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    Subject[PATCH 01/10] mm: page_ref_add_unless() does not trace 'u' argument
    Date
    In other page_ref_* functions all arguments and returns are traced, but
    in page_ref_add_unless the 'u' argument which stands for unless boolean
    is not traced. However, what is more confusing is that in the tracing
    routine:
    __page_ref_mod_unless(struct page *page, int v, int u);

    The 'u' argument present, but instead a return value is passed into
    this argument.

    Add a new template specific for page_ref_add_unless(), and trace all
    arguments and the return value.

    Fixes: 95813b8faa0c ("mm/page_ref: add tracepoint to track down page reference manipulation")

    Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
    ---
    include/linux/page_ref.h | 10 ++++----
    include/trace/events/page_ref.h | 43 ++++++++++++++++++++++++++++++---
    mm/debug_page_ref.c | 8 +++---
    3 files changed, 49 insertions(+), 12 deletions(-)

    diff --git a/include/linux/page_ref.h b/include/linux/page_ref.h
    index 2e677e6ad09f..1903af5fb087 100644
    --- a/include/linux/page_ref.h
    +++ b/include/linux/page_ref.h
    @@ -11,7 +11,7 @@ DECLARE_TRACEPOINT(page_ref_set);
    DECLARE_TRACEPOINT(page_ref_mod);
    DECLARE_TRACEPOINT(page_ref_mod_and_test);
    DECLARE_TRACEPOINT(page_ref_mod_and_return);
    -DECLARE_TRACEPOINT(page_ref_mod_unless);
    +DECLARE_TRACEPOINT(page_ref_add_unless);
    DECLARE_TRACEPOINT(page_ref_freeze);
    DECLARE_TRACEPOINT(page_ref_unfreeze);

    @@ -30,7 +30,7 @@ extern void __page_ref_set(struct page *page, int v);
    extern void __page_ref_mod(struct page *page, int v);
    extern void __page_ref_mod_and_test(struct page *page, int v, int ret);
    extern void __page_ref_mod_and_return(struct page *page, int v, int ret);
    -extern void __page_ref_mod_unless(struct page *page, int v, int u);
    +extern void __page_ref_add_unless(struct page *page, int v, int u, int ret);
    extern void __page_ref_freeze(struct page *page, int v, int ret);
    extern void __page_ref_unfreeze(struct page *page, int v);

    @@ -50,7 +50,7 @@ static inline void __page_ref_mod_and_test(struct page *page, int v, int ret)
    static inline void __page_ref_mod_and_return(struct page *page, int v, int ret)
    {
    }
    -static inline void __page_ref_mod_unless(struct page *page, int v, int u)
    +static inline void __page_ref_add_unless(struct page *page, int v, int u, int ret)
    {
    }
    static inline void __page_ref_freeze(struct page *page, int v, int ret)
    @@ -237,8 +237,8 @@ static inline bool page_ref_add_unless(struct page *page, int nr, int u)
    {
    bool ret = atomic_add_unless(&page->_refcount, nr, u);

    - if (page_ref_tracepoint_active(page_ref_mod_unless))
    - __page_ref_mod_unless(page, nr, ret);
    + if (page_ref_tracepoint_active(page_ref_add_unless))
    + __page_ref_add_unless(page, nr, u, ret);
    return ret;
    }

    diff --git a/include/trace/events/page_ref.h b/include/trace/events/page_ref.h
    index 8a99c1cd417b..c32d6d161cdb 100644
    --- a/include/trace/events/page_ref.h
    +++ b/include/trace/events/page_ref.h
    @@ -94,6 +94,43 @@ DECLARE_EVENT_CLASS(page_ref_mod_and_test_template,
    __entry->val, __entry->ret)
    );

    +DECLARE_EVENT_CLASS(page_ref_add_unless_template,
    +
    + TP_PROTO(struct page *page, int v, int u, int ret),
    +
    + TP_ARGS(page, v, u, ret),
    +
    + TP_STRUCT__entry(
    + __field(unsigned long, pfn)
    + __field(unsigned long, flags)
    + __field(int, count)
    + __field(int, mapcount)
    + __field(void *, mapping)
    + __field(int, mt)
    + __field(int, val)
    + __field(int, unless)
    + __field(int, ret)
    + ),
    +
    + TP_fast_assign(
    + __entry->pfn = page_to_pfn(page);
    + __entry->flags = page->flags;
    + __entry->count = page_ref_count(page);
    + __entry->mapcount = page_mapcount(page);
    + __entry->mapping = page->mapping;
    + __entry->mt = get_pageblock_migratetype(page);
    + __entry->val = v;
    + __entry->ret = ret;
    + ),
    +
    + TP_printk("pfn=0x%lx flags=%s count=%d mapcount=%d mapping=%p mt=%d val=%d unless=%d ret=%d",
    + __entry->pfn,
    + show_page_flags(__entry->flags & PAGEFLAGS_MASK),
    + __entry->count,
    + __entry->mapcount, __entry->mapping, __entry->mt,
    + __entry->val, __entry->unless, __entry->ret)
    +);
    +
    DEFINE_EVENT(page_ref_mod_and_test_template, page_ref_mod_and_test,

    TP_PROTO(struct page *page, int v, int ret),
    @@ -108,11 +145,11 @@ DEFINE_EVENT(page_ref_mod_and_test_template, page_ref_mod_and_return,
    TP_ARGS(page, v, ret)
    );

    -DEFINE_EVENT(page_ref_mod_and_test_template, page_ref_mod_unless,
    +DEFINE_EVENT(page_ref_add_unless_template, page_ref_add_unless,

    - TP_PROTO(struct page *page, int v, int ret),
    + TP_PROTO(struct page *page, int v, int u, int ret),

    - TP_ARGS(page, v, ret)
    + TP_ARGS(page, v, u, ret)
    );

    DEFINE_EVENT(page_ref_mod_and_test_template, page_ref_freeze,
    diff --git a/mm/debug_page_ref.c b/mm/debug_page_ref.c
    index f3b2c9d3ece2..1426d6887b01 100644
    --- a/mm/debug_page_ref.c
    +++ b/mm/debug_page_ref.c
    @@ -33,12 +33,12 @@ void __page_ref_mod_and_return(struct page *page, int v, int ret)
    EXPORT_SYMBOL(__page_ref_mod_and_return);
    EXPORT_TRACEPOINT_SYMBOL(page_ref_mod_and_return);

    -void __page_ref_mod_unless(struct page *page, int v, int u)
    +void __page_ref_add_unless(struct page *page, int v, int u, int ret)
    {
    - trace_page_ref_mod_unless(page, v, u);
    + trace_page_ref_add_unless(page, v, u, ret);
    }
    -EXPORT_SYMBOL(__page_ref_mod_unless);
    -EXPORT_TRACEPOINT_SYMBOL(page_ref_mod_unless);
    +EXPORT_SYMBOL(__page_ref_add_unless);
    +EXPORT_TRACEPOINT_SYMBOL(page_ref_add_unless);

    void __page_ref_freeze(struct page *page, int v, int ret)
    {
    --
    2.34.1.400.ga245620fadb-goog
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