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    Subject[PATCH 04/31] kasan, page_alloc: simplify kasan_poison_pages call site
    Date
    From: Andrey Konovalov <andreyknvl@google.com>

    Simplify the code around calling kasan_poison_pages() in
    free_pages_prepare().

    Reording kasan_poison_pages() and kernel_init_free_pages() is OK,
    since kernel_init_free_pages() can handle poisoned memory.

    This patch does no functional changes besides reordering the calls.

    Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
    ---
    mm/page_alloc.c | 18 +++++-------------
    1 file changed, 5 insertions(+), 13 deletions(-)

    diff --git a/mm/page_alloc.c b/mm/page_alloc.c
    index 3f3ea41f8c64..0673db27dd12 100644
    --- a/mm/page_alloc.c
    +++ b/mm/page_alloc.c
    @@ -1289,6 +1289,7 @@ static __always_inline bool free_pages_prepare(struct page *page,
    {
    int bad = 0;
    bool skip_kasan_poison = should_skip_kasan_poison(page, fpi_flags);
    + bool init = want_init_on_free();

    VM_BUG_ON_PAGE(PageTail(page), page);

    @@ -1359,19 +1360,10 @@ static __always_inline bool free_pages_prepare(struct page *page,
    * With hardware tag-based KASAN, memory tags must be set before the
    * page becomes unavailable via debug_pagealloc or arch_free_page.
    */
    - if (kasan_has_integrated_init()) {
    - bool init = want_init_on_free();
    -
    - if (!skip_kasan_poison)
    - kasan_poison_pages(page, order, init);
    - } else {
    - bool init = want_init_on_free();
    -
    - if (init)
    - kernel_init_free_pages(page, 1 << order);
    - if (!skip_kasan_poison)
    - kasan_poison_pages(page, order, init);
    - }
    + if (!skip_kasan_poison)
    + kasan_poison_pages(page, order, init);
    + if (init && !kasan_has_integrated_init())
    + kernel_init_free_pages(page, 1 << order);

    /*
    * arch_free_page() can make the page's contents inaccessible. s390
    --
    2.25.1
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