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Commit 4dae560f authored by Ananth N Mavinakayanahalli's avatar Ananth N Mavinakayanahalli Committed by Ingo Molnar
Browse files

kprobes: Sanitize struct kretprobe_instance allocations 

For as long as kretprobes have existed, we've allocated NR_CPUS
instances of kretprobe_instance structures. With the default
value of CONFIG_NR_CPUS increasing on certain architectures, we
are potentially wasting kernel memory.

See http://sourceware.org/bugzilla/show_bug.cgi?id=10839#c3

 for
more details.

Use a saner num_possible_cpus() instead of NR_CPUS for
allocation.

Signed-off-by: default avatarAnanth N Mavinakayanahalli <ananth@in.ibm.com>
Acked-by: default avatarMasami Hiramatsu <mhiramat@redhat.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: fweisbec@gmail.com
LKML-Reference: <20091030135310.GA22230@in.ibm.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 5e9b3972

kernel/kprobes.c

+2 −2
Original line number Diff line number Diff line
@@ -1014,9 +1014,9 @@ int __kprobes register_kretprobe(struct kretprobe *rp) 
	/* Pre-allocate memory for max kretprobe instances */

	if (rp->maxactive <= 0) {

#ifdef CONFIG_PREEMPT

		rp->maxactive = max(10, 2 * NR_CPUS);

		rp->maxactive = max(10, 2 * num_possible_cpus());

#else

		rp->maxactive = NR_CPUS;

		rp->maxactive = num_possible_cpus();

#endif

	}

	spin_lock_init(&rp->lock);