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    SubjectRe: [PATCH] mm/page_alloc: silence a KASAN false positive
    On Wed, Jun 10, 2020 at 01:02:04PM +0200, Alexander Potapenko wrote:
    > On Wed, Jun 10, 2020 at 7:55 AM Dmitry Vyukov <dvyukov@google.com> wrote:
    > >
    > > On Wed, Jun 10, 2020 at 7:22 AM Qian Cai <cai@lca.pw> wrote:
    > > >
    > > > kernel_init_free_pages() will use memset() on s390 to clear all pages
    > > > from kmalloc_order() which will override KASAN redzones because a
    > > > redzone was setup from the end of the allocation size to the end of the
    > > > last page. Silence it by not reporting it there. An example of the
    > > > report is,
    > >
    > > Interesting. The reason why we did not hit it on x86_64 is because
    > > clear_page is implemented in asm (arch/x86/lib/clear_page_64.S) and
    > > thus is not instrumented. Arm64 probably does the same. However, on
    > > s390 clear_page is defined to memset.
    >
    > Can we define it to __memset() instead?
    > __memset() is supposed to be ignored by KASAN, e.g. KASAN runtime uses
    > it in the places where we don't care about bugs.

    I suppose that could work if s390 maintains perfer this way.

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