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    Subject[PATCH 4.19 147/306] fs/ocfs2/dlm/dlmdebug.c: fix a sleep-in-atomic-context bug in dlm_print_one_mle()
    Date
    From: Jia-Ju Bai <baijiaju1990@gmail.com>

    [ Upstream commit 999865764f5f128896402572b439269acb471022 ]

    The kernel module may sleep with holding a spinlock.

    The function call paths (from bottom to top) in Linux-4.16 are:

    [FUNC] get_zeroed_page(GFP_NOFS)
    fs/ocfs2/dlm/dlmdebug.c, 332: get_zeroed_page in dlm_print_one_mle
    fs/ocfs2/dlm/dlmmaster.c, 240: dlm_print_one_mle in __dlm_put_mle
    fs/ocfs2/dlm/dlmmaster.c, 255: __dlm_put_mle in dlm_put_mle
    fs/ocfs2/dlm/dlmmaster.c, 254: spin_lock in dlm_put_ml

    [FUNC] get_zeroed_page(GFP_NOFS)
    fs/ocfs2/dlm/dlmdebug.c, 332: get_zeroed_page in dlm_print_one_mle
    fs/ocfs2/dlm/dlmmaster.c, 240: dlm_print_one_mle in __dlm_put_mle
    fs/ocfs2/dlm/dlmmaster.c, 222: __dlm_put_mle in dlm_put_mle_inuse
    fs/ocfs2/dlm/dlmmaster.c, 219: spin_lock in dlm_put_mle_inuse

    To fix this bug, GFP_NOFS is replaced with GFP_ATOMIC.

    This bug is found by my static analysis tool DSAC.

    Link: http://lkml.kernel.org/r/20180901112528.27025-1-baijiaju1990@gmail.com
    Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
    Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
    Cc: Mark Fasheh <mark@fasheh.com>
    Cc: Joel Becker <jlbec@evilplan.org>
    Cc: Junxiao Bi <junxiao.bi@oracle.com>
    Cc: Joseph Qi <jiangqi903@gmail.com>
    Cc: Changwei Ge <ge.changwei@h3c.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    fs/ocfs2/dlm/dlmdebug.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/fs/ocfs2/dlm/dlmdebug.c b/fs/ocfs2/dlm/dlmdebug.c
    index 9b984cae4c4e0..1d6dc8422899b 100644
    --- a/fs/ocfs2/dlm/dlmdebug.c
    +++ b/fs/ocfs2/dlm/dlmdebug.c
    @@ -329,7 +329,7 @@ void dlm_print_one_mle(struct dlm_master_list_entry *mle)
    {
    char *buf;

    - buf = (char *) get_zeroed_page(GFP_NOFS);
    + buf = (char *) get_zeroed_page(GFP_ATOMIC);
    if (buf) {
    dump_mle(mle, buf, PAGE_SIZE - 1);
    free_page((unsigned long)buf);
    --
    2.20.1


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