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Date: Fri, 20 Feb 2009 12:08:09 +0900 From: Tejun Heo <tj@...nel.org> To: Rusty Russell <rusty@...tcorp.com.au> CC: Ingo Molnar <mingo@...e.hu>, tglx@...utronix.de, x86@...nel.org, linux-kernel@...r.kernel.org, hpa@...or.com, jeremy@...p.org, cpw@....com Subject: Re: [PATCHSET x86/core/percpu] implement dynamic percpu allocator Rusty Russell wrote: >>>> Rusty, if the fixes are fine with you i can put those two >>>> commits into tip/core/urgent straight away, the full string of >>>> 10 commits into tip/core/percpu and thus we'd avoid duplicate >>>> (or even conflicting) commits. >>> No, the second one is not .29 material; it's a nice, but >>> theoretical, fix. >> Can it never trigger? > > Actually, checked again. It's not even necessary AFAICT (tho a comment > would be nice): > > for (i = 0; i < pcpu_num_used; ptr += block_size(pcpu_size[i]), i++) { > /* Extra for alignment requirement. */ > extra = ALIGN((unsigned long)ptr, align) - (unsigned long)ptr; > BUG_ON(i == 0 && extra != 0); > > if (pcpu_size[i] < 0 || pcpu_size[i] < extra + size) > continue; > > /* Transfer extra to previous block. */ > if (pcpu_size[i-1] < 0) > pcpu_size[i-1] -= extra; > else > pcpu_size[i-1] += extra; > > pcpu_size[0] is *always* negative: it's marked allocated at initialization > (it's the static per-cpu allocations). > > Sorry I didn't examine more closely, Ah... okay. Right. I took the code and used it in the chunk area allocator where 0 isn't guaranteed to be occupied and saw the problem triggering and then assumed the modalloc allocator shared the same problem. So, unnecessary fix but I think it really needs some explanation. What to do about #tj-percpu? Ingo, do you want me to rebase tree sans the second one? Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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