Re: [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()

[David Rientjes]

On Wed, 21 Sep 2016, zijun_hu wrote:

> From: zijun_hu <zijun_hu@xxxxxxx>
> 
> correct a few logic error for __insert_vmap_area() since the else
> if condition is always true and meaningless
> 
> in order to fix this issue, if vmap_area inserted is lower than one
> on rbtree then walk around left branch; if higher then right branch
> otherwise intersects with the other then BUG_ON() is triggered
> 

Under normal operation, you're right that the "else if" conditional should 
always succeed: we don't want to BUG() unless there's a bug.  The original 
code can catch instances when va->va_start == tmp_va->va_end where we 
should BUG().  Your code silently ignores it.