Add tracepoints to dax_pmd_load_hole(), following the same logging
conventions as the tracepoints in dax_iomap_pmd_fault().
Here is an example PMD fault showing the new tracepoints:
read_big-1393 [007] .... 32.133809: dax_pmd_fault: shared mapping read
address 0x10400000 vm_start 0x10200000 vm_end 0x10600000 pgoff 0x200
max_pgoff 0x1400
read_big-1393 [007] .... 32.134067: dax_pmd_load_hole: shared mapping
read address 0x10400000 zero_page ffffea0002b98000 radix_entry 0x1e
read_big-1393 [007] .... 32.134069: dax_pmd_fault_done: shared mapping
read address 0x10400000 vm_start 0x10200000 vm_end 0x10600000 pgoff 0x200
max_pgoff 0x1400 NOPAGE
Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
---
fs/dax.c | 13 +++++++++----
include/trace/events/fs_dax.h | 32 ++++++++++++++++++++++++++++++++
2 files changed, 41 insertions(+), 4 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index 1aa7616..2824414 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1269,32 +1269,37 @@ static int dax_pmd_load_hole(struct vm_area_struct *vma, pmd_t *pmd,
struct address_space *mapping = vma->vm_file->f_mapping;
unsigned long pmd_addr = address & PMD_MASK;
struct page *zero_page;
+ void *ret = NULL;
spinlock_t *ptl;
pmd_t pmd_entry;
- void *ret;
zero_page = mm_get_huge_zero_page(vma->vm_mm);
if (unlikely(!zero_page))
- return VM_FAULT_FALLBACK;
+ goto fallback;
ret = dax_insert_mapping_entry(mapping, vmf, *entryp, 0,
RADIX_DAX_PMD | RADIX_DAX_HZP);
if (IS_ERR(ret))
- return VM_FAULT_FALLBACK;
+ goto fallback;
*entryp = ret;
ptl = pmd_lock(vma->vm_mm, pmd);
if (!pmd_none(*pmd)) {
spin_unlock(ptl);
- return VM_FAULT_FALLBACK;
+ goto fallback;
}
pmd_entry = mk_pmd(zero_page, vma->vm_page_prot);
pmd_entry = pmd_mkhuge(pmd_entry);
set_pmd_at(vma->vm_mm, pmd_addr, pmd, pmd_entry);
spin_unlock(ptl);
+ trace_dax_pmd_load_hole(vma, address, zero_page, ret);
return VM_FAULT_NOPAGE;
+
+fallback:
+ trace_dax_pmd_load_hole_fallback(vma, address, zero_page, ret);
+ return VM_FAULT_FALLBACK;
}
int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address,
diff --git a/include/trace/events/fs_dax.h b/include/trace/events/fs_dax.h
index f9ed4eb..8814b1a 100644
--- a/include/trace/events/fs_dax.h
+++ b/include/trace/events/fs_dax.h
@@ -54,6 +54,38 @@ DEFINE_EVENT(dax_pmd_fault_class, name, \
DEFINE_PMD_FAULT_EVENT(dax_pmd_fault);
DEFINE_PMD_FAULT_EVENT(dax_pmd_fault_done);
+DECLARE_EVENT_CLASS(dax_pmd_load_hole_class,
+ TP_PROTO(struct vm_area_struct *vma, unsigned long address,
+ struct page *zero_page, void *radix_entry),
+ TP_ARGS(vma, address, zero_page, radix_entry),
+ TP_STRUCT__entry(
+ __field(unsigned long, vm_flags)
+ __field(unsigned long, address)
+ __field(struct page *, zero_page)
+ __field(void *, radix_entry)
+ ),
+ TP_fast_assign(
+ __entry->vm_flags = vma->vm_flags;
+ __entry->address = address;
+ __entry->zero_page = zero_page;
+ __entry->radix_entry = radix_entry;
+ ),
+ TP_printk("%s mapping read address %#lx zero_page %p radix_entry %#lx",
+ __entry->vm_flags & VM_SHARED ? "shared" : "private",
+ __entry->address,
+ __entry->zero_page,
+ (unsigned long)__entry->radix_entry
+ )
+)
+
+#define DEFINE_PMD_LOAD_HOLE_EVENT(name) \
+DEFINE_EVENT(dax_pmd_load_hole_class, name, \
+ TP_PROTO(struct vm_area_struct *vma, unsigned long address, \
+ struct page *zero_page, void *radix_entry), \
+ TP_ARGS(vma, address, zero_page, radix_entry))
+
+DEFINE_PMD_LOAD_HOLE_EVENT(dax_pmd_load_hole);
+DEFINE_PMD_LOAD_HOLE_EVENT(dax_pmd_load_hole_fallback);
#endif /* _TRACE_FS_DAX_H */
--
2.7.4
--
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