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Message-ID: <4643364.iqi5kenykK@vostro.rjw.lan> Date: Sun, 04 Aug 2013 16:12:27 +0200 From: "Rafael J. Wysocki" <rjw@...k.pl> To: Toshi Kani <toshi.kani@...com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>, rafael.j.wysocki@...el.com, vasilis.liaskovitis@...fitbricks.com, linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org, tangchen@...fujitsu.com, wency@...fujitsu.com Subject: Re: Cannot hot remove a memory device On Saturday, August 03, 2013 06:37:26 PM Toshi Kani wrote: > On Sat, 2013-08-03 at 03:01 +0200, Rafael J. Wysocki wrote: > > On Friday, August 02, 2013 06:04:40 PM Toshi Kani wrote: > > > On Sat, 2013-08-03 at 01:43 +0200, Rafael J. Wysocki wrote: > > > > On Friday, August 02, 2013 03:46:15 PM Toshi Kani wrote: > > > > > On Thu, 2013-08-01 at 23:43 +0200, Rafael J. Wysocki wrote: > > > > > > Hi, > > > > > > > > > > > > Thanks for your report. > > > > > > > > > > > > On Thursday, August 01, 2013 05:37:21 PM Yasuaki Ishimatsu wrote: > > > > > > > By following commit, I cannot hot remove a memory device. > > > > > > > > > > > > > > ACPI / memhotplug: Bind removable memory blocks to ACPI device nodes > > > > > > > commit e2ff39400d81233374e780b133496a2296643d7d > > > > > > > > > > > > > > Details are follows: > > > > > > > When I add a memory device, acpi_memory_enable_device() always fails > > > > > > > as follows: > > > > > > > > > > > > > > ... > > > > > > > [ 1271.114116] [ffffea121c400000-ffffea121c7fffff] PMD -> [ffff880813c00000-ffff880813ffffff] on node 3 > > > > > > > [ 1271.128682] [ffffea121c800000-ffffea121cbfffff] PMD -> [ffff880813800000-ffff880813bfffff] on node 3 > > > > > > > [ 1271.143298] [ffffea121cc00000-ffffea121cffffff] PMD -> [ffff880813000000-ffff8808133fffff] on node 3 > > > > > > > [ 1271.157799] [ffffea121d000000-ffffea121d3fffff] PMD -> [ffff880812c00000-ffff880812ffffff] on node 3 > > > > > > > [ 1271.172341] [ffffea121d400000-ffffea121d7fffff] PMD -> [ffff880812800000-ffff880812bfffff] on node 3 > > > > > > > [ 1271.186872] [ffffea121d800000-ffffea121dbfffff] PMD -> [ffff880812400000-ffff8808127fffff] on node 3 > > > > > > > [ 1271.201481] [ffffea121dc00000-ffffea121dffffff] PMD -> [ffff880812000000-ffff8808123fffff] on node 3 > > > > > > > [ 1271.216041] [ffffea121e000000-ffffea121e3fffff] PMD -> [ffff880811c00000-ffff880811ffffff] on node 3 > > > > > > > [ 1271.230623] [ffffea121e400000-ffffea121e7fffff] PMD -> [ffff880811800000-ffff880811bfffff] on node 3 > > > > > > > [ 1271.245148] [ffffea121e800000-ffffea121ebfffff] PMD -> [ffff880811400000-ffff8808117fffff] on node 3 > > > > > > > [ 1271.259683] [ffffea121ec00000-ffffea121effffff] PMD -> [ffff880811000000-ffff8808113fffff] on node 3 > > > > > > > [ 1271.274194] [ffffea121f000000-ffffea121f3fffff] PMD -> [ffff880810c00000-ffff880810ffffff] on node 3 > > > > > > > [ 1271.288764] [ffffea121f400000-ffffea121f7fffff] PMD -> [ffff880810800000-ffff880810bfffff] on node 3 > > > > > > > > > > It appears that each memory object only has 64MB of memory. This is > > > > > less than the memory block size, which is 128MB. This means that a > > > > > single memory block associates with two ACPI memory device objects. > > > > > > > > That'd be bad. > > > > > > > > How did that work before if that indeed is the case? > > > > > > Well, it looks to me that it has never worked before... > > > > > > > > > > ... > > > > > > > [ 1271.325841] acpi PNP0C80:03: acpi_memory_enable_device() error > > > > > > > > > > > > Well, the only new way acpi_memory_enable_device() can fail after that commit > > > > > > is a failure in acpi_bind_memory_blocks(). > > > > > > > > > > Agreed. > > > > > > > > > > > This means that either handle is NULL, which I think we can exclude, because > > > > > > acpi_memory_enable_device() wouldn't be called at all if that were the case, or > > > > > > there's a more subtle error in acpi_bind_one(). > > > > > > > > > > > > One that comes to mind is that we may be calling acpi_bind_one() twice for the > > > > > > same memory region, in which it will trigger -EINVAL from the sanity check in > > > > > > there. > > > > > > > > > > I think it fails with -EINVAL at the place with dev_warn(dev, "ACPI > > > > > handle is already set\n"). When two ACPI memory objects associate with > > > > > a same memory block, the bind procedure of the 2nd ACPI memory object > > > > > sees that ACPI_HANDLE(dev) is already set to the 1st ACPI memory object. > > > > > > > > That sound's plausible, but I wonder how we can fix that? > > > > > > > > There's no way for a single physical device to have two different ACPI > > > > "companions". It looks like the memory blocks should be 64 M each in that > > > > case. Or we need to create two child devices for each memory block and > > > > associate each of them with an ACPI object. That would lead to complications > > > > in the user space interface, though. > > > > > > Right. Even bigger issue is that I do not think __add_pages() and > > > __remove_pages() can add / delete a memory chunk that is less than > > > 128MB. 128MB is the granularity of them. So, we may just have to fail > > > this case gracefully. > > > > Sigh. > > > > BTW, why do you think they are 64 M each (it's late and I'm obviously tired)? > > Oops! Sorry, I had confused the above messages with the one in > init_memory_mapping(), which shows a memory range being added, i.e. the > size of an ACPI memory device object. But the above messages actually > came from vmemmap_populate_hugepages(), which was called during boot-up. > So, these messages have nothing to do with ACPI memory device objects. > And even worse, I do not seem to be able to count a number of zeros... > In the above messages, each memory range is 4MB (0x400000), not 64MB > (0x4000000)... My bad. :-( Well, no problem. :-) > So, while we may still need to do something for the less-than-128MB > issue, Yasuaki may be hitting a different one. Let's wait for Yasuaki > to give us more info. My somewhat educated guess is that ACPI_MAX_PHYSICAL_NODE is too low for that particular system, but that only is a guess. Thanks, Rafael -- 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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