Hello all.
Recently I came across high fragmentation of vm_map_ram allocator: vmap_block
has free space, but still new blocks continue to appear. Further investigation
showed that certain mapping/unmapping sequence can exhaust vmalloc space. On
small 32bit systems that's not a big problem, cause purging will be called soon
on a first allocation failure (alloc_vmap_area), but on 64bit machines, e.g.
x86_64 has 45 bits of vmalloc space, that can be a disaster.
Fixing this I also did some tweaks in allocation logic of a new vmap block and
replaced dirty bitmap with min/max dirty range values to make the logic simpler.
I would like to receive comments on the following three patches.
Thanks.
Roman Pen (3):
mm/vmalloc: fix possible exhaustion of vmalloc space caused by
vm_map_ram allocator
mm/vmalloc: occupy newly allocated vmap block just after allocation
mm/vmalloc: get rid of dirty bitmap inside vmap_block structure
mm/vmalloc.c | 94 ++++++++++++++++++++++++++++++++++--------------------------
1 file changed, 54 insertions(+), 40 deletions(-)
Cc: Andrew Morton <[email protected]>
Cc: Nick Piggin <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: WANG Chao <[email protected]>
Cc: Fabian Frederick <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Gioh Kim <[email protected]>
Cc: Rob Jones <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
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1.9.3
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