On 01/04/2017 02:22 AM, Krister Johansen wrote: > On a kernel with DEBUG_LOCKS, ioat_free_chan_resources triggers an > in_interrupt() warning. With PROVE_LOCKING, it reports detecting a > SOFTIRQ-safe to SOFTIRQ-unsafe lock ordering in the same code path. > > This is because dma_generic_alloc_coherent() checks if the GFP flags > permit blocking. It allocates from different subsystems if blocking is > permitted. The free path knows how to return the memory to the correct > allocator. If GFP_KERNEL is specified then the alloc and free end up > going through cma_alloc(), which uses mutexes. > > Given that ioat_free_chan_resources() can be called in interrupt > context, ioat_alloc_chan_resources() must specify GFP_NOWAIT so that the > allocations do not block and instead use an allocator that uses > spinlocks. > > Signed-off-by: Krister Johansen <kjlx@xxxxxxxxxxxxxxxxxx> Acked-by: Dave Jiang <dave.jiang@xxxxxxxxx> > --- > drivers/dma/ioat/init.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/dma/ioat/init.c b/drivers/dma/ioat/init.c > index 90eddd9..823cdb9 100644 > --- a/drivers/dma/ioat/init.c > +++ b/drivers/dma/ioat/init.c > @@ -693,7 +693,7 @@ static int ioat_alloc_chan_resources(struct dma_chan *c) > /* doing 2 32bit writes to mmio since 1 64b write doesn't work */ > ioat_chan->completion = > dma_pool_zalloc(ioat_chan->ioat_dma->completion_pool, > - GFP_KERNEL, &ioat_chan->completion_dma); > + GFP_NOWAIT, &ioat_chan->completion_dma); > if (!ioat_chan->completion) > return -ENOMEM; > > @@ -703,7 +703,7 @@ static int ioat_alloc_chan_resources(struct dma_chan *c) > ioat_chan->reg_base + IOAT_CHANCMP_OFFSET_HIGH); > > order = IOAT_MAX_ORDER; > - ring = ioat_alloc_ring(c, order, GFP_KERNEL); > + ring = ioat_alloc_ring(c, order, GFP_NOWAIT); > if (!ring) > return -ENOMEM; > > -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
