From: Miles Chen <miles.chen@mediatek.com>
To: Andrew Morton <akpm@linux-foundation.org>,
Mike Rapoport <rppt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
David Hildenbrand <david@redhat.com>
Cc: <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
<linux-mediatek@lists.infradead.org>, <wsd_upstream@mediatek.com>,
Miles Chen <miles.chen@mediatek.com>
Subject: [PATCH v3] mm/sparse: clarify pgdat_to_phys
Date: Fri, 23 Jul 2021 20:33:42 +0800 [thread overview]
Message-ID: <20210723123342.26406-1-miles.chen@mediatek.com> (raw)
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
--
2.18.0
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next reply other threads:[~2021-07-23 12:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-23 12:33 Miles Chen [this message]
2021-07-23 12:54 ` [PATCH v3] mm/sparse: clarify pgdat_to_phys David Hildenbrand
2021-07-24 7:47 ` Mike Rapoport
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