Kukjin, Could you test below patch? I don't have any sparsemem system. Sorry. -- CUT DOWN HERE -- Kukjin reported oops happen while he change min_free_kbytes http://www.spinics.net/lists/arm-kernel/msg92894.html It happen by memory map on sparsemem. The system has a memory map following as. section 0 section 1 section 2 0x20000000-0x25000000, 0x40000000-0x50000000, 0x50000000-0x58000000 SECTION_SIZE_BITS 28(256M) It means section 0 is an incompletely filled section. Nontheless, current pfn_valid of sparsemem checks pfn loosely. It checks only mem_section's validation. So in above case, pfn on 0x25000000 can pass pfn_valid's validation check. It's not what we want. The Following patch adds check valid pfn range check on pfn_valid of sparsemem. Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx> Reported-by: Kukjin Kim <kgene.kim@xxxxxxxxxxx> P.S) It is just RFC. If we agree with this, I will make the patch on mmotm. -- diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index b4d109e..6c2147a 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -979,6 +979,8 @@ struct mem_section { struct page_cgroup *page_cgroup; unsigned long pad; #endif + unsigned long start_pfn; + unsigned long end_pfn; }; #ifdef CONFIG_SPARSEMEM_EXTREME @@ -1039,6 +1041,12 @@ static inline int valid_section(struct mem_section *section) return (section && (section->section_mem_map & SECTION_HAS_MEM_MAP)); } +static inline int valid_section_pfn(struct mem_section *section, unsigned long pfn) +{ + return ((section && (section->section_mem_map & SECTION_HAS_MEM_MAP)) && + (section->start_pfn <= pfn && pfn < section->end_pfn)); +} + static inline int valid_section_nr(unsigned long nr) { return valid_section(__nr_to_section(nr)); @@ -1053,7 +1061,7 @@ static inline int pfn_valid(unsigned long pfn) { if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) return 0; - return valid_section(__nr_to_section(pfn_to_section_nr(pfn))); + return valid_section_pfn(__nr_to_section(pfn_to_section_nr(pfn)), pfn); } diff --git a/mm/sparse.c b/mm/sparse.c index 95ac219..bde9090 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -195,6 +195,8 @@ void __init memory_present(int nid, unsigned long start, unsigned long end) if (!ms->section_mem_map) ms->section_mem_map = sparse_encode_early_nid(nid) | SECTION_MARKED_PRESENT; + ms->start_pfn = start; + ms->end_pfn = end; } } -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>