linux-kernel - Re: [PATCH] mm: ALLOC_HIGHATOMIC flag allocation issue

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Message-ID: <ZVuXlcwgcw0ShjRQ@casper.infradead.org>
Date:   Mon, 20 Nov 2023 17:29:57 +0000
From:   Matthew Wilcox <willy@...radead.org>
To:     Zhiguo Jiang <justinjiang@...o.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Johannes Weiner <hannes@...xchg.org>,
        opensource.kernel@...o.com
Subject: Re: [PATCH] mm: ALLOC_HIGHATOMIC flag allocation issue

On Mon, Nov 20, 2023 at 10:35:36AM +0800, Zhiguo Jiang wrote:
> +			/*
> +			 * If pcplist is empty and alloc_flags is with ALLOC_HIGHATOMIC,
> +			 * it should alloc from buddy highatomic migrate freelist firstly
> +			 * to ensure quick and successful allocation.

Assuming that all the serious question shave been dealt with, let's
fix the less important problems ...

			 * If pcplist is empty and alloc_flags contains
			 * ALLOC_HIGHATOMIC, alloc from buddy highatomic
			 * freelist first.

> @@ -2918,7 +2927,7 @@ static inline
>  struct page *rmqueue(struct zone *preferred_zone,
>  			struct zone *zone, unsigned int order,
>  			gfp_t gfp_flags, unsigned int alloc_flags,
> -			int migratetype)
> +			int migratetype, bool *highatomc_allocation)

bool *highatomic

> +	/*
> +	 * The high-order atomic allocation pageblock reserved conditions:
> +	 *
> +	 * If the high-order atomic allocation page is alloced from pcplist,
> +	 * the highatomic pageblock does not need to be reserved, which can
> +	 * void to migrate an increasing number of pages into buddy

	 * avoid migrating an increasing number of pages into buddy

> +	 * MIGRATE_HIGHATOMIC freelist and lead to an increasing risk of

"increased"

> +	 * allocation failure on other buddy migrate freelists.
> +	 *
> +	 * If the high-order atomic allocation page is alloced from buddy

"allocated"

> @@ -3208,6 +3234,7 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
>  	struct pglist_data *last_pgdat = NULL;
>  	bool last_pgdat_dirty_ok = false;
>  	bool no_fallback;
> +	bool highatomc_allocation = false;

Again, just call this 'highatomic'.