mm/khugepaged: add tracepoint to collapse_file()

"mm_khugepaged_collapse_file" for capturing is_shmem.
Currently, is_shmem is not being captured. Capturing is_shmem is useful
as it can indicate if tmpfs is being used as a backing store instead of
persistent storage. Add the tracepoint in collapse_file() named
"mm_khugepaged_collapse_file" for capturing is_shmem.

[gautammenghani201@gmail.com: swap is_shmem and addr to save space, per Steven Rostedt]
Link: https://lkml.kernel.org/r/20221202201807.182829-1-gautammenghani201@gmail.com
Link: https://lkml.kernel.org/r/20221026052218.148234-1-gautammenghani201@gmail.com
Signed-off-by: Gautam Menghani <gautammenghani201@gmail.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>	[tracing]
Cc: David Hildenbrand <david@redhat.com>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/trace/events/huge_memory.h b/include/trace/events/huge_memory.h
index 760455d..3e6fb05 100644 (file)
--- a/include/trace/events/huge_memory.h
+++ b/include/trace/events/huge_memory.h
@@ -203,5 +203,43 @@ TRACE_EVENT(mm_khugepaged_scan_file,
                __print_symbolic(__entry->result, SCAN_STATUS))
 );
 
+TRACE_EVENT(mm_khugepaged_collapse_file,
+       TP_PROTO(struct mm_struct *mm, struct page *hpage, pgoff_t index,
+                       bool is_shmem, unsigned long addr, struct file *file,
+                       int nr, int result),
+       TP_ARGS(mm, hpage, index, addr, is_shmem, file, nr, result),
+       TP_STRUCT__entry(
+               __field(struct mm_struct *, mm)
+               __field(unsigned long, hpfn)
+               __field(pgoff_t, index)
+               __field(unsigned long, addr)
+               __field(bool, is_shmem)
+               __string(filename, file->f_path.dentry->d_iname)
+               __field(int, nr)
+               __field(int, result)
+       ),
+
+       TP_fast_assign(
+               __entry->mm = mm;
+               __entry->hpfn = hpage ? page_to_pfn(hpage) : -1;
+               __entry->index = index;
+               __entry->addr = addr;
+               __entry->is_shmem = is_shmem;
+               __assign_str(filename, file->f_path.dentry->d_iname);
+               __entry->nr = nr;
+               __entry->result = result;
+       ),
+
+       TP_printk("mm=%p, hpage_pfn=0x%lx, index=%ld, addr=%ld, is_shmem=%d, filename=%s, nr=%d, result=%s",
+               __entry->mm,
+               __entry->hpfn,
+               __entry->index,
+               __entry->addr,
+               __entry->is_shmem,
+               __get_str(filename),
+               __entry->nr,
+               __print_symbolic(__entry->result, SCAN_STATUS))
+);
+
 #endif /* __HUGE_MEMORY_H */
 #include <trace/define_trace.h>

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 913b0f4..78ec277 100644 (file)
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1744,12 +1744,12 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
 {
        struct address_space *mapping = file->f_mapping;
        struct page *hpage;
-       pgoff_t index, end = start + HPAGE_PMD_NR;
+       pgoff_t index = 0, end = start + HPAGE_PMD_NR;
        LIST_HEAD(pagelist);
        XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER);
        int nr_none = 0, result = SCAN_SUCCEED;
        bool is_shmem = shmem_file(file);
-       int nr;
+       int nr = 0;
 
        VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem);
        VM_BUG_ON(start & (HPAGE_PMD_NR - 1));
@@ -2102,7 +2102,8 @@ out:
                mem_cgroup_uncharge(page_folio(hpage));
                put_page(hpage);
        }
-       /* TODO: tracepoints */
+
+       trace_mm_khugepaged_collapse_file(mm, hpage, index, is_shmem, addr, file, nr, result);
        return result;
 }