On Mon, 2 Mar 2015 10:01:00 -0600 Tom Zanussi <tom.zanu...@linux.intel.com> wrote:
> Add a gfp flag that allows kmalloc() et al to be used in tracing > functions. > > The problem with using kmalloc for tracing is that the tracing > subsystem should be able to trace kmalloc itself, which it can't do > directly because of paths like kmalloc()->trace_kmalloc()->kmalloc() > or kmalloc()->trace_mm_page_alloc()->kmalloc(). This part I don't like at all. Why can't the memory be preallocated when the hist is created (the echo 'hist:...')? kmalloc must never be called from any tracepoint callback. This change is currently a showstopper. -- Steve > > With this flag, tracing code could use a special version of kmalloc() > that sets __GFP_NOTRACE on every allocation it does, while leaving the > normal kmalloc() path untouched. > > This would allow any tracepoint in the kmalloc path to be avoided via > DEFINE_EVENT_CONDITION() redefinitions of those events, which check > for ___GFP_NOTRACE immediately in their execution and break if set, > thereby avoiding the recursion. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
