| Message ID | 20210706055152.15780-1-miles.chen@mediatek.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] mm/sparse: clarify pgdat_to_phys | expand |
diff --git a/mm/sparse.c b/mm/sparse.c index 6326cdf36c4f..f73ff3c124c5 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -348,10 +348,11 @@ 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); -#else + if (pgdat == &contig_page_data) + return __pa_symbol(&contig_page_data); + pr_warn("Unexpected pglist_data pointer!\n"); +#endif /* !CONFIG_NUMA */ return __pa(pgdat); -#endif } #ifdef CONFIG_MEMORY_HOTREMOVE
Clarify pgdat_to_phys() by testing if pgdat == &contig_page_data when CONFIG_NUMA=n. contig_page_data is only available when CONFIG_NUMA=n so we have to use #ifndef here. No functional change intended. 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 */ " Comment from Mike [2]: " I'm not sure a macro is better than a static inline. Maybe we'd want to warn if pgdat passed to pgtat_to_phys() is not &contig_page_data, e.g something like static inline phys_addr_t pgdat_to_phys(struct pglist_data *pgdat) { if (!IS_ENABLED(CONFIG_NUMA)) { if (pgdat == &contig_page_data) return __pa_symbol(&contig_page_data); else pr_warn("Unexpected pglist_data pointer!\n"); } return __pa(pgdat); } " [1] https://lore.kernel.org/linux-arm-kernel/20210615131902.GB47121@C02TD0UTHF1T.local/ [2] https://lore.kernel.org/patchwork/patch/1452903/#1650759 Cc: Mike Rapoport <rppt@kernel.org> Cc: Mark Rutland <mark.rutland@arm.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. --- mm/sparse.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)