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authorDan Williams <dan.j.williams@intel.com>2017-09-06 16:24:13 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-09-06 17:27:29 -0700
commitab1b597ee0e4208a1db227bb7b2c9512c8234b48 (patch)
tree57d44937a91ae2e91e4c8bf741e6e4d326933064 /mm
parentc568da282bbc8f09c4b49201177fa259fe184c47 (diff)
mm, devm_memremap_pages: use multi-order radix for ZONE_DEVICE lookups
devm_memremap_pages() records mapped ranges in pgmap_radix with an entry per section's worth of memory (128MB). The key for each of those entries is a section number. This leads to false positives when devm_memremap_pages() is passed a section-unaligned range as lookups in the misalignment fail to return NULL. We can close this hole by using the pfn as the key for entries in the tree. The number of entries required to describe a remapped range is reduced by leveraging multi-order entries. In practice this approach usually yields just one entry in the tree if the size and starting address are of the same power-of-2 alignment. Previously we always needed nr_entries = mapping_size / 128MB. Link: https://lists.01.org/pipermail/linux-nvdimm/2016-August/006666.html Link: http://lkml.kernel.org/r/150215410565.39310.13767886055248249438.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com> Reported-by: Toshi Kani <toshi.kani@hpe.com> Cc: Matthew Wilcox <mawilcox@microsoft.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/Kconfig1
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/Kconfig b/mm/Kconfig
index 48b1af447fa7..0ded10a22639 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -678,6 +678,7 @@ config ZONE_DEVICE
depends on MEMORY_HOTREMOVE
depends on SPARSEMEM_VMEMMAP
depends on ARCH_HAS_ZONE_DEVICE
+ select RADIX_TREE_MULTIORDER
help
Device memory hotplug support allows for establishing pmem,