On Thu, Jan 03, 2013 at 06:40:05PM -0600, Simon Jeons wrote: > On Wed, 2012-12-19 at 19:01 -0800, Michel Lespinasse wrote: > > Hi Simon, > > > > On Wed, Dec 19, 2012 at 5:56 PM, Simon Jeons <simon.jeons@xxxxxxxxx> wrote: > > > One question. > > > > > > I found that mainly callsite of expand_stack() is #PF, but it holds > > > mmap_sem each time before call expand_stack(), how can hold a *shared* > > > mmap_sem happen? > > > > the #PF handler calls down_read(&mm->mmap_sem) before calling expand_stack. > > > > I think I'm just confusing you with my terminology; shared lock == > > read lock == several readers might hold it at once (I'd say they share > > it) > > Sorry for my late response. > > Since expand_stack() will modify vma, then why hold a read lock here? To prevent that vma being ripped out. -- 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>