| Message ID | 20180817042501.15538-1-rashmica.g@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 3f7daf3d7582dc6628ac40a9045dd1bbd80c5f35 |
| Headers | show |
| Series | powerpc/memtrace: Remove memory in chunks | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | next/apply_patch Successfully applied |
| snowpatch_ozlabs/checkpatch | warning | Test checkpatch on branch next |
| snowpatch_ozlabs/build-ppc64le | success | Test build-ppc64le on branch next |
| snowpatch_ozlabs/build-ppc64be | success | Test build-ppc64be on branch next |
| snowpatch_ozlabs/build-ppc64e | success | Test build-ppc64e on branch next |
| snowpatch_ozlabs/build-ppc32 | success | Test build-ppc32 on branch next |
On Fri, 2018-08-17 at 04:25:01 UTC, Rashmica Gupta wrote: > When hot-removing memory release_mem_region_adjustable() splits iomem > resources if they are not the exact size of the memory being > hot-deleted. Adding this memory back to the kernel adds a new resource. > > Eg a node has memory 0x0 - 0xfffffffff. Hot-removing 1GB from > 0xf40000000 results in the single resource 0x0-0xfffffffff being split > into two resources: 0x0-0xf3fffffff and 0xf80000000-0xfffffffff. > > When we hot-add the memory back we now have three resources: > 0x0-0xf3fffffff, 0xf40000000-0xf7fffffff, and 0xf80000000-0xfffffffff. > > This is an issue if we try to remove some memory that overlaps > resources. Eg when trying to remove 2GB at address 0xf40000000, > release_mem_region_adjustable() fails as it expects the chunk of memory > to be within the boundaries of a single resource. We then get the > warning: "Unable to release resource" and attempting to use memtrace > again gives us this error: "bash: echo: write error: Resource > temporarily unavailable" > > This patch makes memtrace remove memory in chunks that are always the > same size from an address that is always equal to end_of_memory - > n*size, for some n. So hotremoving and hotadding memory of different > sizes will now not attempt to remove memory that spans multiple > resources. > > Signed-off-by: Rashmica Gupta <rashmica.g@gmail.com> Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/3f7daf3d7582dc6628ac40a9045dd1 cheers
diff --git a/arch/powerpc/platforms/powernv/memtrace.c b/arch/powerpc/platforms/powernv/memtrace.c index 51fe0862dcab..c5749f898652 100644 --- a/arch/powerpc/platforms/powernv/memtrace.c +++ b/arch/powerpc/platforms/powernv/memtrace.c @@ -119,17 +119,15 @@ static bool memtrace_offline_pages(u32 nid, u64 start_pfn, u64 nr_pages) walk_memory_range(start_pfn, end_pfn, (void *)MEM_OFFLINE, change_memblock_state); - lock_device_hotplug(); - remove_memory(nid, start_pfn << PAGE_SHIFT, nr_pages << PAGE_SHIFT); - unlock_device_hotplug(); return true; } static u64 memtrace_alloc_node(u32 nid, u64 size) { - u64 start_pfn, end_pfn, nr_pages; + u64 start_pfn, end_pfn, nr_pages, pfn; u64 base_pfn; + u64 bytes = memory_block_size_bytes(); if (!node_spanned_pages(nid)) return 0; @@ -142,8 +140,20 @@ static u64 memtrace_alloc_node(u32 nid, u64 size) end_pfn = round_down(end_pfn - nr_pages, nr_pages); for (base_pfn = end_pfn; base_pfn > start_pfn; base_pfn -= nr_pages) { - if (memtrace_offline_pages(nid, base_pfn, nr_pages) == true) + if (memtrace_offline_pages(nid, base_pfn, nr_pages) == true) { + /* Remove memory in memory block size chunks so that + * iomem resources are always split to the same size + * and we never try to remove memory that spans two + * iomem resources. + */ + lock_device_hotplug(); + end_pfn = base_pfn + nr_pages; + for (pfn = base_pfn; pfn < end_pfn; pfn += bytes>> PAGE_SHIFT) { + remove_memory(nid, pfn << PAGE_SHIFT, bytes); + } + unlock_device_hotplug(); return base_pfn << PAGE_SHIFT; + } } return 0;
When hot-removing memory release_mem_region_adjustable() splits iomem resources if they are not the exact size of the memory being hot-deleted. Adding this memory back to the kernel adds a new resource. Eg a node has memory 0x0 - 0xfffffffff. Hot-removing 1GB from 0xf40000000 results in the single resource 0x0-0xfffffffff being split into two resources: 0x0-0xf3fffffff and 0xf80000000-0xfffffffff. When we hot-add the memory back we now have three resources: 0x0-0xf3fffffff, 0xf40000000-0xf7fffffff, and 0xf80000000-0xfffffffff. This is an issue if we try to remove some memory that overlaps resources. Eg when trying to remove 2GB at address 0xf40000000, release_mem_region_adjustable() fails as it expects the chunk of memory to be within the boundaries of a single resource. We then get the warning: "Unable to release resource" and attempting to use memtrace again gives us this error: "bash: echo: write error: Resource temporarily unavailable" This patch makes memtrace remove memory in chunks that are always the same size from an address that is always equal to end_of_memory - n*size, for some n. So hotremoving and hotadding memory of different sizes will now not attempt to remove memory that spans multiple resources. Signed-off-by: Rashmica Gupta <rashmica.g@gmail.com> --- To replicate the above issue hot-remove and hot-add memory of different sizes a bunch of times. This does it for me on POWER8 and POWER9: for i in `seq 1 10`; do echo $(( $i * 268435456)) > /sys/kernel/debug/powerpc/memtrace/enable echo '.' done arch/powerpc/platforms/powernv/memtrace.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-)