>> >> >> In order to fully utilize the memory chunk allocated from bootmem >> >> >> allocator, it'd better to assure memory sector descriptor won't run >> >> >> across the boundary (PAGE_SIZE). >> > >> >OK, I misread this part of the changelog changelog. >> > >> >> I should have clarified that more clear :-) >> >> >> > >> >> >Why? The memory is continuous, right? >> >> >> >> Yes, the memory is conginous and the capacity of specific entry >> >> in mem_section[NR_SECTION_ROOTS] has been defined as follows: >> >> >> >> >> >> #define SECTIONS_PER_ROOT (PAGE_SIZE / sizeof (struct mem_section)) >> >> >> >> Also, the memory is prone to be allocated from bootmem by function >> >> alloc_bootmem_node(), which has PAGE_SIZE alignment. So I think it's >> >> reasonable to introduce the extra check here from my personal view :-) >> > >> >No it is not necessary because we will never cross the page boundary >> >because (SECTIONS_PER_ROOT uses an int division) >> >> Current situation is that we don't cross the page foundary, but somebody >> else might change the data struct (struct mem_section) in future. > >No, this is safe even if the structure size changes (unless it is bigger >than PAGE_SIZE). Yeah, but it can't fully utilize the allocated memory chunk if the size of the struct isn't aligned well. Let me drop it in next revision :-) Thanks, Gavin >-- >Michal Hocko >SUSE Labs >SUSE LINUX s.r.o. >Lihovarska 1060/12 >190 00 Praha 9 >Czech Republic > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>