slab: cleanup mem hotplug synchronization
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- v2 Latest2 patches 1 replyIn review
- v13 patches 3 repliesSuperseded
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| # | Subject and files | Size | Replies | Applied |
|---|---|---|---|---|
| 1/2 | mem-hotplug: implement get/put_online_memsinclude/ include/ mm/ +4 more | +116 | 1 reply | |
| 2/2 | slab: get_online_mems for kmem_cache_{create,destroy,shrink}mm/ mm/ mm/ +2 more | +39 | 0 replies |
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Cover letter [PATCH -mm v2 0/2] slab: cleanup mem hotplug synchronization
Hi,
kmem_cache_{create,destroy,shrink} need to get a stable value of cpu/node online mask, because they init/destroy/access per-cpu/node kmem_cache parts, which can be allocated or destroyed on cpu/mem hotplug. To protect against cpu hotplug, these functions use {get,put}_online_cpus. However, they do nothing to synchronize with memory hotplug - taking the slab_mutex does not eliminate the possibility of race as described in patch 2.
What we need there is something like get_online_cpus, but for memory. We already have lock_memory_hotplug, which serves for the purpose, but it's a bit of a hammer right now, because it's backed by a mutex. As a result, it imposes some limitations to locking order, which are not desirable, and can't be used just like get_online_cpus. That's why in patch 1 I substitute it with get/put_online_mems, which work exactly like get/put_online_cpus except they block not cpu, but memory hotplug.
[ v1 can be found at https://lkml.org/lkml/2014/4/6/68. I NAK'ed it by myself, because it used an rw semaphore for get/put_online_mems, making them dead lock prune. ]
Thanks,
Vladimir Davydov (2):
mem-hotplug: implement get/put_online_mems
slab: lock_memory_hotplug for kmem_cache_{create,destroy,shrink}
include/linux/memory_hotplug.h | 14 ++-- include/linux/mmzone.h | 8 +-- mm/kmemleak.c | 4 +- mm/memory-failure.c | 8 +-- mm/memory_hotplug.c | 142 ++++++++++++++++++++++++++++------------ mm/slab.c | 26 +------- mm/slab.h | 1 + mm/slab_common.c | 35 +++++++++- mm/slob.c | 3 +- mm/slub.c | 9 ++- mm/vmscan.c | 2 +- 11 files changed, 155 insertions(+), 97 deletions(-)
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