On Tue, 06 Feb 2007 14:19:54 -0800
Sumant Patro <[EMAIL PROTECTED]> wrote:

> Preallocate memory for ioctl processing. This is to avoid situations 
> where ioctl fails for lack of memory (when system under heavy stress).
> The memory pool will have 8*4K, 4*8K and 1*64K memory chunks

mutter.

I suspect all this horror is due to stupidity in the DMA API.

pci_alloc_consistent() just goes and assumes GFP_ATOMIC, whereas
the caller (megasas_mgmt_fw_ioctl) would have been perfectly happy
to use GFP_KERNEL.

I bet this fixes it:



diff -puN include/asm-generic/pci-dma-compat.h~a 
include/asm-generic/pci-dma-compat.h
--- a/include/asm-generic/pci-dma-compat.h~a
+++ a/include/asm-generic/pci-dma-compat.h
@@ -4,6 +4,7 @@
 #ifndef _ASM_GENERIC_PCI_DMA_COMPAT_H
 #define _ASM_GENERIC_PCI_DMA_COMPAT_H
 
+#include <linux/types.h>
 #include <linux/dma-mapping.h>
 
 /* note pci_set_dma_mask isn't here, since it's a public function
@@ -22,6 +23,13 @@ pci_alloc_consistent(struct pci_dev *hwd
        return dma_alloc_coherent(hwdev == NULL ? NULL : &hwdev->dev, size, 
dma_handle, GFP_ATOMIC);
 }
 
+static inline void *
+pci_alloc_consistent_not_stupid(struct pci_dev *hwdev, size_t size,
+                    dma_addr_t *dma_handle, gfp_t flags)
+{
+       return dma_alloc_coherent(hwdev == NULL ? NULL : &hwdev->dev, size, 
dma_handle, flags);
+}
+
 static inline void
 pci_free_consistent(struct pci_dev *hwdev, size_t size,
                    void *vaddr, dma_addr_t dma_handle)
diff -puN drivers/scsi/megaraid/megaraid_sas.c~a 
drivers/scsi/megaraid/megaraid_sas.c
--- a/drivers/scsi/megaraid/megaraid_sas.c~a
+++ a/drivers/scsi/megaraid/megaraid_sas.c
@@ -2655,9 +2655,9 @@ megasas_mgmt_fw_ioctl(struct megasas_ins
         * For each user buffer, create a mirror buffer and copy in
         */
        for (i = 0; i < ioc->sge_count; i++) {
-               kbuff_arr[i] = pci_alloc_consistent(instance->pdev,
+               kbuff_arr[i] = pci_alloc_consistent_not_stupid(instance->pdev,
                                                    ioc->sgl[i].iov_len,
-                                                   &buf_handle);
+                                                   &buf_handle, GFP_KERNEL);
                if (!kbuff_arr[i]) {
                        printk(KERN_DEBUG "megasas: Failed to alloc "
                               "kernel SGL buffer for IOCTL \n");
@@ -2684,8 +2684,9 @@ megasas_mgmt_fw_ioctl(struct megasas_ins
        }
 
        if (ioc->sense_len) {
-               sense = pci_alloc_consistent(instance->pdev, ioc->sense_len,
-                                            &sense_handle);
+               sense = pci_alloc_consistent_nopt_stupid(instance->pdev,
+                                       ioc->sense_len, &sense_handle,
+                                       GFP_KERNEL);
                if (!sense) {
                        error = -ENOMEM;
                        goto out;
_

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