From: Jia-Ju Bai <baijiaju1990@xxxxxxxxx> Subject: fs/ocfs2/dlm/dlmdebug.c: fix a sleep-in-atomic-context bug in dlm_print_one_mle() 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@xxxxxxxxx Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Mark Fasheh <mark@xxxxxxxxxx> Cc: Joel Becker <jlbec@xxxxxxxxxxxx> Cc: Junxiao Bi <junxiao.bi@xxxxxxxxxx> Cc: Joseph Qi <jiangqi903@xxxxxxxxx> Cc: Changwei Ge <ge.changwei@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/ocfs2/dlm/dlmdebug.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/ocfs2/dlm/dlmdebug.c~fs-ocfs2-dlm-fix-a-sleep-in-atomic-context-bug-in-dlm_print_one_mle +++ a/fs/ocfs2/dlm/dlmdebug.c @@ -329,7 +329,7 @@ void dlm_print_one_mle(struct dlm_master { 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); _
