From: Matthew Wilcox <willy@infradead.org>
To: Gavin Shan <gshan@redhat.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
akpm@linux-foundation.org, william.kucharski@oracle.com,
david@redhat.com, ryan.roberts@arm.com, shan.gavin@gmail.com
Subject: Re: [PATCH] mm/huge_memory: Avoid PMD-size page cache if needed
Date: Thu, 11 Jul 2024 21:46:56 +0100 [thread overview]
Message-ID: <ZpBEwEn3swH7IFbI@casper.infradead.org> (raw)
In-Reply-To: <20240711104840.200573-1-gshan@redhat.com>
On Thu, Jul 11, 2024 at 08:48:40PM +1000, Gavin Shan wrote:
> +++ b/mm/huge_memory.c
> @@ -136,7 +136,8 @@ unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma,
>
> while (orders) {
> addr = vma->vm_end - (PAGE_SIZE << order);
> - if (thp_vma_suitable_order(vma, addr, order))
> + if (!(vma->vm_file && order > MAX_PAGECACHE_ORDER) &&
> + thp_vma_suitable_order(vma, addr, order))
> break;
Why does 'orders' even contain potential orders that are larger than
MAX_PAGECACHE_ORDER?
We do this at the top:
orders &= vma_is_anonymous(vma) ?
THP_ORDERS_ALL_ANON : THP_ORDERS_ALL_FILE;
include/linux/huge_mm.h:#define THP_ORDERS_ALL_FILE (BIT(PMD_ORDER) | BIT(PUD_ORDER))
... and that seems very wrong. We support all kinds of orders for
files, not just PMD order. We don't support PUD order at all.
What the hell is going on here?
next parent reply other threads:[~2024-07-11 20:47 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20240711104840.200573-1-gshan@redhat.com>
2024-07-11 20:46 ` Matthew Wilcox [this message]
2024-07-11 21:03 ` [PATCH] mm/huge_memory: Avoid PMD-size page cache if needed David Hildenbrand
2024-07-11 21:20 ` David Hildenbrand
2024-07-12 5:39 ` Gavin Shan
2024-07-13 1:03 ` David Hildenbrand
2024-07-13 4:01 ` Baolin Wang
2024-07-13 4:17 ` David Hildenbrand
2024-07-13 12:57 ` Baolin Wang
2024-07-13 9:25 ` Gavin Shan
2024-07-13 11:05 ` Ryan Roberts
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