On Tue, Mar 27, 2018 at 02:38:11PM -0400, Yang Shi wrote: > > Why do we need to hold mmap_sem here and call find_vma, when only > > PR_SET_MM_ENV_END: is consuming it? I guess we can replace it wit the > > new lock and take the mmap_sem only for PR_SET_MM_ENV_END. > > Actually, I didn't think of why. It looks prctl_set_mm() checks if vma does > exist when it tries to set stack_start, argv_* and env_*, btw not only > env_end. > > Cyrill may be able to give us some hint since C/R is the main user of this > API. First and most important it makes code smaller. This prctl call is really rarely used. Of course we can optimize it, but as I said I would prefer to simply deprecate this old interface (and I gonne to do so once time permit).
