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 <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: WANG Chao <chaowang@xxxxxxxxxx>
Cc: Fabian Frederick <fabf@xxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Gioh Kim <gioh.kim@xxxxxxx>
Cc: Rob Jones <rob.jones@xxxxxxxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
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