10:50 a.m.
Use new return type vm_fault_t for fault and huge_fault
handler. For now, this is just documenting that the
function returns a VM_FAULT value rather than an errno.
Once all instances are converted, vm_fault_t will become
a distinct type.
Reference id -> 1c8f422059ae ("mm: change return type to
vm_fault_t")
Previously vm_insert_mixed() returns err which driver
mapped into VM_FAULT_* type. The new function
vmf_insert_mixed() will replace this inefficiency by
returning VM_FAULT_* type.
Signed-off-by: Souptick Joarder <jrdr.linux(a)gmail.com>
Reviewed-by: Matthew Wilcox <mawilcox(a)microsoft.com>
---
v2: Modified the change log
v3: Updated the change log
drivers/dax/device.c | 26 +++++++++++---------------
1 file changed, 11 insertions(+), 15 deletions(-)
diff --git a/drivers/dax/device.c b/drivers/dax/device.c
index 2137dbc..a122701 100644
--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -243,11 +243,11 @@ __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax,
pgoff_t pgoff,
return -1;
}
-static int __dev_dax_pte_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
+static vm_fault_t __dev_dax_pte_fault(struct dev_dax *dev_dax,
+ struct vm_fault *vmf)
{
struct device *dev = &dev_dax->dev;
struct dax_region *dax_region;
- int rc = VM_FAULT_SIGBUS;
phys_addr_t phys;
pfn_t pfn;
unsigned int fault_size = PAGE_SIZE;
@@ -274,17 +274,11 @@ static int __dev_dax_pte_fault(struct dev_dax *dev_dax, struct
vm_fault *vmf)
pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
- rc = vm_insert_mixed(vmf->vma, vmf->address, pfn);
-
- if (rc == -ENOMEM)
- return VM_FAULT_OOM;
- if (rc < 0 && rc != -EBUSY)
- return VM_FAULT_SIGBUS;
-
- return VM_FAULT_NOPAGE;
+ return vmf_insert_mixed(vmf->vma, vmf->address, pfn);
}
-static int __dev_dax_pmd_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
+static vm_fault_t __dev_dax_pmd_fault(struct dev_dax *dev_dax,
+ struct vm_fault *vmf)
{
unsigned long pmd_addr = vmf->address & PMD_MASK;
struct device *dev = &dev_dax->dev;
@@ -335,7 +329,8 @@ static int __dev_dax_pmd_fault(struct dev_dax *dev_dax, struct
vm_fault *vmf)
}
#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
-static int __dev_dax_pud_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
+static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
+ struct vm_fault *vmf)
{
unsigned long pud_addr = vmf->address & PUD_MASK;
struct device *dev = &dev_dax->dev;
@@ -386,13 +381,14 @@ static int __dev_dax_pud_fault(struct dev_dax *dev_dax, struct
vm_fault *vmf)
vmf->flags & FAULT_FLAG_WRITE);
}
#else
-static int __dev_dax_pud_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
+static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
+ struct vm_fault *vmf)
{
return VM_FAULT_FALLBACK;
}
#endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
-static int dev_dax_huge_fault(struct vm_fault *vmf,
+static vm_fault_t dev_dax_huge_fault(struct vm_fault *vmf,
enum page_entry_size pe_size)
{
int rc, id;
@@ -423,7 +419,7 @@ static int dev_dax_huge_fault(struct vm_fault *vmf,
return rc;
}
-static int dev_dax_fault(struct vm_fault *vmf)
+static vm_fault_t dev_dax_fault(struct vm_fault *vmf)
{
return dev_dax_huge_fault(vmf, PE_SIZE_PTE);
}
--
1.9.1
3:02 p.m.
On Tue, Apr 17, 2018 at 12:20:44AM +0530, Souptick Joarder wrote:
Use new return type vm_fault_t for fault and huge_fault
handler. For now, this is just documenting that the
function returns a VM_FAULT value rather than an errno.
Once all instances are converted, vm_fault_t will become
a distinct type.
I'm not sure what you mean by "vm_fault_t will become a distinct type"? Do
you mean you'll make it into an enum, i.e.:
enum vm_fault_t {
VM_FAULT_OOM = 0x0001,
VM_FAULT_SIGBUS = 0x0002,
VM_FAULT_MAJOR = 0x0004,
VM_FAULT_WRITE = 0x0008,
VM_FAULT_HWPOISON = 0x0010,
VM_FAULT_HWPOISON_LARGE = 0x0020,
VM_FAULT_NOPAGE = 0x0100,
VM_FAULT_LOCKED = 0x0200,
VM_FAULT_RETRY = 0x0400,
VM_FAULT_FALLBACK = 0x0800,
VM_FAULT_DONE_COW = 0x1000,
VM_FAULT_NEEDDSYNC = 0x2000,
};
If so, I think that would be great for readability. Right now I look up the
definition of vm_fault_t and see it's typedef'd to an int, and that doesn't
give me as much info as the above enum would.
If this is the plan, I don't understand why you need to make all the site
conversions first?
Reference id -> 1c8f422059ae ("mm: change return type to
vm_fault_t")
Previously vm_insert_mixed() returns err which driver
mapped into VM_FAULT_* type. The new function
vmf_insert_mixed() will replace this inefficiency by
returning VM_FAULT_* type.
Signed-off-by: Souptick Joarder <jrdr.linux(a)gmail.com>
Reviewed-by: Matthew Wilcox <mawilcox(a)microsoft.com>
---
v2: Modified the change log
v3: Updated the change log
You've only got a v2. :)
Sure, the code looks correct. You can add:
Reviewed-by: Ross Zwisler <ross.zwisler(a)linux.intel.com>
3:21 p.m.
