From: David Hildenbrand <david@redhat.com>
To: Miles Chen <miles.chen@mediatek.com>,
Andrew Morton <akpm@linux-foundation.org>,
Mike Rapoport <rppt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-mediatek@lists.infradead.org, wsd_upstream@mediatek.com
Subject: Re: [PATCH v3] mm/sparse: clarify pgdat_to_phys
Date: Fri, 23 Jul 2021 14:54:29 +0200 [thread overview]
Message-ID: <571dcb1d-1f3a-0633-17e1-1ca9856bee5e@redhat.com> (raw)
In-Reply-To: <20210723123342.26406-1-miles.chen@mediatek.com>
On 23.07.21 14:33, Miles Chen wrote:
> Clarify pgdat_to_phys() by testing if
> pgdat == &contig_page_data when CONFIG_NUMA=n.
>
> We only expect contig_page_data in such case, so we
> use &contig_page_data directly instead of pgdat.
>
> No functional change intended when CONFIG_BUG_VM=n.
>
> Comment from Mark [1]:
> "
> ... and I reckon it'd be clearer and more robust to define
> pgdat_to_phys() in the same ifdefs as contig_page_data so
> that these, stay in-sync. e.g. have:
>
> | #ifdef CONFIG_NUMA
> | #define pgdat_to_phys(x) virt_to_phys(x)
> | #else /* CONFIG_NUMA */
> |
> | extern struct pglist_data contig_page_data;
> | ...
> | #define pgdat_to_phys(x) __pa_symbol(&contig_page_data)
> |
> | #endif /* CONIFIG_NUMA */
> "
>
> [1] https://lore.kernel.org/linux-arm-kernel/20210615131902.GB47121@C02TD0UTHF1T.local/
>
> Cc: Mike Rapoport <rppt@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: David Hildenbrand <david@redhat.com>
> Signed-off-by: Miles Chen <miles.chen@mediatek.com>
>
> --
>
> Change since v1:
> Thanks for Mike's comment, check if pgdat == &contig_page_data,
> so it is clearer that we only expect contig_page_data when
> CONFIG_NUMA=n.
>
> Change since v2:
> use VM_BUG_ON() to avoid runtime checking when CONFIG_BUG_VM=n
> ---
> mm/sparse.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/sparse.c b/mm/sparse.c
> index 6326cdf36c4f..d13d831f88a5 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -348,7 +348,8 @@ size_t mem_section_usage_size(void)
> static inline phys_addr_t pgdat_to_phys(struct pglist_data *pgdat)
> {
> #ifndef CONFIG_NUMA
> - return __pa_symbol(pgdat);
> + VM_BUG_ON(pgdat != &contig_page_data);
> + return __pa_symbol(&contig_page_data);
> #else
> return __pa(pgdat);
> #endif
>
Reviewed-by: David Hildenbrand <david@redhat.com>
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2021-07-23 12:54 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-23 12:33 [PATCH v3] mm/sparse: clarify pgdat_to_phys Miles Chen
2021-07-23 12:54 ` David Hildenbrand [this message]
2021-07-24 7:47 ` Mike Rapoport
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=571dcb1d-1f3a-0633-17e1-1ca9856bee5e@redhat.com \
--to=david@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mediatek@lists.infradead.org \
--cc=linux-mm@kvack.org \
--cc=mark.rutland@arm.com \
--cc=miles.chen@mediatek.com \
--cc=rppt@kernel.org \
--cc=wsd_upstream@mediatek.com \
/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).