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; } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
