[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH] xen/page_alloc: Simplify domain_adjust_tot_pages
Open question to whoever reviews this... On Mon Feb 24, 2025 at 1:27 PM GMT, Alejandro Vallejo wrote: > spin_lock(&heap_lock); > - /* adjust domain outstanding pages; may not go negative */ > - dom_before = d->outstanding_pages; > - dom_after = dom_before - pages; > - BUG_ON(dom_before < 0); > - dom_claimed = dom_after < 0 ? 0 : dom_after; > - d->outstanding_pages = dom_claimed; > - /* flag accounting bug if system outstanding_claims would go negative */ > - sys_before = outstanding_claims; > - sys_after = sys_before - (dom_before - dom_claimed); > - BUG_ON(sys_after < 0); > - outstanding_claims = sys_after; > + BUG_ON(outstanding_claims < d->outstanding_pages); > + if ( pages > 0 && d->outstanding_pages < pages ) > + { > + /* `pages` exceeds the domain's outstanding count. Zero it out. */ > + outstanding_claims -= d->outstanding_pages; > + d->outstanding_pages = 0; While this matches the previous behaviour, do we _really_ want it? It's weird, quirky, and it hard to extend to NUMA-aware claims (which is something in midway through). Wouldn't it make sense to fail the allocation (earlier) if the claim has run out? Do we even expect this to ever happen this late in the allocation call chain? > + } else { > + outstanding_claims -= pages; > + d->outstanding_pages -= pages; > + } > spin_unlock(&heap_lock); > > out: Cheers, Alejandro
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