Messages in this thread | | | Date | Mon, 5 Aug 2013 13:00:40 +0900 | From | Yasuaki Ishimatsu <> | Subject | Re: Cannot hot remove a memory device |
| |
(2013/08/04 9:37), 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. :-( > > 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.
acpi_bind_memory_blocks() failed with -ENOSPC.
int acpi_bind_one(struct device *dev, acpi_handle handle) { ... /* allocate physical node id according to physical_node_id_bitmap */ physical_node->node_id = find_first_zero_bit(acpi_dev->physical_node_id_bitmap, ACPI_MAX_PHYSICAL_NODE); if (physical_node->node_id >= ACPI_MAX_PHYSICAL_NODE) { retval = -ENOSPC; => here goto err_free; }
When adding memory device, acpi_bind_memroy_blocks() calls acpi_bind_one() "memory device size / 128MiB" times. So ACPI_MAX_PHYSICAL_NODE need to be set "memory device size / 128MiB" or more. But ACPI_MAX_PHYSICAL_NODE is 32. So acpi_bind_memory_blocks() always failed with -ENOSPC.
I'll test again after increasing ACPI_MAX_PHYSICAL_NODE to enough size.
Thanks, Yasuaki Ishimatsu
> > Thanks, > -Toshi > > > > > > > > >
| |