On Tue, Dec 10, 2013 at 1:06 AM, Xishi Qiu <qiuxishi@xxxxxxxxxx> wrote: > In the following case, e820_all_mapped() will return 1. > A < start < B-1 and B < end < C, it means <start, end> spans two regions. > <start, end>: [start - end] > e820 addr: ...[A - B-1][B - C]... should be [start, end) right? and [A, B),[B, C) > > Signed-off-by: Xishi Qiu <qiuxishi@xxxxxxxxxx> > --- > arch/x86/kernel/e820.c | 15 +++------------ > 1 files changed, 3 insertions(+), 12 deletions(-) > > diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c > index 174da5f..31ecab2 100644 > --- a/arch/x86/kernel/e820.c > +++ b/arch/x86/kernel/e820.c > @@ -85,20 +85,11 @@ int __init e820_all_mapped(u64 start, u64 end, unsigned type) > > if (type && ei->type != type) > continue; > - /* is the region (part) in overlap with the current region ?*/ > + /* is the region (part) in overlap with the current region ? */ > if (ei->addr >= end || ei->addr + ei->size <= start) > continue; > - > - /* if the region is at the beginning of <start,end> we move > - * start to the end of the region since it's ok until there > - */ > - if (ei->addr <= start) > - start = ei->addr + ei->size; so in your case new start will be B ? next run will be C > - /* > - * if start is now at or beyond end, we're done, full > - * coverage > - */ > - if (start >= end) > + /* is the region full coverage of <start, end> ? */ > + if (ei->addr <= start && ei->addr + ei->size >= end) > return 1; > } > return 0; also e820 should be sanitized already to have [A,C). or you are talking about [A,B), [B+1, C) first run start will be B, and next run with [B+1, ...), that will be skipped... will not return 1. so old code should be ok. Thanks Yinghai -- 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>