Re: [PATCH 2/4] kmemleak: Handle percpu memory allocation

From: Tejun Heo
Date: Tue Oct 04 2011 - 05:13:20 EST


On Tue, Oct 04, 2011 at 10:04:46AM +0100, Catalin Marinas wrote:
> > The percpu part looks fine to me but I don't know how kmemleak works
> > to judge whether the kmemleak part is okay or not. This just avoids
> > false positives from slab and would still require bumping up the early
> > log memory as # of cpus increases, right?
> No, there is only one kmemleak call for each __percpu pointer (to the
> specific kmemleak_*_percpu function). The kmemleak expands the percpu
> pointer into corresponding blocks for each cpu but the early log only
> stores a single call.

Hmmm... but the following definitely seems O(#PCPU_ALLOCS * #CPUS)?
What am I missing?

+ * Log an early allocated block and populate the stack trace.
+ */
+static void early_alloc_percpu(struct early_log *log)
+ unsigned int cpu;
+ const void __percpu *ptr = log->ptr;
+ for_each_possible_cpu(cpu) {
+ log->ptr = per_cpu_ptr(ptr, cpu);
+ early_alloc(log);
+ }


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