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    Subject[PATCH v4 38/66] coredump: Remove vma linked list walk
    Date
    From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

    Use the Maple Tree iterator instead. This is too complicated for the
    VMA iterator to handle, so let's open-code it for now. If this turns
    out to be a common pattern, we can migrate it to common code.

    Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
    Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
    ---
    fs/coredump.c | 33 ++++++++++++---------------------
    1 file changed, 12 insertions(+), 21 deletions(-)

    diff --git a/fs/coredump.c b/fs/coredump.c
    index a6b3c196cdef..59347e42048d 100644
    --- a/fs/coredump.c
    +++ b/fs/coredump.c
    @@ -997,30 +997,20 @@ static unsigned long vma_dump_size(struct vm_area_struct *vma,
    return vma->vm_end - vma->vm_start;
    }

    -static struct vm_area_struct *first_vma(struct task_struct *tsk,
    - struct vm_area_struct *gate_vma)
    -{
    - struct vm_area_struct *ret = tsk->mm->mmap;
    -
    - if (ret)
    - return ret;
    - return gate_vma;
    -}
    -
    /*
    * Helper function for iterating across a vma list. It ensures that the caller
    * will visit `gate_vma' prior to terminating the search.
    */
    -static struct vm_area_struct *next_vma(struct vm_area_struct *this_vma,
    +static struct vm_area_struct *coredump_next_vma(struct ma_state *mas,
    + struct vm_area_struct *vma,
    struct vm_area_struct *gate_vma)
    {
    - struct vm_area_struct *ret;
    -
    - ret = this_vma->vm_next;
    - if (ret)
    - return ret;
    - if (this_vma == gate_vma)
    + if (vma == gate_vma)
    return NULL;
    +
    + vma = mas_next(mas, ULONG_MAX);
    + if (vma)
    + return vma;
    return gate_vma;
    }

    @@ -1032,9 +1022,10 @@ int dump_vma_snapshot(struct coredump_params *cprm, int *vma_count,
    struct core_vma_metadata **vma_meta,
    size_t *vma_data_size_ptr)
    {
    - struct vm_area_struct *vma, *gate_vma;
    + struct vm_area_struct *gate_vma, *vma = NULL;
    struct mm_struct *mm = current->mm;
    - int i;
    + MA_STATE(mas, &mm->mm_mt, 0, 0);
    + int i = 0;
    size_t vma_data_size = 0;

    /*
    @@ -1054,8 +1045,7 @@ int dump_vma_snapshot(struct coredump_params *cprm, int *vma_count,
    return -ENOMEM;
    }

    - for (i = 0, vma = first_vma(current, gate_vma); vma != NULL;
    - vma = next_vma(vma, gate_vma), i++) {
    + while ((vma = coredump_next_vma(&mas, vma, gate_vma)) != NULL) {
    struct core_vma_metadata *m = (*vma_meta) + i;

    m->start = vma->vm_start;
    @@ -1064,6 +1054,7 @@ int dump_vma_snapshot(struct coredump_params *cprm, int *vma_count,
    m->dump_size = vma_dump_size(vma, cprm->mm_flags);

    vma_data_size += m->dump_size;
    + i++;
    }

    mmap_write_unlock(mm);
    --
    2.30.2
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