[2/2] scsi: mpi3mr: Avoid MAX_PARE_ORDER WARNING for buffer allocations

Commit fc4444941140 ("scsi: mpi3mr: HDB allocation and posting for
hardware and firmware buffers") added mpi3mr_alloc_diag_bufs() which
calls dma_alloc_coherent() to allocate the trace buffer and the firmware
buffer. mpi3mr_alloc_diag_bufs() decides the buffer sizes from the
driver configuration. In my environment, the sizes are 8MB. With the
sizes, dma_alloc_coherent() fails and report this WARNING:

    WARNING: CPU: 4 PID: 438 at mm/page_alloc.c:4676 __alloc_pages_noprof+0x52f/0x640

The WARNING indicates that the order of the allocation size is larger
than MAX_PAGE_ORDER. After this failure, mpi3mr_alloc_diag_bufs()
reduces the buffer sizes and retries dma_alloc_coherent(). In the end,
the buffer allocations succeed with 4MB size in my environment, which
corresponds to MAX_PAGE_ORDER=10. Though the allocations succeed, the
WARNING message is misleading and should be avoided.

To avoid the WARNING, check the orders of the buffer allocation sizes
before calling dma_alloc_coherent(). If the orders are larger than
MAX_PAGE_ORDER, fall back to the retry path.

Fixes: fc4444941140 ("scsi: mpi3mr: HDB allocation and posting for hardware and firmware buffers")
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
---
 drivers/scsi/mpi3mr/mpi3mr_app.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

On Fri, Aug 9, 2024 at 10:27 PM Shin'ichiro Kawasaki
<shinichiro.kawasaki@wdc.com> wrote:
>
> Commit fc4444941140 ("scsi: mpi3mr: HDB allocation and posting for
> hardware and firmware buffers") added mpi3mr_alloc_diag_bufs() which
> calls dma_alloc_coherent() to allocate the trace buffer and the firmware
> buffer. mpi3mr_alloc_diag_bufs() decides the buffer sizes from the
> driver configuration. In my environment, the sizes are 8MB. With the
> sizes, dma_alloc_coherent() fails and report this WARNING:
>
>     WARNING: CPU: 4 PID: 438 at mm/page_alloc.c:4676 __alloc_pages_noprof+0x52f/0x640
>
> The WARNING indicates that the order of the allocation size is larger
> than MAX_PAGE_ORDER. After this failure, mpi3mr_alloc_diag_bufs()
> reduces the buffer sizes and retries dma_alloc_coherent(). In the end,
> the buffer allocations succeed with 4MB size in my environment, which
> corresponds to MAX_PAGE_ORDER=10. Though the allocations succeed, the
> WARNING message is misleading and should be avoided.
>
> To avoid the WARNING, check the orders of the buffer allocation sizes
> before calling dma_alloc_coherent(). If the orders are larger than
> MAX_PAGE_ORDER, fall back to the retry path.
>
> Fixes: fc4444941140 ("scsi: mpi3mr: HDB allocation and posting for hardware and firmware buffers")
> Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
> ---

Acked-by: Sathya Prakash Veerichetty <sathya.prakash@broadcom.com>

>  drivers/scsi/mpi3mr/mpi3mr_app.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/scsi/mpi3mr/mpi3mr_app.c b/drivers/scsi/mpi3mr/mpi3mr_app.c
> index 8b0eded6ef36..01f035f9330e 100644
> --- a/drivers/scsi/mpi3mr/mpi3mr_app.c
> +++ b/drivers/scsi/mpi3mr/mpi3mr_app.c
> @@ -100,7 +100,8 @@ void mpi3mr_alloc_diag_bufs(struct mpi3mr_ioc *mrioc)
>                         dprint_init(mrioc,
>                             "trying to allocate trace diag buffer of size = %dKB\n",
>                             trace_size / 1024);
> -               if (mpi3mr_alloc_trace_buffer(mrioc, trace_size)) {
> +               if (get_order(trace_size) > MAX_PAGE_ORDER ||
> +                   mpi3mr_alloc_trace_buffer(mrioc, trace_size)) {
>                         retry = true;
>                         trace_size -= trace_dec_size;
>                         dprint_init(mrioc, "trace diag buffer allocation failed\n"
> @@ -118,8 +119,12 @@ void mpi3mr_alloc_diag_bufs(struct mpi3mr_ioc *mrioc)
>         diag_buffer->type = MPI3_DIAG_BUFFER_TYPE_FW;
>         diag_buffer->status = MPI3MR_HDB_BUFSTATUS_NOT_ALLOCATED;
>         if ((mrioc->facts.diag_fw_sz < fw_size) && (fw_size >= fw_min_size)) {
> -               diag_buffer->addr = dma_alloc_coherent(&mrioc->pdev->dev,
> -                   fw_size, &diag_buffer->dma_addr, GFP_KERNEL);
> +               if (get_order(fw_size) <= MAX_PAGE_ORDER) {
> +                       diag_buffer->addr
> +                               = dma_alloc_coherent(&mrioc->pdev->dev, fw_size,
> +                                                    &diag_buffer->dma_addr,
> +                                                    GFP_KERNEL);
> +               }
>                 if (!retry)
>                         dprint_init(mrioc,
>                             "%s:trying to allocate firmware diag buffer of size = %dKB\n",
> --
> 2.45.2
>

I made a spell mistake in the commit title:

  s/MAX_PARE_ORDER/MAX_PAGE_ORDER/

Martin, if this patch gets applied as it is, could you fix the mistake?
If you want me to repost with the fix, please let me know.

Shinichiro,

>   s/MAX_PARE_ORDER/MAX_PAGE_ORDER/

I fixed it up, thanks!