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    SubjectRe: [PATCH v1 3/7] mm: rename and move page_is_poisoned()
    On Thu, Apr 29, 2021 at 02:25:15PM +0200, David Hildenbrand wrote:
    > Commit d3378e86d182 ("mm/gup: check page posion status for coredump.")
    > introduced page_is_poisoned(), however, v5 [1] of the patch used
    > "page_is_hwpoison()" and something went wrong while upstreaming. Rename the
    > function and move it to page-flags.h, from where it can be used in other
    > -- kcore -- context.
    >
    > Move the comment to the place where it belongs and simplify.
    >
    > [1] https://lkml.kernel.org/r/20210322193318.377c9ce9@alex-virtual-machine
    >
    > Signed-off-by: David Hildenbrand <david@redhat.com>

    Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>

    > ---
    > include/linux/page-flags.h | 7 +++++++
    > mm/gup.c | 6 +++++-
    > mm/internal.h | 20 --------------------
    > 3 files changed, 12 insertions(+), 21 deletions(-)

    Nice :)

    >
    > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
    > index 04a34c08e0a6..b8c56672a588 100644
    > --- a/include/linux/page-flags.h
    > +++ b/include/linux/page-flags.h
    > @@ -694,6 +694,13 @@ PAGEFLAG_FALSE(DoubleMap)
    > TESTSCFLAG_FALSE(DoubleMap)
    > #endif
    >
    > +static inline bool is_page_hwpoison(struct page *page)
    > +{
    > + if (PageHWPoison(page))
    > + return true;
    > + return PageHuge(page) && PageHWPoison(compound_head(page));
    > +}
    > +
    > /*
    > * For pages that are never mapped to userspace (and aren't PageSlab),
    > * page_type may be used. Because it is initialised to -1, we invert the
    > diff --git a/mm/gup.c b/mm/gup.c
    > index ef7d2da9f03f..000f3303e7f2 100644
    > --- a/mm/gup.c
    > +++ b/mm/gup.c
    > @@ -1536,7 +1536,11 @@ struct page *get_dump_page(unsigned long addr)
    > if (locked)
    > mmap_read_unlock(mm);
    >
    > - if (ret == 1 && is_page_poisoned(page))
    > + /*
    > + * We might have hwpoisoned pages still mapped into user space. Don't
    > + * read these pages when creating a coredump, access could be fatal.
    > + */
    > + if (ret == 1 && is_page_hwpoison(page))
    > return NULL;
    >
    > return (ret == 1) ? page : NULL;
    > diff --git a/mm/internal.h b/mm/internal.h
    > index cb3c5e0a7799..1432feec62df 100644
    > --- a/mm/internal.h
    > +++ b/mm/internal.h
    > @@ -97,26 +97,6 @@ static inline void set_page_refcounted(struct page *page)
    > set_page_count(page, 1);
    > }
    >
    > -/*
    > - * When kernel touch the user page, the user page may be have been marked
    > - * poison but still mapped in user space, if without this page, the kernel
    > - * can guarantee the data integrity and operation success, the kernel is
    > - * better to check the posion status and avoid touching it, be good not to
    > - * panic, coredump for process fatal signal is a sample case matching this
    > - * scenario. Or if kernel can't guarantee the data integrity, it's better
    > - * not to call this function, let kernel touch the poison page and get to
    > - * panic.
    > - */
    > -static inline bool is_page_poisoned(struct page *page)
    > -{
    > - if (PageHWPoison(page))
    > - return true;
    > - else if (PageHuge(page) && PageHWPoison(compound_head(page)))
    > - return true;
    > -
    > - return false;
    > -}
    > -
    > extern unsigned long highest_memmap_pfn;
    >
    > /*
    > --
    > 2.30.2
    >

    --
    Sincerely yours,
    Mike.

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