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    SubjectRe: Eeek! page_mapcount(page) went negative! (-1)
    Daniel Drake wrote:
    > A user at reported a one-off crash on x86
    > with Here's hoping it might be useful to somebody:
    > Eeek! page_mapcount(page) went negative! (-1)
    > page->flags = 8001003c

    They are PG_s referenced|uptodate|dirty|lru|mappedtodisk

    So it is a regular pagecache page. Even though X is involved,
    I'd be surprised if there is a kernel bug there, but it does
    look like more than a simple single-bit flip.

    > page->count = 1
    > page->mapping = f6ad2418

    If it is a pagecache page, page->mapping != NULL should add 1
    to page->count. Then there should be another reference taken
    for this mapping, and not decremented until after page_remove_rmap.

    So both page_mapcount is wrong (was 0, should be at least 1) and
    either page_count is wrong (was 1, should be at least 2).

    If the page was truncated, dirty, mappedtodisk, and ->mapping
    should have been cleared AFAIKS.

    Oh. I see Arjan's pointed out it is using the nvidia driver (how
    did he figure that out?). That couldn't be helping. If the
    reporter can reproduce without any binary modules loaded, and
    after surviving memtest overnight, it would be very interesting.


    SUSE Labs, Novell Inc.
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      Last update: 2006-07-02 00:06    [W:0.032 / U:2.284 seconds]
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