From: Will Deacon <will@kernel.org>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Barry Song <song.bao.hua@hisilicon.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
linuxarm@huawei.com, linux-mm@kvack.org,
Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Jonathan Cameron <jonathan.cameron@huawei.com>,
"H.Peter Anvin" <hpa@zytor.com>, Borislav Petkov <bp@alien8.de>,
akpm@linux-foundation.org, Mike Rapoport <rppt@linux.ibm.com>,
Roman Gushchin <guro@fb.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3] mm/hugetlb: split hugetlb_cma in nodes with memory
Date: Wed, 15 Jul 2020 09:18:22 +0100 [thread overview]
Message-ID: <20200715081822.GA5683@willie-the-truck> (raw)
In-Reply-To: <359ea1d0-b1fd-d09f-d28a-a44655834277@oracle.com>
Hi Mike,
On Tue, Jul 14, 2020 at 04:21:01PM -0700, Mike Kravetz wrote:
> I agree we should only be concerned with N_MEMORY nodes for the CMA
> reservations. However, this patch got me thinking:
> - Do we really have to initiate the CMA reservations from arch specific code?
> - Can we move the call to reserve CMA a little later into hugetlb arch
> independent code?
>
> I know the cma_declare_contiguous_nid() routine says it should be called
> from arch specific code. However, unless I am missing something that seems
> mostly about timing.
>
> What about a change like this on top of this patch?
>
> From 72b5b9a623f8711ad7f79f1a8f910906245f5d07 Mon Sep 17 00:00:00 2001
> From: Mike Kravetz <mike.kravetz@oracle.com>
> Date: Tue, 14 Jul 2020 15:54:46 -0700
> Subject: [PATCH] hugetlb: move cma allocation call to arch independent code
>
> Instead of calling hugetlb_cma_reserve() from arch specific code,
> call from arch independent code when a gigantic page hstate is
> created. This is late enough in the init process that all numa
> memory information should be initialized. And, it is early enough
> to still use early memory allocator.
>
> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
> ---
> arch/arm64/mm/init.c | 10 ----------
> arch/x86/kernel/setup.c | 9 ---------
> mm/hugetlb.c | 8 +++++++-
> 3 files changed, 7 insertions(+), 20 deletions(-)
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 79806732f4b4..ff0ff584dde9 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -427,16 +427,6 @@ void __init bootmem_init(void)
> sparse_init();
> zone_sizes_init(min, max);
>
> - /*
> - * must be done after zone_sizes_init() which calls free_area_init()
> - * that calls node_set_state() to initialize node_states[N_MEMORY]
> - * because hugetlb_cma_reserve() will scan over nodes with N_MEMORY
> - * state
> - */
> -#ifdef CONFIG_ARM64_4K_PAGES
> - hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
> -#endif
> -
> memblock_dump_all();
> }
>
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index a1a9712090ae..111c8467fafa 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -1177,15 +1177,6 @@ void __init setup_arch(char **cmdline_p)
>
> x86_init.paging.pagetable_init();
>
> - /*
> - * must be done after zone_sizes_init() which calls free_area_init()
> - * that calls node_set_state() to initialize node_states[N_MEMORY]
> - * because hugetlb_cma_reserve() will scan over nodes with N_MEMORY
> - * state
> - */
> - if (boot_cpu_has(X86_FEATURE_GBPAGES))
> - hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
> -
> kasan_init();
>
> /*
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index f24acb3af741..a0007d1d12d2 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -3273,6 +3273,9 @@ void __init hugetlb_add_hstate(unsigned int order)
> snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
> huge_page_size(h)/1024);
(nit: you can also make hugetlb_cma_reserve() static and remote its function
prototypes from hugetlb.h)
> + if (order >= MAX_ORDER && hugetlb_cma_size)
> + hugetlb_cma_reserve(order);
Although I really like the idea of moving this out of the arch code, I don't
quite follow the check against MAX_ORDER here -- it looks like a bit of a
hack to try to intercept the "PUD_SHIFT - PAGE_SHIFT" order which we
currently pass to hugetlb_cma_reserve(). Maybe we could instead have
something like:
#ifndef HUGETLB_CMA_ORDER
#define HUGETLB_CMA_ORDER (PUD_SHIFT - PAGE_SHIFT)
#endif
and then just do:
if (order == HUGETLB_CMA_ORDER)
hugetlb_cma_reserve(order);
? Is there something else I'm missing?
> +
> parsed_hstate = h;
> }
>
> @@ -5647,7 +5650,10 @@ void __init hugetlb_cma_reserve(int order)
> unsigned long size, reserved, per_node;
> int nid;
>
> - cma_reserve_called = true;
> + if (cma_reserve_called)
> + return;
> + else
> + cma_reserve_called = true;
(nit: don't need the 'else' here)
Will
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next prev parent reply other threads:[~2020-07-15 8:47 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-10 12:09 [PATCH v3] mm/hugetlb: split hugetlb_cma in nodes with memory Barry Song
2020-07-14 23:21 ` Mike Kravetz
2020-07-15 8:18 ` Will Deacon [this message]
2020-07-15 16:59 ` Mike Kravetz
2020-07-16 8:12 ` Will Deacon
[not found] ` <a867c7a2-e89b-2015-4895-f30f7aeb07cb@oracle.com>
2020-07-17 5:02 ` Anshuman Khandual
2020-07-17 8:36 ` Will Deacon
2020-07-17 9:51 ` Anshuman Khandual
[not found] ` <c2e4d47b-940b-481c-c155-a34c3e853e85@oracle.com>
2020-07-20 6:14 ` Anshuman Khandual
2020-07-17 17:02 ` Mike Kravetz
2020-07-20 6:22 ` Anshuman Khandual
2020-07-20 18:17 ` Mike Kravetz
2020-07-27 14:37 ` Aneesh Kumar K.V
2020-07-27 17:52 ` Mike Kravetz
2020-07-15 11:14 ` Song Bao Hua (Barry Song)
2020-07-15 17:05 ` Mike Kravetz
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