[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v1 1/9] mm: Separate free page chunk merging into its own routine
On 03/28/2017 03:44 PM, Wei Liu wrote: > On Tue, Mar 28, 2017 at 03:41:10PM -0400, Boris Ostrovsky wrote: >> On 03/28/2017 03:20 PM, Wei Liu wrote: >>> On Fri, Mar 24, 2017 at 01:04:56PM -0400, Boris Ostrovsky wrote: >>>> This is needed for subsequent changes to memory scrubbing. No >>>> logic change, only code re-factoring. >>> Actually there is a slight change in logic: pg and order could be >>> updated in the original merge code. With this patch you still pass the >>> original pg to reserve_offlined_page if tainted is true. I don't think >>> this matters in terms of correctness, but it is worth pointing out. >> Actually, for pg it does matter since reserve_offlined_page() is passed >> buddy head. So I should make merge_chunks() return new head. >> > OK. I think the downside is reserve_offlined_page doesn't merge as many > pages as it should have, so it is still correct, just the result is > suboptimal, but I could be wrong -- it's a bit late here. :-) You are wrong that my patch was right. ;-) I was passing old head which, if it was merged back in merge_chunks(), would have lost its PGC_need_scrub bit. And so when reserve_offlined_page() tries to re-merge buddy's pieces all need_scrub info would be lost. Again, this would have been OK with previous version of the series where every page in the buddy was marked with PGC_need_scrub. But this is no longer the case. -boris > > I think returning the updated pg is probably best. > > Wei. > >> ('order' is not used after merge_chunks(), so that's OK). >> >> -boris _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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