Messages in this thread | | | Subject | Re: [PATCH v4] mm: per-thread vma caching | From | Davidlohr Bueso <> | Date | Sat, 08 Mar 2014 19:22:25 -0800 |
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On Sat, 2014-03-08 at 12:02 -0800, Linus Torvalds wrote: > On Sat, Mar 8, 2014 at 11:44 AM, Oleg Nesterov <oleg@redhat.com> wrote: > > > > Sure. But another thread or CLONE_VM task can do vmacache_invalidate(), > > hit vmacache_seqnum == 0 and call vmacache_flush_all() to solve the > > problem with potential overflow. > > How? > > Any invalidation is supposed to hold the mm semaphore for writing. And > we should have it for reading.
Yes, invalidations are always with the write lock held. In any case it's a good candidate to use verify_mm_writelocked(), even if it's only under debug environments.
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