Adding Robin, Yu and swiotlb list.
Hi Greg,
There is an on-going discussion whether to revert this patch, because it breaks a corner case in MIPS when many kernel CONFIGs are not enabled (related to PCI and device). As a result, MIPS pre-allocates only PAGE_SIZE buffer as swiotlb.
https://lore.kernel.org/all/20220820012031.1285979-1-yuzhao@google.com/
However, the core idea of the patch is to panic on purpose if the swiotlb is configured with <1MB memory, in order to sync with the remap failure handler in swiotlb_init_remap().
Therefore, I am waiting for suggestion from Christoph whether (1) to revert this patch, or (2) enforce the restriction to disallow <1MB allocation.
Thank you very much!
Dongli Zhang
On 8/23/22 1:03 AM, Greg Kroah-Hartman wrote:
From: Dongli Zhang dongli.zhang@oracle.com
[ Upstream commit 0bf28fc40d89b1a3e00d1b79473bad4e9ca20ad1 ]
Panic on purpose if nslabs is too small, in order to sync with the remap retry logic.
In addition, print the number of bytes for tlb alloc failure.
Signed-off-by: Dongli Zhang dongli.zhang@oracle.com Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: Sasha Levin sashal@kernel.org
kernel/dma/swiotlb.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 5830dce6081b..f5304e2f6a35 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -242,6 +242,9 @@ void __init swiotlb_init_remap(bool addressing_limit, unsigned int flags, if (swiotlb_force_disable) return;
- if (nslabs < IO_TLB_MIN_SLABS)
panic("%s: nslabs = %lu too small\n", __func__, nslabs);- /*
- By default allocate the bounce buffer memory from low memory, but
- allow to pick a location everywhere for hypervisors with guest
@@ -254,7 +257,8 @@ void __init swiotlb_init_remap(bool addressing_limit, unsigned int flags, else tlb = memblock_alloc_low(bytes, PAGE_SIZE); if (!tlb) {
pr_warn("%s: failed to allocate tlb structure\n", __func__);
pr_warn("%s: Failed to allocate %zu bytes tlb structure\n",__func__, bytes);