On Mon, Apr 16, 2018 at 05:02:00PM -0600, Ross Zwisler wrote:
I'm not sure what you mean by "vm_fault_t will become a
distinct type"? Do
you mean you'll make it into an enum, i.e.:
enum vm_fault_t {
VM_FAULT_OOM = 0x0001,
VM_FAULT_SIGBUS = 0x0002,
VM_FAULT_MAJOR = 0x0004,
VM_FAULT_WRITE = 0x0008,
VM_FAULT_HWPOISON = 0x0010,
VM_FAULT_HWPOISON_LARGE = 0x0020,
VM_FAULT_NOPAGE = 0x0100,
VM_FAULT_LOCKED = 0x0200,
VM_FAULT_RETRY = 0x0400,
VM_FAULT_FALLBACK = 0x0800,
VM_FAULT_DONE_COW = 0x1000,
VM_FAULT_NEEDDSYNC = 0x2000,
};
My current tree has this in it:
+/*
+ * Different kinds of faults, as returned from fault handlers.
+ * Used to decide whether a process gets delivered SIGBUS or
+ * just gets major/minor fault counters bumped up.
+ */
+typedef __bitwise unsigned int vm_fault_t;
+enum {
+ VM_FAULT_OOM = (__force vm_fault_t)0x000001, /* Out Of Memory */
+ VM_FAULT_SIGBUS = (__force vm_fault_t)0x000002, /* Bad access */
+ VM_FAULT_MAJOR = (__force vm_fault_t)0x000004, /* Page read from storage
*/
+ VM_FAULT_WRITE = (__force vm_fault_t)0x000008, /* Special case for
get_user_pages */
+ VM_FAULT_HWPOISON = (__force vm_fault_t)0x000010, /* Hit poisoned small page
*/
+ VM_FAULT_HWPOISON_LARGE = (__force vm_fault_t)0x000020, /* Hit poisoned large
page. Index encoded in upper bits */
+ VM_FAULT_SIGSEGV = (__force vm_fault_t)0x000040,
+ VM_FAULT_NOPAGE = (__force vm_fault_t)0x000100, /* ->fault installed
the pte, not return page */
+ VM_FAULT_LOCKED = (__force vm_fault_t)0x000200, /* ->fault locked the
returned page */
+ VM_FAULT_RETRY = (__force vm_fault_t)0x000400, /* ->fault blocked,
must retry */
+ VM_FAULT_FALLBACK = (__force vm_fault_t)0x000800, /* huge page fault failed,
fall back to small */
+ VM_FAULT_DONE_COW = (__force vm_fault_t)0x001000, /* ->fault has fully
handled COW */
+ VM_FAULT_NEEDDSYNC = (__force vm_fault_t)0x002000, /* ->fault did not
modify page tables
+ * and needs fsync() to complete (for
+ * synchronous page faults in DAX) */
+ VM_FAULT_HINDEX_MASK = (__force vm_fault_t)0x0f0000,
+};
However, I'm hoping to get a better syntax into sparse ;-)
If so, I think that would be great for readability. Right now I look
up the
definition of vm_fault_t and see it's typedef'd to an int, and that doesn't
give me as much info as the above enum would.
If this is the plan, I don't understand why you need to make all the site
conversions first?
Changing it from a signed to an unsigned int causes GCC to warn about
an assignment from an incompatible type -- int foo(void) is incompatible
with unsigned int foo(void).
Sure, the code looks correct. You can add:
Reviewed-by: Ross Zwisler <ross.zwisler(a)linux.intel.com>
Thanks, Ross.
9:21 p.m.
On Tue, Apr 17, 2018 at 4:32 AM, Ross Zwisler
<ross.zwisler(a)linux.intel.com> wrote:
On Tue, Apr 17, 2018 at 12:20:44AM +0530, Souptick Joarder wrote:
> Use new return type vm_fault_t for fault and huge_fault
> handler. For now, this is just documenting that the
> function returns a VM_FAULT value rather than an errno.
> Once all instances are converted, vm_fault_t will become
> a distinct type.
I'm not sure what you mean by "vm_fault_t will become a distinct type"?
Do
you mean you'll make it into an enum, i.e.:
enum vm_fault_t {
VM_FAULT_OOM = 0x0001,
VM_FAULT_SIGBUS = 0x0002,
VM_FAULT_MAJOR = 0x0004,
VM_FAULT_WRITE = 0x0008,
VM_FAULT_HWPOISON = 0x0010,
VM_FAULT_HWPOISON_LARGE = 0x0020,
VM_FAULT_NOPAGE = 0x0100,
VM_FAULT_LOCKED = 0x0200,
VM_FAULT_RETRY = 0x0400,
VM_FAULT_FALLBACK = 0x0800,
VM_FAULT_DONE_COW = 0x1000,
VM_FAULT_NEEDDSYNC = 0x2000,
};
If so, I think that would be great for readability. Right now I look up the
definition of vm_fault_t and see it's typedef'd to an int, and that doesn't
give me as much info as the above enum would.
If this is the plan, I don't understand why you need to make all the site
conversions first?
> Reference id -> 1c8f422059ae ("mm: change return type to
> vm_fault_t")
>
> Previously vm_insert_mixed() returns err which driver
> mapped into VM_FAULT_* type. The new function
> vmf_insert_mixed() will replace this inefficiency by
> returning VM_FAULT_* type.
>
> Signed-off-by: Souptick Joarder <jrdr.linux(a)gmail.com>
> Reviewed-by: Matthew Wilcox <mawilcox(a)microsoft.com>
> ---
> v2: Modified the change log
>
> v3: Updated the change log
You've only got a v2. :)
Sorry about it. I will correct :)
Sure, the code looks correct. You can add:
Reviewed-by: Ross Zwisler <ross.zwisler(a)linux.intel.com>
Thanks.
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