linux-kernel - Re: [RFC PATCH 2/2] lib, stackdepot: Add helper to print stack entries.

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Date:   Wed, 1 Sep 2021 11:07:37 +0200
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Imran Khan <imran.f.khan@...cle.com>, geert@...ux-m68k.org,
        akpm@...ux-foundation.org
Cc:     linux-kernel@...r.kernel.org,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        Alexander Potapenko <glider@...gle.com>
Subject: Re: [RFC PATCH 2/2] lib, stackdepot: Add helper to print stack
 entries.

On 9/1/21 07:19, Imran Khan wrote:
> To print a stack entries, users of stackdepot, first
> use stack_depot_fetch to get a list of stack entries
> and then use stack_trace_print to print this list.
> Provide a helper in stackdepot to print stack entries
> based on stackdepot handle.
> 
> Signed-off-by: Imran Khan <imran.f.khan@...cle.com>
> Suggested-by: Vlastimil Babka <vbabka@...e.cz>

You should convert existing users together with the patch that introduces
the helper. I think print_stack() in mm/kasan/report.c, and
__dump_page_owner() could use this.

> ---
>  lib/stackdepot.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)

It's missing a declaration in include/linux/stackdepot.h
Perhaps it could be all be a static inline there anyway.

> diff --git a/lib/stackdepot.c b/lib/stackdepot.c
> index 1d42ef9ef766..eab4476b060b 100644
> --- a/lib/stackdepot.c
> +++ b/lib/stackdepot.c
> @@ -214,6 +214,23 @@ static inline struct stack_record *find_stack(struct stack_record *bucket,
>  	return NULL;
>  }
>  
> +/**
> + * stack_depot_print - print stack entries from a depot
> + *
> + * @handle:		Stack depot handle which was returned from
> + *			stack_depot_save().
> + *
> + */
> +void stack_depot_print(depot_stack_handle_t stack)
> +{
> +	unsigned long *entries;
> +	unsigned int nr_entries;
> +
> +	nr_entries = stack_depot_fetch(stack, &entries);
> +	stack_trace_print(entries, nr_entries, 0);
> +}
> +EXPORT_SYMBOL_GPL(stack_depot_print);
> +
>  /**
>   * stack_depot_fetch - Fetch stack entries from a depot
>   *
>