[Bug 261707] panic: vm_page_free_prep: freeing mapped page 0xfffffe0006f80170 on 14-Current(master-n252892-e30fceb89b7)

From: <bugzilla-noreply_at_freebsd.org>
Date: Thu, 10 Feb 2022 14:55:49 UTC
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=261707

--- Comment #4 from commit-hook@FreeBSD.org ---
A commit in branch main references this bug:

URL:
https://cgit.FreeBSD.org/src/commit/?id=b51927b7b018d268c91b2127d82786caf68254de

commit b51927b7b018d268c91b2127d82786caf68254de
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2022-02-10 14:50:42 +0000
Commit:     Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2022-02-10 14:55:10 +0000

    Revert "vm_pageout_scans: correct detection of active object"

    This reverts commit 3de96d664aaaf8e3fb1ca4fc4bd864d2cf734b24.

    Problem is that it is possible to reach the state with ref_count ==
    1 for the mapped non-anonymous object. For instance, anonymous posix
    shmfd or linux shmfs object could be mapped, and then corresponding
    file descriptor closed, dropping the object reference owned by the
    shmfd/shmfs file.  Then the check in inactive scan assumes that the
    object and page are not mapped and frees the page, while they are not.

    PR:     261707
    Discussed with: markj
    Sponsored by:   The FreeBSD Foundation
    MFC after:      now

 sys/vm/vm_pageout.c | 56 +++++++++++++++++------------------------------------
 1 file changed, 18 insertions(+), 38 deletions(-)

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