On Tue 01-05-12 20:04:15, Hugh Dickins wrote: > On Wed, 2 May 2012, Nick Piggin wrote: > > On 2 May 2012 03:56, Michael Kerrisk (man-pages) <mtk.manpages@xxxxxxxxx> wrote: > > > > > > In the light of all of the comments, can someone revise the man-pages > > > patch that Jan sent? > > > > This does not quite describe the entire situation, but something understandable > > to developers: > > > > O_DIRECT IOs should never be run concurrently with fork(2) system call, > > when the memory buffer is anonymous memory, or comes from mmap(2) > > with MAP_PRIVATE. > > > > Any such IOs, whether submitted with asynchronous IO interface or from > > another thread in the process, should be quiesced before fork(2) is called. > > Failure to do so can result in data corruption and undefined behavior in > > parent and child processes. > > > > This restriction does not apply when the memory buffer for the O_DIRECT > > IOs comes from mmap(2) with MAP_SHARED or from shmat(2). > > Nor does this restriction apply when the memory buffer has been advised > as MADV_DONTFORK with madvise(2), ensuring that it will not be available > to the child after fork(2). Yes, I think with this addition the text is fine. Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
