rapoport
2024-04-28 10:36 ` DaeRo Lee
2024-04-28 12:00 ` Mike Rapoport
2024-04-28 12:52 ` DaeRo Lee
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