Re: [PATCH 13/12] ksm: fix munlock during exit_mmap deadlock

From: Izik Eidus
Date: Thu Aug 27 2009 - 15:28:48 EST


Hugh Dickins wrote:

It may be that MADV_UNMERGEABLE isn't really needed (I think I even
admitted once that probably nobody would use it other than we testing
it). Yet I hesitate to rip it out: somehow it still seems right to
have it in there. Why did you have unregistering in the /dev/ksm KSM?

It was more to give possiblaty to applications save cpu cycles of ksmd so it wont continue to scan memory regions that don`t need ksm anymore,
As you said if someone will ever use it?, have no idea...

I didn't seem idiotic to me, but I hadn't realized the ksmd timelapse
uncertainty Andrea points out. Well, I'm not keen to change the way
it's working at present, but I do think you're right to question all
these aspects of unmerging.

Yes lets keep it like that, UNMERGEABLE sound anyway like something that going to break the pages..., we can always add later STOPMERGE as a call that tell ksm to stop merge the pages but not break the shared pages...

Hugh

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