[PATCH] arm64: mm: Increase MODULES_VSIZE to 512MB
Ard Biesheuvel
ardb at kernel.org
Sun Mar 26 10:35:26 PDT 2023
On Sun, 26 Mar 2023 at 19:08, Shanker Donthineni <sdonthineni at nvidia.com> wrote:
>
> The allocation of modules occurs in two regions: the first region
> MODULES_VSIZE (128MB) is shared with the core kernel, while the
> the second region (2GB) is shared with other vmalloc callers.
> Depending on the size of the core kernel, the 128MB region may
> quickly fill up after loading a few modules, causing the system
> to switch to the 2GB region.
How much module space are you actually using? This 128 MiB region is
not shared with vmalloc() so it should be dedicated to modules
entirely.
If you are doing EFI boot, you may need to following patch to ensure
that the 128 MiB region is actually the one being used.
commit 010338d729c1090036eb40d2a60b7b7bce2445b8
Author: Ard Biesheuvel <ardb at kernel.org>
Date: Thu Feb 23 21:41:01 2023 +0100
arm64: kaslr: don't pretend KASLR is enabled if offset < MIN_KIMG_ALIGN
> Unfortunately, even the 2GB region
> can run out of space if previously loaded modules and the other
> kernel subsystems consume the entire area, leaving no space for
> additional modules.
>
> This issue usually occurs when the system has a large number of
> CPU cores, PCIe host-brigde controllers, and I/O devices. For
> instance, the ECAM region of one host-bridge controller can use
> up to 256MB of vmalloc space, while eight controllers can occupy
> the entire 2GB.
>
> One potential solution to address this issue is to increase the
> size of the MODULES_VSIZE region to 512MB, which would enhance
> the system's ability to support a greater number of dynamically
> loaded modules and drivers.
>
> Signed-off-by: Shanker Donthineni <sdonthineni at nvidia.com>
> ---
>
> I am seeking your guidance and feedback on the proposed solution
> to address the module load failures, specifically regarding any
> potential side effects that I need to be aware of. Additionally,
> I would appreciate your suggestions on any alternative solutions
> to resolve the issue.
>
> On a NVIDIA T241 system with Ubuntu-22.04, hitting boot failures
> due to vmalloc/vmap allocation errors when loading modules.
> dmesg:
> [ 64.181308] ipmi_ssif: IPMI SSIF Interface driver
> [ 64.184494] usbcore: registered new interface driver r8152
> [ 64.242492] vmap allocation for size 393216 failed: use vmalloc=<size> to increase size
> [ 64.242499] systemd-udevd: vmalloc error: size 327680, vm_struct allocation failed, mode:0xcc0(GFP_KERNEL), nodemask=(null),cpuset=/,mems_allowed=0-3
> [ 64.242510] CPU: 32 PID: 2910 Comm: systemd-udevd Tainted: G OE 6.2-generic-64k
> [ 64.242513] Hardware name: NVIDIA T241, BIOS v1.1.0 2023-03-18T21:32:31+00:00
> [ 64.242515] Call trace:
> [ 64.242516] dump_backtrace+0xe0/0x130
> [ 64.242523] show_stack+0x20/0x60
> [ 64.242525] dump_stack_lvl+0x68/0x84
> [ 64.242530] dump_stack+0x18/0x34
> [ 64.242532] warn_alloc+0x11c/0x1b0
> [ 64.242537] __vmalloc_node_range+0xe0/0x20c
> [ 64.242540] module_alloc+0x118/0x160
> [ 64.242543] move_module+0x2c/0x190
> [ 64.242546] layout_and_allocate+0xfc/0x160
> [ 64.242548] load_module+0x260/0xbc4
> [ 64.242549] __do_sys_finit_module+0xac/0x130
> [ 64.242551] __arm64_sys_finit_module+0x28/0x34
> [ 64.242552] invoke_syscall+0x78/0x100
> [ 64.242553] el0_svc_common.constprop.0+0x170/0x194
> [ 64.242555] do_el0_svc+0x38/0x4c
> [ 64.242556] el0_svc+0x2c/0xc0
> [ 64.242558] el0t_64_sync_handler+0xbc/0x13c
> [ 64.242560] el0t_64_sync+0x1a0/0x1a4
>
> Documentation/arm64/memory.rst | 8 ++++----
> arch/arm64/include/asm/memory.h | 2 +-
> 2 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/arm64/memory.rst b/Documentation/arm64/memory.rst
> index 2a641ba7be3b..76c2fd8bbbf7 100644
> --- a/Documentation/arm64/memory.rst
> +++ b/Documentation/arm64/memory.rst
> @@ -33,8 +33,8 @@ AArch64 Linux memory layout with 4KB pages + 4 levels (48-bit)::
> 0000000000000000 0000ffffffffffff 256TB user
> ffff000000000000 ffff7fffffffffff 128TB kernel logical memory map
> [ffff600000000000 ffff7fffffffffff] 32TB [kasan shadow region]
> - ffff800000000000 ffff800007ffffff 128MB modules
> - ffff800008000000 fffffbffefffffff 124TB vmalloc
> + ffff800000000000 ffff80001fffffff 512MB modules
> + ffff800020000000 fffffbffefffffff 124TB vmalloc
> fffffbfff0000000 fffffbfffdffffff 224MB fixed mappings (top down)
> fffffbfffe000000 fffffbfffe7fffff 8MB [guard region]
> fffffbfffe800000 fffffbffff7fffff 16MB PCI I/O space
> @@ -50,8 +50,8 @@ AArch64 Linux memory layout with 64KB pages + 3 levels (52-bit with HW support):
> 0000000000000000 000fffffffffffff 4PB user
> fff0000000000000 ffff7fffffffffff ~4PB kernel logical memory map
> [fffd800000000000 ffff7fffffffffff] 512TB [kasan shadow region]
> - ffff800000000000 ffff800007ffffff 128MB modules
> - ffff800008000000 fffffbffefffffff 124TB vmalloc
> + ffff800000000000 ffff80001fffffff 512MB modules
> + ffff800020000000 fffffbffefffffff 124TB vmalloc
> fffffbfff0000000 fffffbfffdffffff 224MB fixed mappings (top down)
> fffffbfffe000000 fffffbfffe7fffff 8MB [guard region]
> fffffbfffe800000 fffffbffff7fffff 16MB PCI I/O space
> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
> index 78e5163836a0..dd5d634e235f 100644
> --- a/arch/arm64/include/asm/memory.h
> +++ b/arch/arm64/include/asm/memory.h
> @@ -46,7 +46,7 @@
> #define KIMAGE_VADDR (MODULES_END)
> #define MODULES_END (MODULES_VADDR + MODULES_VSIZE)
> #define MODULES_VADDR (_PAGE_END(VA_BITS_MIN))
> -#define MODULES_VSIZE (SZ_128M)
> +#define MODULES_VSIZE (SZ_512M)
> #define VMEMMAP_START (-(UL(1) << (VA_BITS - VMEMMAP_SHIFT)))
> #define VMEMMAP_END (VMEMMAP_START + VMEMMAP_SIZE)
> #define PCI_IO_END (VMEMMAP_START - SZ_8M)
> --
> 2.25.1
>
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