[patch 3/8] mm: merge nopfn into fault

akpm
2007-05-18T07:37:07Z

Remove ->nopfn and reimplement the existing handlers with ->fault

[akpm@linux-foundation.org: mpspec.c build fix]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

arch/powerpc/platforms/cell/spufs/file.c | 92 +++++++++++----------
drivers/char/mspec.c | 27 ++++--
include/linux/mm.h | 9 --
mm/memory.c | 58 +------------
4 files changed, 72 insertions(+), 114 deletions(-)

diff -puN arch/powerpc/platforms/cell/spufs/file.c~mm-merge-nopfn-into-fault arch/powerpc/platforms/cell/spufs/file.c
--- a/arch/powerpc/platforms/cell/spufs/file.c~mm-merge-nopfn-into-fault
+++ a/arch/powerpc/platforms/cell/spufs/file.c
@@ -115,8 +115,8 @@ spufs_mem_write(struct file *file, const
return size;
}

-static unsigned long spufs_mem_mmap_nopfn(struct vm_area_struct *vma,
- unsigned long address)
+static struct page *spufs_mem_mmap_fault(struct vm_area_struct *vma,
+ struct fault_data *fdata)
{
struct spu_context *ctx = vma->vm_file->private_data;
unsigned long pfn, offset, addr0 = address;
@@ -137,9 +137,11 @@ static unsigned long spufs_mem_mmap_nopf
}
#endif /* CONFIG_SPU_FS_64K_LS */

- offset = (address - vma->vm_start) + (vma->vm_pgoff << PAGE_SHIFT);
- if (offset >= LS_SIZE)
- return NOPFN_SIGBUS;
+ offset = fdata->pgoff << PAGE_SHIFT
+ if (offset >= LS_SIZE) {
+ fdata->type = VM_FAULT_SIGBUS;
+ return NULL;
+ }

pr_debug("spufs_mem_mmap_nopfn address=0x%lx -> 0x%lx, offset=0x%lx\n",
addr0, address, offset);
@@ -155,16 +157,17 @@ static unsigned long spufs_mem_mmap_nopf
| _PAGE_NO_CACHE);
pfn = (ctx->spu->local_store_phys + offset) >> PAGE_SHIFT;
}
- vm_insert_pfn(vma, address, pfn);
+ vm_insert_pfn(vma, fdata->address, pfn);

spu_release(ctx);

- return NOPFN_REFAULT;
+ fdata->type = VM_FAULT_MINOR;
+ return NULL;
}

static struct vm_operations_struct spufs_mem_mmap_vmops = {
- .nopfn = spufs_mem_mmap_nopfn,
+ .fault = spufs_mem_mmap_fault,
};

static int spufs_mem_mmap(struct file *file, struct vm_area_struct *vma)
@@ -226,42 +229,45 @@ static const struct file_operations spuf
#endif
};

-static unsigned long spufs_ps_nopfn(struct vm_area_struct *vma,
- unsigned long address,
+static struct page *spufs_ps_fault(struct vm_area_struct *vma,
+ struct fault_data *fdata,
unsigned long ps_offs,
unsigned long ps_size)
{
struct spu_context *ctx = vma->vm_file->private_data;
- unsigned long area, offset = address - vma->vm_start;
+ unsigned long area, offset = fdata->pgoff << PAGE_SHIFT;
int ret;

- offset += vma->vm_pgoff << PAGE_SHIFT;
- if (offset >= ps_size)
- return NOPFN_SIGBUS;
+ if (offset >= ps_size) {
+ fdata->type = VM_FAULT_SIGBUS;
+ return NULL;
+ }
+
+ fdata->type = VM_FAULT_MINOR;

/* error here usually means a signal.. we might want to test
* the error code more precisely though
*/
ret = spu_acquire_runnable(ctx, 0);
if (ret)
- return NOPFN_REFAULT;
+ return NULL;

area = ctx->spu->problem_phys + ps_offs;
- vm_insert_pfn(vma, address, (area + offset) >> PAGE_SHIFT);
+ vm_insert_pfn(vma, fdata->address, (area + offset) >> PAGE_SHIFT);
spu_release(ctx);

