On 08/11/2017 04:24 PM, Michal Hocko wrote: > On Fri 11-08-17 16:11:44, Florian Weimer wrote: >> On 08/11/2017 04:06 PM, Michal Hocko wrote: >> >>> I am sorry to look too insisting here (I have still hard time to reconcile >>> myself with the madvise (ab)use) but if we in fact want minherit like >>> interface why don't we simply add minherit and make the code which wants >>> to use that interface easier to port? Is the only reason that hooking >>> into madvise is less code? If yes is that a sufficient reason to justify >>> the (ab)use of madvise? If there is a general consensus on that part I >>> will shut up and won't object anymore. Arguably MADV_DONTFORK would fit >>> into minherit API better as well. >> >> It does, OpenBSD calls it MAP_INHERIT_NONE. >> >> Could you implement MAP_INHERIT_COPY and MAP_INHERIT_SHARE as well? Or >> is changing from MAP_SHARED to MAP_PRIVATE and back impossible? > > I haven't explored those two very much. Their semantic seems rather > awkward, especially map_inherit_share one. I guess MAP_INHERIT_COPY > would be doable. Do we have to support all modes or a missing support > would disqualify the syscall completely? I think it would be a bit awkward if we implemented MAP_INHERIT_ZERO and it would not turn a shared mapping into a private mapping in the child, or would not work on shared mappings at all, or deviate in any way from the OpenBSD implementation. MAP_INHERIT_SHARE for a MAP_PRIVATE mapping which has been modified is a bit bizarre, and I don't know how OpenBSD implements any of this. It could well be that the exact behavior implemented in OpenBSD is a poor fit for the Linux VM implementation. Florian -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
