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From: Matthew Wilcox <willy@infradead.org>
To: Miaohe Lin <linmiaohe@huawei.com>
Cc: akpm@linux-foundation.org, vbabka@suse.cz, sfr@canb.auug.org.au,
	peterz@infradead.org, mgorman@techsingularity.net,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 6/6] mm/page_alloc.c: avoid allocating highmem pages via alloc_pages_exact_nid()
Date: Mon, 30 Aug 2021 15:24:14 +0100	[thread overview]
Message-ID: <YSzqDt/13YbOAyo4@casper.infradead.org> (raw)
In-Reply-To: <20210830141051.64090-7-linmiaohe@huawei.com>

On Mon, Aug 30, 2021 at 10:10:51PM +0800, Miaohe Lin wrote:
> Don't use with __GFP_HIGHMEM because page_address() cannot represent
> highmem pages without kmap(). Newly allocated pages would leak as
> page_address() will return NULL for highmem pages here. But It works
> now because the only caller does not specify __GFP_HIGHMEM now.

This is a misunderstanding of how alloc_pages_exact() /
alloc_pages_exact_nid() work.  You simply can't call them with
GFP_HIGHMEM.

If you really must change anything here,
s/__GFP_COMP/(__GFP_COMP|__GFP_HIGHMEM)/g throughout both
alloc_pages_exact() and alloc_pages_exact_nid().

  reply	other threads:[~2021-08-30 14:27 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-30 14:10 [PATCH 0/6] Cleanups and fixup for page_alloc Miaohe Lin
2021-08-30 14:10 ` [PATCH 1/6] mm/page_alloc.c: remove meaningless VM_BUG_ON() in pindex_to_order() Miaohe Lin
2021-08-31 13:34   ` Mel Gorman
2021-08-31 14:05   ` David Hildenbrand
2021-08-30 14:10 ` [PATCH 2/6] mm/page_alloc.c: simplify the code by using macro K() Miaohe Lin
2021-08-31  8:54   ` Oleksandr Natalenko
2021-08-31 11:08     ` Miaohe Lin
2021-08-31 14:19       ` Oleksandr Natalenko
2021-09-01  7:37         ` Miaohe Lin
2021-09-01  7:46           ` Oleksandr Natalenko
2021-09-01  8:17             ` Miaohe Lin
2021-09-01 21:25           ` David Laight
2021-09-02  6:32             ` Miaohe Lin
2021-08-31 13:35   ` Mel Gorman
2021-08-31 14:07   ` David Hildenbrand
2021-08-30 14:10 ` [PATCH 3/6] mm/page_alloc.c: remove obsolete comment in free_pcppages_bulk() Miaohe Lin
2021-08-31 13:38   ` Mel Gorman
2021-09-01  7:49     ` Miaohe Lin
2021-09-01 15:14       ` Mel Gorman
2021-09-02  6:25         ` Miaohe Lin
2021-08-30 14:10 ` [PATCH 4/6] mm/page_alloc.c: use helper function zone_spans_pfn() Miaohe Lin
2021-08-31 13:39   ` Mel Gorman
2021-08-31 14:08   ` David Hildenbrand
2021-08-30 14:10 ` [PATCH 5/6] mm/page_alloc.c: avoid accessing uninitialized pcp page migratetype Miaohe Lin
2021-08-31 13:43   ` Mel Gorman
2021-08-31 14:23     ` David Hildenbrand
2021-09-01  8:02       ` Miaohe Lin
2021-09-01  8:10         ` David Hildenbrand
2021-09-01  8:18           ` Miaohe Lin
2021-08-31 16:34     ` Vlastimil Babka
2021-09-01  8:04       ` Miaohe Lin
2021-08-30 14:10 ` [PATCH 6/6] mm/page_alloc.c: avoid allocating highmem pages via alloc_pages_exact_nid() Miaohe Lin
2021-08-30 14:24   ` Matthew Wilcox [this message]
2021-08-31  1:56     ` Miaohe Lin
2021-08-31 16:37       ` Vlastimil Babka
2021-09-01  8:05         ` Miaohe Lin

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