- return NOPFN_REFAULT;
+ return NULL;
}

#if SPUFS_MMAP_4K
-static unsigned long spufs_cntl_mmap_nopfn(struct vm_area_struct *vma,
- unsigned long address)
+static struct page *spufs_cntl_mmap_fault(struct vm_area_struct *vma,
+ struct fault_data *fdata)
{
- return spufs_ps_nopfn(vma, address, 0x4000, 0x1000);
+ return spufs_ps_fault(vma, fdata, 0x4000, 0x1000);
}

static struct vm_operations_struct spufs_cntl_mmap_vmops = {
- .nopfn = spufs_cntl_mmap_nopfn,
+ .fault = spufs_cntl_mmap_fault,
};

/*
@@ -891,23 +897,23 @@ static ssize_t spufs_signal1_write(struc
return 4;
}

-static unsigned long spufs_signal1_mmap_nopfn(struct vm_area_struct *vma,
- unsigned long address)
+static struct page *spufs_signal1_mmap_fault(struct vm_area_struct *vma,
+ struct fault_data *fdata)
{
#if PAGE_SIZE == 0x1000
- return spufs_ps_nopfn(vma, address, 0x14000, 0x1000);
+ return spufs_ps_fault(vma, fdata, 0x14000, 0x1000);
#elif PAGE_SIZE == 0x10000
/* For 64k pages, both signal1 and signal2 can be used to mmap the whole
* signal 1 and 2 area
*/
- return spufs_ps_nopfn(vma, address, 0x10000, 0x10000);
+ return spufs_ps_fault(vma, fdata, 0x10000, 0x10000);
#else
#error unsupported page size
#endif
}

static struct vm_operations_struct spufs_signal1_mmap_vmops = {
- .nopfn = spufs_signal1_mmap_nopfn,
+ .fault = spufs_signal1_mmap_fault,
};

static int spufs_signal1_mmap(struct file *file, struct vm_area_struct *vma)
@@ -1016,23 +1022,23 @@ static ssize_t spufs_signal2_write(struc
}

#if SPUFS_MMAP_4K
-static unsigned long spufs_signal2_mmap_nopfn(struct vm_area_struct *vma,
- unsigned long address)
+static struct page *spufs_signal2_mmap_fault(struct vm_area_struct *vma,
+ struct fault_data *fdata)
{
#if PAGE_SIZE == 0x1000
- return spufs_ps_nopfn(vma, address, 0x1c000, 0x1000);
+ return spufs_ps_fault(vma, fdata, 0x1c000, 0x1000);
#elif PAGE_SIZE == 0x10000
/* For 64k pages, both signal1 and signal2 can be used to mmap the whole
* signal 1 and 2 area
*/
- return spufs_ps_nopfn(vma, address, 0x10000, 0x10000);
+ return spufs_ps_fault(vma, fdata, 0x10000, 0x10000);
#else
#error unsupported page size
#endif
}

static struct vm_operations_struct spufs_signal2_mmap_vmops = {
- .nopfn = spufs_signal2_mmap_nopfn,
+ .fault = spufs_signal2_mmap_fault,
};

static int spufs_signal2_mmap(struct file *file, struct vm_area_struct *vma)
@@ -1118,14 +1124,14 @@ DEFINE_SIMPLE_ATTRIBUTE(spufs_signal2_ty
spufs_signal2_type_set, "%llu");

#if SPUFS_MMAP_4K
-static unsigned long spufs_mss_mmap_nopfn(struct vm_area_struct *vma,
- unsigned long address)
+static struct page *spufs_mss_mmap_fault(struct vm_area_struct *vma,
+ struct fault_data *fdata)
{
- return spufs_ps_nopfn(vma, address, 0x0000, 0x1000);
+ return spufs_ps_fault(vma, fdata, 0x0000, 0x1000);
}

static struct vm_operations_struct spufs_mss_mmap_vmops = {
- .nopfn = spufs_mss_mmap_nopfn,
+ .fault = spufs_mss_mmap_fault,
};

