From: David Rientjes rientjes@google.com
upstream 71cdec4fab76667dabdbb2ca232b039004ebd40f commit.
When a DMA coherent pool is depleted, allocation failures may or may not get reported in the kernel log depending on the allocator.
The admin does have a workaround, however, by using coherent_pool= on the kernel command line.
Provide some guidance on the failure and a recommended minimum size for the pools (double the size).
Signed-off-by: David Rientjes rientjes@google.com Tested-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: Peter Gonda pgonda@google.com --- kernel/dma/pool.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c index 8cfa01243ed2..39ca26fa41b5 100644 --- a/kernel/dma/pool.c +++ b/kernel/dma/pool.c @@ -239,12 +239,16 @@ void *dma_alloc_from_pool(struct device *dev, size_t size, }
val = gen_pool_alloc(pool, size); - if (val) { + if (likely(val)) { phys_addr_t phys = gen_pool_virt_to_phys(pool, val);
*ret_page = pfn_to_page(__phys_to_pfn(phys)); ptr = (void *)val; memset(ptr, 0, size); + } else { + WARN_ONCE(1, "DMA coherent pool depleted, increase size " + "(recommended min coherent_pool=%zuK)\n", + gen_pool_size(pool) >> 9); } if (gen_pool_avail(pool) < atomic_pool_size) schedule_work(&atomic_pool_work);