From: Mike Rapoport <rppt@kernel.org>
To: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Huacai Chen <chenhuacai@kernel.org>,
linux-mm@kvack.org, loongarch@lists.linux.dev,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 2/2] LoongArch: mm: Expand modules virtual address space to 2GB
Date: Sun, 19 Jul 2026 12:01:53 +0300 [thread overview]
Message-ID: <alySgaaQen6ZtwSo@kernel.org> (raw)
In-Reply-To: <20260717075715.25513-3-yangtiezhu@loongson.cn>
Hi,
On Fri, Jul 17, 2026 at 03:57:15PM +0800, Tiezhu Yang wrote:
> Frequent "execmem: unable to allocate memory" warnings are observed
> during kernel module loading when updating the latest kernel.
>
> This is because the modules virtual address region on LoongArch is
> tightly constrained to 256MB, while ARM64 and RISC-V are natively
> configured with a spacious 2GB region.
The constraint follows architecture ability to address kernel instructions
and data from modules code.
I don't know what are loongarch requirements, but I remember that arm64
added a layer of relocation support to allow 2G module address space.
> Expand the modules virtual address space to 2GB for LoongArch to
> eliminate these allocation bottlenecks.
>
> This change only applies to 64-bit kernels (CONFIG_64BIT), 32-bit
> kernels (CONFIG_32BIT) are entirely unaffected since they do not
> define separate module address regions.
>
> With this patch, there are no "execmem: unable to allocate memory"
> warnings anymore for 64-bit kernels.
>
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> ---
> arch/loongarch/include/asm/pgtable.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h
> index 223528c04d73..e5952ecd6a73 100644
> --- a/arch/loongarch/include/asm/pgtable.h
> +++ b/arch/loongarch/include/asm/pgtable.h
> @@ -96,7 +96,7 @@ struct vm_area_struct;
> #ifdef CONFIG_64BIT
>
> #define MODULES_VADDR (vm_map_base + PCI_IOSIZE + (2 * PAGE_SIZE))
> -#define MODULES_END (MODULES_VADDR + SZ_256M)
> +#define MODULES_END (MODULES_VADDR + SZ_2G)
>
> #ifdef CONFIG_KFENCE
> #define KFENCE_AREA_SIZE (((CONFIG_KFENCE_NUM_OBJECTS + 1) * 2 + 2) * PAGE_SIZE)
> --
> 2.42.0
>
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2026-07-19 9:01 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-17 7:57 [PATCH v1 0/2] Enhance execmem diagnostic and fix LoongArch module bottleneck Tiezhu Yang
2026-07-17 7:57 ` [PATCH v1 1/2] mm/execmem: Print size, align and caller on allocation failure Tiezhu Yang
2026-07-17 18:37 ` Andrew Morton
2026-07-19 8:55 ` Mike Rapoport
2026-07-17 7:57 ` [PATCH v1 2/2] LoongArch: mm: Expand modules virtual address space to 2GB Tiezhu Yang
2026-07-19 9:01 ` Mike Rapoport [this message]
2026-07-19 15:28 ` Xi Ruoyao
2026-07-20 7:16 ` Tiezhu Yang
2026-07-20 10:40 ` Tiezhu Yang
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