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From: Matthew Wilcox <willy@infradead.org>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: linux-mm@kvack.org, akpm@linux-foundation.org,
	Vlastimil Babka <vbabka@suse.cz>,
	Randy Dunlap <rdunlap@infradead.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH V2] mm/thp: Make ALLOC_SPLIT_PTLOCKS dependent on USE_SPLIT_PTE_PTLOCKS
Date: Thu, 20 May 2021 12:17:24 +0100	[thread overview]
Message-ID: <YKZFRPqg4wKjOdVg@casper.infradead.org> (raw)
In-Reply-To: <1621409586-5555-1-git-send-email-anshuman.khandual@arm.com>

On Wed, May 19, 2021 at 01:03:06PM +0530, Anshuman Khandual wrote:
> Split ptlocks need not be defined and allocated unless they are being used.
> ALLOC_SPLIT_PTLOCKS is inherently dependent on USE_SPLIT_PTE_PTLOCKS. This
> just makes it explicit and clear. While here drop the spinlock_t element
> from the struct page when USE_SPLIT_PTE_PTLOCKS is not enabled.

I didn't spot this email yesterday.  I'm not a fan.  Isn't struct page
already complicated enough without adding another ifdef to it?  Surely
there's a better way than this.

> +++ b/include/linux/mm_types.h
> @@ -152,10 +152,12 @@ struct page {
>  				struct mm_struct *pt_mm; /* x86 pgds only */
>  				atomic_t pt_frag_refcount; /* powerpc */
>  			};
> +#if USE_SPLIT_PTE_PTLOCKS
>  #if ALLOC_SPLIT_PTLOCKS
>  			spinlock_t *ptl;
>  #else
>  			spinlock_t ptl;
> +#endif
>  #endif
>  		};
>  		struct {	/* ZONE_DEVICE pages */

  reply	other threads:[~2021-05-20 12:24 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-19  7:33 [PATCH V2] mm/thp: Make ALLOC_SPLIT_PTLOCKS dependent on USE_SPLIT_PTE_PTLOCKS Anshuman Khandual
2021-05-20 11:17 ` Matthew Wilcox [this message]
2021-07-01  5:21   ` Anshuman Khandual
2021-07-01 12:57     ` Matthew Wilcox
2021-07-05  3:27       ` Anshuman Khandual
2021-07-05  3:28         ` Matthew Wilcox
2021-07-05  3:39           ` Anshuman Khandual
2021-07-05 11:30             ` Matthew Wilcox

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