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Re: [PATCH] aio: fix a use after free (and fix freeze protection of aio writes)

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On Mon, Oct 17, 2016 at 02:19:47PM -0400, Jeff Moyer wrote:
> This ends up being a call to __sb_end_write:
> 
> void __sb_end_write(struct super_block *sb, int level)
> {
>         percpu_up_read(sb->s_writers.rw_sem + level-1);
> }
> 
> Nothing guarantees that submission and completion happen on the same
> CPU.  Is this safe?

Good point.  From my reading of the percpu_rwsem implementation it
is not safe to release it from a different CPU.  Which makes me
wonder how we can protect aio writes properly here..

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[PATCH] aio: fix a use after free (and fix freeze protection of aio writes) Christoph Hellwig <hch@lst.de> - 2016-10-16 08:00 +0200
  Re: [PATCH] aio: fix a use after free (and fix freeze protection of aio writes) Jeff Moyer <jmoyer@redhat.com> - 2016-10-17 20:30 +0200
    Re: [PATCH] aio: fix a use after free (and fix freeze protection         of aio writes) Christoph Hellwig <hch@lst.de> - 2016-10-17 21:00 +0200
      Re: [PATCH] aio: fix a use after free (and fix freeze protection of aio writes) Jeff Moyer <jmoyer@redhat.com> - 2016-10-17 21:50 +0200
        Re: [PATCH] aio: fix a use after free (and fix freeze protection of  aio writes) Peter Zijlstra <peterz@infradead.org> - 2016-10-17 22:00 +0200
          Re: [PATCH] aio: fix a use after free (and fix freeze protection         of aio writes) Christoph Hellwig <hch@lst.de> - 2016-10-17 22:10 +0200
          Re: [PATCH] aio: fix a use after free (and fix freeze protection of aio writes) Jeff Moyer <jmoyer@redhat.com> - 2016-10-17 22:10 +0200
      Re: [PATCH] aio: fix a use after free (and fix freeze protection of  aio writes) Peter Zijlstra <peterz@infradead.org> - 2016-10-17 22:00 +0200
  Re: [PATCH] aio: fix a use after free (and fix freeze protection of aio writes) Jeff Moyer <jmoyer@redhat.com> - 2016-10-17 22:10 +0200
  Re: [PATCH] aio: fix a use after free (and fix freeze protection         of aio writes) Christoph Hellwig <hch@lst.de> - 2016-10-24 08:40 +0200

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