/*
@@ -1180,14 +1186,14 @@ static const struct file_operations spuf
.mmap = spufs_mss_mmap,
};

-static unsigned long spufs_psmap_mmap_nopfn(struct vm_area_struct *vma,
- unsigned long address)
+static struct page *spufs_psmap_mmap_fault(struct vm_area_struct *vma,
+ struct fault_data *fdata)
{
- return spufs_ps_nopfn(vma, address, 0x0000, 0x20000);
+ return spufs_ps_fault(vma, fdata, 0x0000, 0x20000);
}

static struct vm_operations_struct spufs_psmap_mmap_vmops = {
- .nopfn = spufs_psmap_mmap_nopfn,
+ .fault = spufs_psmap_mmap_fault,
};

/*
@@ -1240,14 +1246,14 @@ static const struct file_operations spuf

#if SPUFS_MMAP_4K
-static unsigned long spufs_mfc_mmap_nopfn(struct vm_area_struct *vma,
- unsigned long address)
+static struct page *spufs_mfc_mmap_fault(struct vm_area_struct *vma,
+ struct fault_data *fdata)
{
- return spufs_ps_nopfn(vma, address, 0x3000, 0x1000);
+ return spufs_ps_fault(vma, fdata, 0x3000, 0x1000);
}

static struct vm_operations_struct spufs_mfc_mmap_vmops = {
- .nopfn = spufs_mfc_mmap_nopfn,
+ .fault = spufs_mfc_mmap_fault,
};

/*
diff -puN drivers/char/mspec.c~mm-merge-nopfn-into-fault drivers/char/mspec.c
--- a/drivers/char/mspec.c~mm-merge-nopfn-into-fault
+++ a/drivers/char/mspec.c
@@ -182,24 +182,25 @@ mspec_close(struct vm_area_struct *vma)

/*
- * mspec_nopfn
+ * mspec_fault
*
* Creates a mspec page and maps it to user space.
*/
-static unsigned long
-mspec_nopfn(struct vm_area_struct *vma, unsigned long address)
+static struct page *
+mspec_fault(struct vm_area_struct *vma, struct fault_data *fdata)
{
unsigned long paddr, maddr;
unsigned long pfn;
- int index;
+ int index = fdata->pgoff;
struct vma_data *vdata = vma->vm_private_data;

- index = (address - vma->vm_start) >> PAGE_SHIFT;
maddr = (volatile unsigned long) vdata->maddr[index];
if (maddr == 0) {
maddr = uncached_alloc_page(numa_node_id());
- if (maddr == 0)
- return NOPFN_OOM;
+ if (maddr == 0) {
+ fdata->type = VM_FAULT_OOM;
+ return NULL;
+ }

spin_lock(&vdata->lock);
if (vdata->maddr[index] == 0) {
@@ -219,13 +220,21 @@ mspec_nopfn(struct vm_area_struct *vma,

pfn = paddr >> PAGE_SHIFT;

- return pfn;
+ fdata->type = VM_FAULT_MINOR;
+ /*
+ * vm_insert_pfn can fail with -EBUSY, but in that case it will
+ * be because another thread has installed the pte first, so it
+ * is no problem.
+ */
+ vm_insert_pfn(vma, fdata->address, pfn);
+
+ return NULL;
}

static struct vm_operations_struct mspec_vm_ops = {
.open = mspec_open,
.close = mspec_close,
- .nopfn = mspec_nopfn
+ .fault = mspec_fault,
};

/*
diff -puN include/linux/mm.h~mm-merge-nopfn-into-fault include/linux/mm.h
--- a/include/linux/mm.h~mm-merge-nopfn-into-fault
+++ a/include/linux/mm.h
@@ -231,8 +231,6 @@ struct vm_operations_struct {
struct fault_data *fdata);
struct page *(*nopage)(struct vm_area_struct *area,
unsigned long address, int *type);
- unsigned long (*nopfn)(struct vm_area_struct *area,
- unsigned long address);
int (*populate)(struct vm_area_struct *area, unsigned long address,
unsigned long len, pgprot_t prot, unsigned long pgoff,
int nonblock);
@@ -686,13 +684,6 @@ static inline int page_mapped(struct pag
#define NOPAGE_OOM ((struct page *) (-1))

