[PATCH v1 3/7] mm: rename and move page_is_poisoned()

David Hildenbrand
2021-04-29T12:25:56Z

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

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