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Subject[PATCH 4.13 004/110] nvme-pci: fix host memory buffer allocation fallback
Date
4.13-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Christoph Hellwig <hch@lst.de>

commit 92dc689563170b90ba844b8a2eb95e8a5eda2e83 upstream.

nvme_alloc_host_mem currently contains two loops that are interwinded,
and the outer retry loop turns out to be broken. Fix this by untangling
the two.

Based on a report an initial patch from Akinobu Mita.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Akinobu Mita <akinobu.mita@gmail.com>
Tested-by: Akinobu Mita <akinobu.mita@gmail.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/nvme/host/pci.c | 48 ++++++++++++++++++++++++++++++------------------
1 file changed, 30 insertions(+), 18 deletions(-)

--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1609,18 +1609,16 @@ static void nvme_free_host_mem(struct nv
dev->host_mem_descs = NULL;
}

-static int nvme_alloc_host_mem(struct nvme_dev *dev, u64 min, u64 preferred)
+static int __nvme_alloc_host_mem(struct nvme_dev *dev, u64 preferred,
+ u32 chunk_size)
{
struct nvme_host_mem_buf_desc *descs;
- u32 chunk_size, max_entries, len;
+ u32 max_entries, len;
dma_addr_t descs_dma;
int i = 0;
void **bufs;
u64 size = 0, tmp;

- /* start big and work our way down */
- chunk_size = min(preferred, (u64)PAGE_SIZE << MAX_ORDER);
-retry:
tmp = (preferred + chunk_size - 1);
do_div(tmp, chunk_size);
max_entries = tmp;
@@ -1647,15 +1645,9 @@ retry:
i++;
}

- if (!size || (min && size < min)) {
- dev_warn(dev->ctrl.device,
- "failed to allocate host memory buffer.\n");
+ if (!size)
goto out_free_bufs;
- }

- dev_info(dev->ctrl.device,
- "allocated %lld MiB host memory buffer.\n",
- size >> ilog2(SZ_1M));
dev->nr_host_mem_descs = i;
dev->host_mem_size = size;
dev->host_mem_descs = descs;
@@ -1676,15 +1668,28 @@ out_free_descs:
dma_free_coherent(dev->dev, max_entries * sizeof(*descs), descs,
descs_dma);
out:
- /* try a smaller chunk size if we failed early */
- if (chunk_size >= PAGE_SIZE * 2 && (i == 0 || size < min)) {
- chunk_size /= 2;
- goto retry;
- }
dev->host_mem_descs = NULL;
return -ENOMEM;
}

+static int nvme_alloc_host_mem(struct nvme_dev *dev, u64 min, u64 preferred)
+{
+ u32 chunk_size;
+
+ /* start big and work our way down */
+ for (chunk_size = min_t(u64, preferred, PAGE_SIZE << MAX_ORDER);
+ chunk_size >= PAGE_SIZE * 2;
+ chunk_size /= 2) {
+ if (!__nvme_alloc_host_mem(dev, preferred, chunk_size)) {
+ if (!min || dev->host_mem_size >= min)
+ return 0;
+ nvme_free_host_mem(dev);
+ }
+ }
+
+ return -ENOMEM;
+}
+
static void nvme_setup_host_mem(struct nvme_dev *dev)
{
u64 max = (u64)max_host_mem_size_mb * SZ_1M;
@@ -1712,8 +1717,15 @@ static void nvme_setup_host_mem(struct n
}

if (!dev->host_mem_descs) {
- if (nvme_alloc_host_mem(dev, min, preferred))
+ if (nvme_alloc_host_mem(dev, min, preferred)) {
+ dev_warn(dev->ctrl.device,
+ "failed to allocate host memory buffer.\n");
return;
+ }
+
+ dev_info(dev->ctrl.device,
+ "allocated %lld MiB host memory buffer.\n",
+ dev->host_mem_size >> ilog2(SZ_1M));
}

if (nvme_set_host_mem(dev, enable_bits))

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