On Sat, Aug 23, 2014 at 04:43:27PM +0200, Oleg Nesterov wrote: > The ->start_stack check in do_shmat() looks ugly and simply wrong. > > 1. ->start_stack is only valid right after exec(), the application > can switch to another stack and even unmap this area. > > 2. The reason for this check is not clear at all. The application > should know what it does. And why 4 pages? And why in fact it > requires 5 pages? > > 3. This wrongly assumes that the stack can only grown down. > > Personally I think we should simply kill this check, but I did not > dare to do this. So the patch only fixes the 1st problem (mostly to > avoid the usage of mm->start_stack) and ignores VM_GROWSUP. > > Signed-off-by: Oleg Nesterov <[email protected]> Reviewed-by: Cyrill Gorcunov <[email protected]>
I don't understand this check either, the comment above it says nothing but only commits what code is doing not explaining why. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
