linux-kernel - Re: [PATCH 2/8] mm: Accept memory in __alloc_pages

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Message-ID: <2276d983-cb01-4a28-9f12-13ac924a7248@redhat.com>
Date: Tue, 6 Aug 2024 14:02:35 +0200
From: David Hildenbrand <david@...hat.com>
To: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 "Borislav Petkov (AMD)" <bp@...en8.de>, Mel Gorman <mgorman@...e.de>,
 Vlastimil Babka <vbabka@...e.cz>
Cc: Tom Lendacky <thomas.lendacky@....com>, Mike Rapoport <rppt@...nel.org>,
 "Matthew Wilcox (Oracle)" <willy@...radead.org>,
 Johannes Weiner <hannes@...xchg.org>, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/8] mm: Accept memory in __alloc_pages_bulk().

On 05.08.24 16:59, Kirill A. Shutemov wrote:
> Currently, the kernel only accepts memory in get_page_from_freelist(),
> but there is another path that directly takes pages from free lists -
> __alloc_page_bulk(). This function can consume all accepted memory and
> will resort to __alloc_pages_noprof() if necessary.
> 
> Conditionally accepted in __alloc_pages_bulk().
> 
> The same issue may arise due to deferred page initialization. Kick the
> deferred initialization machinery before abandoning the zone, as the
> kernel does in get_page_from_freelist().
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> ---
>   mm/page_alloc.c | 13 +++++++++++++
>   1 file changed, 13 insertions(+)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index aa9b1eaa638c..90a1f01d5996 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -4576,12 +4576,25 @@ unsigned long alloc_pages_bulk_noprof(gfp_t gfp, int preferred_nid,
>   			goto failed;
>   		}
>   
> +		cond_accept_memory(zone, 0);
> +retry_this_zone:
>   		mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK) + nr_pages;
>   		if (zone_watermark_fast(zone, 0,  mark,
>   				zonelist_zone_idx(ac.preferred_zoneref),
>   				alloc_flags, gfp)) {
>   			break;
>   		}
> +
> +		if (cond_accept_memory(zone, 0))
> +			goto retry_this_zone;
> +
> +#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
> +		/* Try again if zone has deferred pages */
> +		if (deferred_pages_enabled()) {
> +			if (_deferred_grow_zone(zone, 0))
> +				goto retry_this_zone;
> +		}
> +#endif

We could probably avoid the #ifdef if we add a dummy function for 
_deferred_grow_zone().

Same applies to the other similar users in this file.

Acked-by: David Hildenbrand <david@...hat.com>

-- 
Cheers,

David / dhildenb