On Wed, May 9, 2012 at 11:10 AM, Nick Piggin <npiggin@xxxxxxxxx> wrote: > On 6 May 2012 01:29, KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxx> wrote: >>> So, am I correct to assume that right text to add to the page is as below? >>> >>> Nick, can you clarify what you mean by "quiesced"? >> >> finished? > > Yes exactly. That might be a simpler word. Thanks! Thanks. But see below. I realize the text is still ambiguous. >>> [[ >>> 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). >>> ]] In the above, the status of a MAP_SHARED MAP_ANONYMOUS buffer is unclear. The first paragraph implies that such a buffer is unsafe, while the third paragraph implies that it *is* safe, thus contradicting the first paragraph. Which is correct? Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Author of "The Linux Programming Interface"; http://man7.org/tlpi/ -- 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
