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@xxxxxxxxxx> Cc: Mark Rutland <mark.rutland@xxxxxxx> Cc: David Hildenbrand <david@xxxxxxxxxx> Signed-off-by: Miles Chen <miles.chen@xxxxxxxxxxxx> -- 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@xxxxxxxxxx> -- Thanks, David / dhildenb
