The patch titled
Subject: ipc/sem: play nicer with large nsops allocations
has been added to the -mm tree. Its filename is
ipc-sem-play-nicer-with-large-nsops-allocations.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ipc-sem-play-nicer-with-large-nsops-allocations.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ipc-sem-play-nicer-with-large-nsops-allocations.patch
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------------------------------------------------------
From: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Subject: ipc/sem: play nicer with large nsops allocations
Replacing semop()'s kmalloc for kvmalloc was originally proposed by
Manfred on the premise that it can be called for large (than order-1)
sizes. For example, while Oracle recommends setting SEMOPM to a _minimum_
of 100, some distros[1] encourage the setting to be a factor of the amount
of db tasks (PROCESSES), which can get fishy for large systems (easily
going beyond 1000).
[1] An Example of Semaphore Settings
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/5/html/Tuning_and_Optimizing_Red_Hat_Enterprise_Linux_for_Oracle_9i_and_10g_Databases/sect-Oracle_9i_and_10g_Tuning_Guide-Setting_Semaphores-An_Example_of_Semaphore_Settings.html
So let's just convert this to kvmalloc, just like the rest of the
allocations we do in ipc. While the fallback vmalloc obviously involves
more overhead, this by far the uncommon path, and it's better for the user
than just erroring out with kmalloc.
Link: http://lkml.kernel.org/r/20170803184136.13855-2-dave@xxxxxxxxxxxx
Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
ipc/sem.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff -puN ipc/sem.c~ipc-sem-play-nicer-with-large-nsops-allocations ipc/sem.c
--- a/ipc/sem.c~ipc-sem-play-nicer-with-large-nsops-allocations
+++ a/ipc/sem.c
@@ -1784,7 +1784,7 @@ SYSCALL_DEFINE4(semtimedop, int, semid,
if (nsops > ns->sc_semopm)
return -E2BIG;
if (nsops > SEMOPM_FAST) {
- sops = kmalloc(sizeof(*sops)*nsops, GFP_KERNEL);
+ sops = kvmalloc(sizeof(*sops)*nsops, GFP_KERNEL);
if (sops == NULL)
return -ENOMEM;
}
@@ -2016,7 +2016,7 @@ out_unlock_free:
rcu_read_unlock();
out_free:
if (sops != fast_sops)
- kfree(sops);
+ kvfree(sops);
return error;
}
_
Patches currently in -mm which might be from dave@xxxxxxxxxxxx are
rbtree-cache-leftmost-node-internally.patch
rbtree-optimize-root-check-during-rebalancing-loop.patch
rbtree-add-some-additional-comments-for-rebalancing-cases.patch
lib-rbtree_testc-make-input-module-parameters.patch
lib-rbtree_testc-add-inorder-traversal-test.patch
lib-rbtree_testc-support-rb_root_cached.patch
sched-fair-replace-cfs_rq-rb_leftmost.patch
sched-deadline-replace-earliest-dl-and-rq-leftmost-caching.patch
locking-rtmutex-replace-top-waiter-and-pi_waiters-leftmost-caching.patch
block-cfq-replace-cfq_rb_root-leftmost-caching.patch
lib-interval_tree-fast-overlap-detection.patch
lib-interval-tree-correct-comment-wrt-generic-flavor.patch
procfs-use-faster-rb_first_cached.patch
fs-epoll-use-faster-rb_first_cached.patch
mem-memcg-cache-rightmost-node.patch
mem-memcg-cache-rightmost-node-fix.patch
block-cfq-cache-rightmost-rb_node.patch
block-cfq-cache-rightmost-rb_node-fix.patch
ipc-sem-drop-sem_checkid-helper.patch
ipc-sem-play-nicer-with-large-nsops-allocations.patch
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