Messages in this thread | | | Date | Tue, 10 Dec 2013 13:06:53 -0800 | Subject | Re: [PATCH] mm,x86: fix span coverage in e820_all_mapped() | From | Yinghai Lu <> |
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On Tue, Dec 10, 2013 at 1:06 AM, Xishi Qiu <qiuxishi@huawei.com> 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@huawei.com> > --- > 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
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