From: Sam Ravnborg <sam@ravnborg.org>
To: Dawei Li <dawei.li@shingroup.cn>
Cc: davem@davemloft.net, andreas@gaisler.com,
sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 5/7] sparc: Remove on-stack cpumask var
Date: Sat, 20 Apr 2024 10:28:05 +0200 [thread overview]
Message-ID: <20240420082805.GE614130@ravnborg.org> (raw)
In-Reply-To: <20240420051547.3681642-6-dawei.li@shingroup.cn>
On Sat, Apr 20, 2024 at 01:15:45PM +0800, Dawei Li wrote:
> In general it's preferable to avoid placing cpumasks on the stack, as
> for large values of NR_CPUS these can consume significant amounts of
> stack space and make stack overflows more likely.
>
> Since the cpumask var resides in __init function, which means it's free
> of any concurrenct access, it can be safely marked with static to get
> rid of allocation on stack.
>
> while at it, mark it with __initdata to keep it from persistently
> consumed memory.
I do not see the need for this - it does not fix a bug and it
complicates things.
If the size is a real concern the normal pattern is to allocate
and not declare it __initdata.
Yes - __initdata is used in some place.
I suggest to leave it as is unless we are fixing a real bug here.
Sam
>
> Signed-off-by: Dawei Li <dawei.li@shingroup.cn>
> ---
> arch/sparc/mm/init_64.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
> index 1ca9054d9b97..088d9c103dcc 100644
> --- a/arch/sparc/mm/init_64.c
> +++ b/arch/sparc/mm/init_64.c
> @@ -1438,7 +1438,7 @@ static int __init numa_attach_mlgroup(struct mdesc_handle *md, u64 grp,
> static int __init numa_parse_mdesc_group(struct mdesc_handle *md, u64 grp,
> int index)
> {
> - cpumask_t mask;
> + static cpumask_t mask __initdata;
> int cpu;
>
> numa_parse_mdesc_group_cpus(md, grp, &mask);
> --
> 2.27.0
next prev parent reply other threads:[~2024-04-20 8:28 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-20 5:15 [PATCH v2 0/7] Remove onstack cpumask var for sparc Dawei Li
2024-04-20 5:15 ` [PATCH v2 1/7] sparc/srmmu: Remove on-stack cpumask var Dawei Li
2024-04-20 7:58 ` Sam Ravnborg
2024-04-22 5:46 ` Dawei Li
2024-04-20 5:15 ` [PATCH v2 2/7] sparc/irq: " Dawei Li
2024-04-20 8:22 ` Sam Ravnborg
2024-04-20 5:15 ` [PATCH v2 3/7] sparc/of: " Dawei Li
2024-04-20 8:23 ` Sam Ravnborg
2024-04-20 5:15 ` [PATCH v2 4/7] sparc/pci_msi: " Dawei Li
2024-04-20 8:23 ` Sam Ravnborg
2024-04-20 5:15 ` [PATCH v2 5/7] sparc: " Dawei Li
2024-04-20 8:28 ` Sam Ravnborg [this message]
2024-04-22 5:49 ` Dawei Li
2024-04-20 5:15 ` [PATCH v2 6/7] sparc/leon: " Dawei Li
2024-04-20 8:32 ` Sam Ravnborg
2024-04-22 6:15 ` Dawei Li
2024-04-20 5:15 ` [PATCH v2 7/7] sparc/smp: " Dawei Li
2024-04-20 11:42 ` Sam Ravnborg
2024-04-22 6:19 ` Dawei Li
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