Messages in this thread | | | Date | Mon, 23 Jan 2023 10:56:32 +0100 | From | Michal Hocko <> | Subject | Re: [PATCH 39/41] kernel/fork: throttle call_rcu() calls in vm_area_free |
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On Fri 20-01-23 09:50:01, Suren Baghdasaryan wrote: > On Fri, Jan 20, 2023 at 9:32 AM Matthew Wilcox <willy@infradead.org> 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
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