From: David Hildenbrand <david@redhat.com>
To: Miaohe Lin <linmiaohe@huawei.com>, akpm@linux-foundation.org
Cc: 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 v2 5/5] mm/page_alloc.c: avoid allocating highmem pages via alloc_pages_exact[_nid]
Date: Thu, 2 Sep 2021 14:16:16 +0200 [thread overview]
Message-ID: <1ef3dc5d-7eb9-90a5-afbf-f551afcf7d8b@redhat.com> (raw)
In-Reply-To: <20210902121242.41607-6-linmiaohe@huawei.com>
On 02.09.21 14:12, 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 callers do not specify __GFP_HIGHMEM now.
>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
> mm/page_alloc.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 9c09dcb24149..e1d0e27d005a 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5614,8 +5614,8 @@ void *alloc_pages_exact(size_t size, gfp_t gfp_mask)
> unsigned int order = get_order(size);
> unsigned long addr;
>
> - if (WARN_ON_ONCE(gfp_mask & __GFP_COMP))
> - gfp_mask &= ~__GFP_COMP;
> + if (WARN_ON_ONCE(gfp_mask & (__GFP_COMP | __GFP_HIGHMEM)))
> + gfp_mask &= ~(__GFP_COMP | __GFP_HIGHMEM);
>
> addr = __get_free_pages(gfp_mask, order);
> return make_alloc_exact(addr, order, size);
> @@ -5639,8 +5639,8 @@ void * __meminit alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask)
> unsigned int order = get_order(size);
> struct page *p;
>
> - if (WARN_ON_ONCE(gfp_mask & __GFP_COMP))
> - gfp_mask &= ~__GFP_COMP;
> + if (WARN_ON_ONCE(gfp_mask & (__GFP_COMP | __GFP_HIGHMEM)))
> + gfp_mask &= ~(__GFP_COMP | __GFP_HIGHMEM);
>
> p = alloc_pages_node(nid, gfp_mask, order);
> if (!p)
>
Ideally we would convert this WARN_ON_ONCE() to pr_warn_once(), but I
guess this really never ever happens on a production system and would
get caught early while testing.
Reviewed-by: David Hildenbrand <david@redhat.com>
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2021-09-02 12:16 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-02 12:12 [PATCH v2 0/5] Cleanups and fixup for page_alloc Miaohe Lin
2021-09-02 12:12 ` [PATCH v2 1/5] mm/page_alloc.c: remove meaningless VM_BUG_ON() in pindex_to_order() Miaohe Lin
2021-09-02 12:12 ` [PATCH v2 2/5] mm/page_alloc.c: simplify the code by using macro K() Miaohe Lin
2021-09-02 12:12 ` [PATCH v2 3/5] mm/page_alloc.c: fix obsolete comment in free_pcppages_bulk() Miaohe Lin
2021-09-02 14:03 ` Mel Gorman
2021-09-02 12:12 ` [PATCH v2 4/5] mm/page_alloc.c: use helper function zone_spans_pfn() Miaohe Lin
2021-09-02 12:12 ` [PATCH v2 5/5] mm/page_alloc.c: avoid allocating highmem pages via alloc_pages_exact[_nid] Miaohe Lin
2021-09-02 12:16 ` David Hildenbrand [this message]
2021-09-02 12:45 ` Miaohe Lin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1ef3dc5d-7eb9-90a5-afbf-f551afcf7d8b@redhat.com \
--to=david@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=linmiaohe@huawei.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@techsingularity.net \
--cc=peterz@infradead.org \
--cc=sfr@canb.auug.org.au \
--cc=vbabka@suse.cz \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).