/*
- * Error return values for the *_nopfn functions
- */
-#define NOPFN_SIGBUS ((unsigned long) -1)
-#define NOPFN_OOM ((unsigned long) -2)
-#define NOPFN_REFAULT ((unsigned long) -3)
-
-/*
* Different kinds of faults, as returned by handle_mm_fault().
* Used to decide whether a process gets delivered SIGBUS or
* just gets major/minor fault counters bumped up.
diff -puN mm/memory.c~mm-merge-nopfn-into-fault mm/memory.c
--- a/mm/memory.c~mm-merge-nopfn-into-fault
+++ a/mm/memory.c
@@ -1289,6 +1289,11 @@ EXPORT_SYMBOL(vm_insert_page);
*
* This function should only be called from a vm_ops->fault handler, and
* in that case the handler should return NULL.
+ *
+ * vma cannot be a COW mapping.
+ *
+ * As this is called only for pages that do not currently exist, we
+ * do not need to flush old virtual caches or the TLB.
*/
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
unsigned long pfn)
@@ -2450,56 +2455,6 @@ static int do_nonlinear_fault(struct mm_
}

/*
- * do_no_pfn() tries to create a new page mapping for a page without
- * a struct_page backing it
- *
- * As this is called only for pages that do not currently exist, we
- * do not need to flush old virtual caches or the TLB.
- *
- * We enter with non-exclusive mmap_sem (to exclude vma changes,
- * but allow concurrent faults), and pte mapped but not yet locked.
- * We return with mmap_sem still held, but pte unmapped and unlocked.
- *
- * It is expected that the ->nopfn handler always returns the same pfn
- * for a given virtual mapping.
- *
- * Mark this `noinline' to prevent it from bloating the main pagefault code.
- */
-static noinline int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma,
- unsigned long address, pte_t *page_table, pmd_t *pmd,
- int write_access)
-{
- spinlock_t *ptl;
- pte_t entry;
- unsigned long pfn;
- int ret = VM_FAULT_MINOR;
-
- pte_unmap(page_table);
- BUG_ON(!(vma->vm_flags & VM_PFNMAP));
- BUG_ON(is_cow_mapping(vma->vm_flags));
-
- pfn = vma->vm_ops->nopfn(vma, address & PAGE_MASK);
- if (unlikely(pfn == NOPFN_OOM))
- return VM_FAULT_OOM;
- else if (unlikely(pfn == NOPFN_SIGBUS))
- return VM_FAULT_SIGBUS;
- else if (unlikely(pfn == NOPFN_REFAULT))
- return VM_FAULT_MINOR;
-
- page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
-
- /* Only go through if we didn't race with anybody else... */
- if (pte_none(*page_table)) {
- entry = pfn_pte(pfn, vma->vm_page_prot);
- if (write_access)
- entry = maybe_mkwrite(pte_mkdirty(entry), vma);
- set_pte_at(mm, address, page_table, entry);
- }
- pte_unmap_unlock(page_table, ptl);
- return ret;
-}
-
-/*
* Fault of a previously existing named mapping. Repopulate the pte
* from the encoded file_pte if possible. This enables swappable
* nonlinear vmas.
@@ -2570,9 +2525,6 @@ static inline int handle_pte_fault(struc
if (vma->vm_ops->fault || vma->vm_ops->nopage)
return do_linear_fault(mm, vma, address,
pte, pmd, write_access, entry);
- if (unlikely(vma->vm_ops->nopfn))
- return do_no_pfn(mm, vma, address, pte,
- pmd, write_access);
}
return do_anonymous_page(mm, vma, address,
pte, pmd, write_access);
_