From: David Rientjes <rientjes@xxxxxxxxxx>
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@xxxxxxxxxx>
Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Peter Gonda <pgonda@xxxxxxxxxx>
---
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);
--
2.28.0.618.gf4bc123cb7-goog
