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From: Mike Rapoport <rppt@kernel.org>
To: Faiyaz Mohammed <quic_faiyazm@quicinc.com>
Cc: quic_vjitta@quicinc.com, karahmed@amazon.de, qperret@google.com,
	robh@kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: memblock: avoid to create memmap for memblock nomap regions
Date: Tue, 12 Apr 2022 20:26:36 +0300	[thread overview]
Message-ID: <YlW2TO0O8qDHpkGW@kernel.org> (raw)
In-Reply-To: <1649704172-13181-1-git-send-email-quic_faiyazm@quicinc.com>

On Tue, Apr 12, 2022 at 12:39:32AM +0530, Faiyaz Mohammed wrote:
> This 'commit 86588296acbf ("fdt: Properly handle "no-map" field in the
> memory region")' is keeping the no-map regions in memblock.memory with
> MEMBLOCK_NOMAP flag set to use no-map memory for EFI using memblock api's,
> but during the initialization sparse_init mark all memblock.memory as
> present using for_each_mem_pfn_range, which is creating the memmap for
> no-map memblock regions. To avoid it skiping the memblock.memory regions
> set with MEMBLOCK_NOMAP set and with this change we will be able to save
> ~11MB memory for ~612MB carve out.

The MEMBLOCK_NOMAP is very fragile and caused a lot of issues already. I
really don't like the idea if adding more implicit assumptions about how
NOMAP memory may or may not be used in a generic iterator function.

-- 
Sincerely yours,
Mike.


  reply	other threads:[~2022-04-12 17:26 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-11 19:09 [PATCH] mm: memblock: avoid to create memmap for memblock nomap regions Faiyaz Mohammed
2022-04-12 17:26 ` Mike Rapoport [this message]
2022-05-05 15:16   ` Faiyaz Mohammed
2022-05-05 15:31     ` Rob Herring
2022-05-05 16:54     ` Mike Rapoport
2022-05-09 11:07       ` Faiyaz Mohammed
2022-05-09 11:42         ` Mike Rapoport
2022-08-03 10:57           ` Vijayanand Jitta
2022-08-05 19:22             ` Mike Rapoport
2024-02-08  6:37               ` Aiqun Yu (Maria)
2024-02-14  7:43                 ` Mike Rapoport
2024-02-14  8:11                   ` Dmitry Baryshkov
2024-02-14  9:15                     ` Mike Rapoport
2024-02-20  6:28                       ` Aiqun Yu (Maria)
2024-02-27 10:00                         ` Mike Rapoport

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