On Tue, Oct 28, 2014 at 12:08:46PM -0700, Florian Fainelli wrote: > Hello, > > While debugging why some dma_alloc_coherent() allocations where > returning NULL on our brcmstb platform, specifically with > drivers/net/ethernet/broadcom/bcmcsysport.c, I came across the > fatal_signal_pending() check in mm/page_alloc.c which is there. > > This driver calls dma_alloc_coherent(, GFP_KERNEL) which ends up making > a coherent allocation from a CMA region on our platform. Since that > allocation is allowed to sleep, and because we are in bcm_syport_open(), > executed from process context, a pending signal makes > dma_alloc_coherent() return NULL. Hello, Florian. fatal_signal_pending means that there is SIGKILL on that process. I guess that caller of dma_alloc_coherent() will die soon. In this case, why CMA should be succeed? > > There are two ways I could fix this: > > - use a GFP_ATOMIC allocation, which would avoid this sensitivity to a > pending signal being fatal (we suffer from the same issue in > bcm_sysport_resume) > > - move the DMA coherent allocation before bcm_sysport_open(), in the > driver's probe function, but if the network interface is never used, we > would be waisting precious DMA coherent memory for nothing (it is only 4 > bytes times 32 but still I guess that it is okay that bcm_sysport_open() return -EINTR? Thanks. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>