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authorMatthew Wilcox <mawilcox@microsoft.com>2018-04-11 02:36:52 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-11 20:28:39 +0300
commitf6bb2a2c0b81c47282ddb7883f92e65a063c27dd (patch)
tree74eb6dece48af9baee664a3abe1d70b5798f8b0d /mm/migrate.c
parente5a955419642e0842fd26e1ada6ab3328018ca16 (diff)
downloadlinux-f6bb2a2c0b81c47282ddb7883f92e65a063c27dd.tar.xz
xarray: add the xa_lock to the radix_tree_root
This results in no change in structure size on 64-bit machines as it fits in the padding between the gfp_t and the void *. 32-bit machines will grow the structure from 8 to 12 bytes. Almost all radix trees are protected with (at least) a spinlock, so as they are converted from radix trees to xarrays, the data structures will shrink again. Initialising the spinlock requires a name for the benefit of lockdep, so RADIX_TREE_INIT() now needs to know the name of the radix tree it's initialising, and so do IDR_INIT() and IDA_INIT(). Also add the xa_lock() and xa_unlock() family of wrappers to make it easier to use the lock. If we could rely on -fplan9-extensions in the compiler, we could avoid all of this syntactic sugar, but that wasn't added until gcc 4.6. Link: http://lkml.kernel.org/r/20180313132639.17387-8-willy@infradead.org Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> Cc: Darrick J. Wong <darrick.wong@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/migrate.c')
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