[4/4] SLAB: Fix node add timer race in cache_reap
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From: Christoph Lameter on 26 Feb 2010 12:30 On Fri, 26 Feb 2010, Andi Kleen wrote: > > > Memory hotplug with node add never quite worked on x86 before, > > > for various reasons not related to slab. > > > > Ok but why did things break in such a big way? > > 1) numa memory hotadd never worked Well Kamesan indicated that this worked if a cpu became online. > 2) the rest just bitrotted because nobody tested it. Yep. David: Can you revise the relevant portions of the patchset and repost it? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Andi Kleen on 26 Feb 2010 12:40 On Fri, Feb 26, 2010 at 11:24:50AM -0600, Christoph Lameter wrote: > On Fri, 26 Feb 2010, Andi Kleen wrote: > > > > > Memory hotplug with node add never quite worked on x86 before, > > > > for various reasons not related to slab. > > > > > > Ok but why did things break in such a big way? > > > > 1) numa memory hotadd never worked > > Well Kamesan indicated that this worked if a cpu became online. I mean in the general case. There were tons of problems all over. -Andi -- ak(a)linux.intel.com -- Speaking for myself only. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: David Rientjes on 26 Feb 2010 19:10 On Fri, 26 Feb 2010, Christoph Lameter wrote: > > 1) numa memory hotadd never worked > > Well Kamesan indicated that this worked if a cpu became online. > That may be true, but it doesn't address hotpluggable ACPI_SRAT_MEM_HOT_PLUGGABLE entries for CONFIG_MEMORY_HOTPLUG_SPARSE where no cpus are being onlined or writing to /sys/devices/system/memory/probe for CONFIG_ARCH_MEMORY_PROBE. > > 2) the rest just bitrotted because nobody tested it. > > Yep. David: Can you revise the relevant portions of the patchset and > repost it? > Ok. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: KAMEZAWA Hiroyuki on 28 Feb 2010 21:10 On Fri, 26 Feb 2010 18:31:15 +0100 Andi Kleen <andi(a)firstfloor.org> wrote: > On Fri, Feb 26, 2010 at 11:24:50AM -0600, Christoph Lameter wrote: > > On Fri, 26 Feb 2010, Andi Kleen wrote: > > > > > > > Memory hotplug with node add never quite worked on x86 before, > > > > > for various reasons not related to slab. > > > > > > > > Ok but why did things break in such a big way? > > > > > > 1) numa memory hotadd never worked > > > > Well Kamesan indicated that this worked if a cpu became online. > > I mean in the general case. There were tons of problems all over. > Then, it's cpu hotplug matter, not memory hotplug. cpu hotplug callback should prepaare l3 = searchp->nodelists[node]; BUG_ON(!l3); before onlined. Rather than taking care of races. Thanks, -Kame -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: David Rientjes on 1 Mar 2010 05:30
On Mon, 1 Mar 2010, KAMEZAWA Hiroyuki wrote: > > > Well Kamesan indicated that this worked if a cpu became online. > > > > I mean in the general case. There were tons of problems all over. > > > Then, it's cpu hotplug matter, not memory hotplug. > cpu hotplug callback should prepaare > > > l3 = searchp->nodelists[node]; > BUG_ON(!l3); > > before onlined. Rather than taking care of races. > I can only speak for x86 and not the abundance of memory hotplug support that exists for powerpc, but cpu hotplug doesn't do _anything_ when a memory region that has a corresponding ACPI_SRAT_MEM_HOT_PLUGGABLE entry in the SRAT is hotadded and requires a new nodeid. That can be triggered via the acpi layer with plug and play or explicitly from the command line via CONFIG_ARCH_MEMORY_PROBE. Relying on cpu hotplug to set up nodelists in such a circumstance simply won't work. You need memory hotplug support such as in my patch. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |