linux-kernel - Re: [PATCH v2 1/1] alloc_tag: mark pages reserved during CMA activation as not tagged

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Message-ID: <471af0a8-92fc-4fe0-85e4-193d713d4e57@redhat.com>
Date: Tue, 13 Aug 2024 11:25:19 +0200
From: David Hildenbrand <david@...hat.com>
To: Suren Baghdasaryan <surenb@...gle.com>, akpm@...ux-foundation.org
Cc: kent.overstreet@...ux.dev, vbabka@...e.cz, pasha.tatashin@...een.com,
 souravpanda@...gle.com, keescook@...omium.org, linux-kernel@...r.kernel.org,
 linux-mm@...ck.org, stable@...r.kernel.org
Subject: Re: [PATCH v2 1/1] alloc_tag: mark pages reserved during CMA
 activation as not tagged

On 12.08.24 21:24, Suren Baghdasaryan wrote:
> During CMA activation, pages in CMA area are prepared and then freed
> without being allocated. This triggers warnings when memory allocation
> debug config (CONFIG_MEM_ALLOC_PROFILING_DEBUG) is enabled. Fix this
> by marking these pages not tagged before freeing them.
> 
> Fixes: d224eb0287fb ("codetag: debug: mark codetags for reserved pages as empty")
> Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
> Cc: stable@...r.kernel.org # v6.10
> ---
> changes since v1 [1]
> - Added Fixes tag
> - CC'ed stable
> 
> [1] https://lore.kernel.org/all/20240812184455.86580-1-surenb@google.com/
> 
>   mm/mm_init.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/mm/mm_init.c b/mm/mm_init.c
> index 75c3bd42799b..ec9324653ad9 100644
> --- a/mm/mm_init.c
> +++ b/mm/mm_init.c
> @@ -2245,6 +2245,16 @@ void __init init_cma_reserved_pageblock(struct page *page)
>   
>   	set_pageblock_migratetype(page, MIGRATE_CMA);
>   	set_page_refcounted(page);
> +
> +	/* pages were reserved and not allocated */
> +	if (mem_alloc_profiling_enabled()) {
> +		union codetag_ref *ref = get_page_tag_ref(page);
> +
> +		if (ref) {
> +			set_codetag_empty(ref);
> +			put_page_tag_ref(ref);
> +		}
> +	}

Should we have a helper like clear_page_tag_ref() that wraps this?

-- 
Cheers,

David / dhildenb