linux-kernel - Re: [PATCH v3 31/35] lib: add memory allocations report in show

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Message-ID: <Zc3X8XlnrZmh2mgN@tiehlicka>
Date: Thu, 15 Feb 2024 10:22:57 +0100
From: Michal Hocko <mhocko@...e.com>
To: Suren Baghdasaryan <surenb@...gle.com>
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Subject: Re: [PATCH v3 31/35] lib: add memory allocations report in show_mem()

On Mon 12-02-24 13:39:17, Suren Baghdasaryan wrote:
[...]
> @@ -423,4 +424,18 @@ void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx)
>  #ifdef CONFIG_MEMORY_FAILURE
>  	printk("%lu pages hwpoisoned\n", atomic_long_read(&num_poisoned_pages));
>  #endif
> +#ifdef CONFIG_MEM_ALLOC_PROFILING
> +	{
> +		struct seq_buf s;
> +		char *buf = kmalloc(4096, GFP_ATOMIC);
> +
> +		if (buf) {
> +			printk("Memory allocations:\n");
> +			seq_buf_init(&s, buf, 4096);
> +			alloc_tags_show_mem_report(&s);
> +			printk("%s", buf);
> +			kfree(buf);
> +		}
> +	}
> +#endif

I am pretty sure I have already objected to this. Memory allocations in
the oom path are simply no go unless there is absolutely no other way
around that. In this case the buffer could be preallocated.

-- 
Michal Hocko
SUSE Labs