On Fri 20-01-23 09:50:01, Suren Baghdasaryan wrote: > On Fri, Jan 20, 2023 at 9:32 AM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: [...] > > The page fault handler (or whatever other reader -- ptrace, proc, etc) > > should have a refcount on the mm_struct, so we can't be in this path > > trying to free VMAs. Right? > > Hmm. That sounds right. I checked process_mrelease() as well, which > operated on mm with only mmgrab()+mmap_read_lock() but it only unmaps > VMAs without freeing them, so we are still good. Michal, do you agree > this is ok? Don't we need RCU procetions for the vma life time assurance? Jann has already shown how rwsem is not safe wrt to unlock and free without RCU. -- Michal Hocko SUSE Labs
