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    Subject[PATCH v11 69/69] mm/mmap.c: pass in mapping to __vma_link_file()
    Date
    From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>

    __vma_link_file() resolves the mapping from the file, if there is one.
    Pass through the mapping and check the vm_file externally since most
    places already have the required information and check of vm_file.

    Link: https://lkml.kernel.org/r/20220504011345.662299-54-Liam.Howlett@oracle.com
    Link: https://lkml.kernel.org/r/20220621204632.3370049-70-Liam.Howlett@oracle.com
    Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: David Howells <dhowells@redhat.com>
    Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
    Cc: SeongJae Park <sj@kernel.org>
    Cc: Vlastimil Babka <vbabka@suse.cz>
    Cc: Will Deacon <will@kernel.org>
    Cc: Davidlohr Bueso <dave@stgolabs.net>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    ---
    mm/mmap.c | 33 +++++++++++++++------------------
    1 file changed, 15 insertions(+), 18 deletions(-)

    diff --git a/mm/mmap.c b/mm/mmap.c
    index 1c35cd0ec4c7..d24a3a4b669a 100644
    --- a/mm/mmap.c
    +++ b/mm/mmap.c
    @@ -246,6 +246,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
    if (brk < min_brk)
    goto out;

    +
    /*
    * Check against rlimit here. If this check is done later after the test
    * of oldbrk with newbrk then it can escape the test and let the data
    @@ -322,7 +323,6 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
    if (populate)
    mm_populate(oldbrk, newbrk - oldbrk);
    return brk;
    -
    out:
    mmap_write_unlock(mm);
    return origbrk;
    @@ -454,21 +454,15 @@ static unsigned long count_vma_pages_range(struct mm_struct *mm,
    return nr_pages;
    }

    -static void __vma_link_file(struct vm_area_struct *vma)
    +static void __vma_link_file(struct vm_area_struct *vma,
    + struct address_space *mapping)
    {
    - struct file *file;
    -
    - file = vma->vm_file;
    - if (file) {
    - struct address_space *mapping = file->f_mapping;
    -
    - if (vma->vm_flags & VM_SHARED)
    - mapping_allow_writable(mapping);
    + if (vma->vm_flags & VM_SHARED)
    + mapping_allow_writable(mapping);

    - flush_dcache_mmap_lock(mapping);
    - vma_interval_tree_insert(vma, &mapping->i_mmap);
    - flush_dcache_mmap_unlock(mapping);
    - }
    + flush_dcache_mmap_lock(mapping);
    + vma_interval_tree_insert(vma, &mapping->i_mmap);
    + flush_dcache_mmap_unlock(mapping);
    }

    /*
    @@ -535,10 +529,11 @@ static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma)
    }

    vma_mas_store(vma, &mas);
    - __vma_link_file(vma);

    - if (mapping)
    + if (mapping) {
    + __vma_link_file(vma, mapping);
    i_mmap_unlock_write(mapping);
    + }

    mm->map_count++;
    validate_mm(mm);
    @@ -784,14 +779,14 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
    uprobe_munmap(next, next->vm_start, next->vm_end);

    i_mmap_lock_write(mapping);
    - if (insert) {
    + if (insert && insert->vm_file) {
    /*
    * Put into interval tree now, so instantiated pages
    * are visible to arm/parisc __flush_dcache_page
    * throughout; but we cannot insert into address
    * space until vma start or end is updated.
    */
    - __vma_link_file(insert);
    + __vma_link_file(insert, insert->vm_file->f_mapping);
    }
    }

    @@ -3043,6 +3038,7 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
    struct mm_struct *mm = current->mm;

    validate_mm_mt(mm);
    +
    /*
    * Check against address space limits by the changed size
    * Note: This happens *after* clearing old mappings in some code paths.
    @@ -3100,6 +3096,7 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
    goto mas_store_fail;

    mm->map_count++;
    +
    out:
    perf_event_mmap(vma);
    mm->total_vm += len >> PAGE_SHIFT;
    --
    2.35.1
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