Messages in this thread | | | Date | Thu, 31 Aug 2017 21:11:08 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [patch-rt] drivers/zram: fix zcomp_stream_get() smp_processor_id() use in preemptible code |
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On Wed, 23 Aug 2017, Mike Galbraith wrote:
> > Use get_local_ptr() vs this_cpu_ptr(). > > Signed-off-by: Mike Galbraith <efault@gmx.de> > --- > drivers/block/zram/zcomp.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > --- a/drivers/block/zram/zcomp.c > +++ b/drivers/block/zram/zcomp.c > @@ -120,7 +120,7 @@ struct zcomp_strm *zcomp_stream_get(stru > { > struct zcomp_strm *zstrm; > > - zstrm = *this_cpu_ptr(comp->stream); > + zstrm = *get_local_ptr(comp->stream);
This looks wrong. On mainline the calling code must have preemption disable somehow, otherwise this_cpu_ptr() would not work.
Looking at the call site it is;
zram_slot_lock() bit_spin_lock()
which is of course evading lockdep and everything else debugging wise.
Sebastian, do we have migration protection in bitlocked regions? And we shpuld look into converting that into a spinlock on rt.
Thanks,
tglx
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