The patch titled Subject: fs/ocfs2: fix race in ocfs2_dentry_attach_lock() has been removed from the -mm tree. Its filename was fs-ocfs2-fix-race-in-ocfs2_dentry_attach_lock.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Wengang Wang <wen.gang.wang@xxxxxxxxxx> Subject: fs/ocfs2: fix race in ocfs2_dentry_attach_lock() ocfs2_dentry_attach_lock() can be executed in parallel threads against the same dentry. Make that race safe. The race is like this: thread A thread B (A1) enter ocfs2_dentry_attach_lock, seeing dentry->d_fsdata is NULL, and no alias found by ocfs2_find_local_alias, so kmalloc a new ocfs2_dentry_lock structure to local variable "dl", dl1 ..... (B1) enter ocfs2_dentry_attach_lock, seeing dentry->d_fsdata is NULL, and no alias found by ocfs2_find_local_alias so kmalloc a new ocfs2_dentry_lock structure to local variable "dl", dl2. ...... (A2) set dentry->d_fsdata with dl1, call ocfs2_dentry_lock() and increase dl1->dl_lockres.l_ro_holders to 1 on success. ...... (B2) set dentry->d_fsdata with dl2 call ocfs2_dentry_lock() and increase dl2->dl_lockres.l_ro_holders to 1 on success. ...... (A3) call ocfs2_dentry_unlock() and decrease dl2->dl_lockres.l_ro_holders to 0 on success. .... (B3) call ocfs2_dentry_unlock(), decreasing dl2->dl_lockres.l_ro_holders, but see it's zero now, panic Link: http://lkml.kernel.org/r/20190529174636.22364-1-wen.gang.wang@xxxxxxxxxx Signed-off-by: Wengang Wang <wen.gang.wang@xxxxxxxxxx> Reported-by: Daniel Sobe <daniel.sobe@xxxxxxx> Tested-by: Daniel Sobe <daniel.sobe@xxxxxxx> Reviewed-by: Changwei Ge <gechangwei@xxxxxxx> Reviewed-by: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx> Cc: Mark Fasheh <mark@xxxxxxxxxx> Cc: Joel Becker <jlbec@xxxxxxxxxxxx> Cc: Junxiao Bi <junxiao.bi@xxxxxxxxxx> Cc: Gang He <ghe@xxxxxxxx> Cc: Jun Piao <piaojun@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/ocfs2/dcache.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) --- a/fs/ocfs2/dcache.c~fs-ocfs2-fix-race-in-ocfs2_dentry_attach_lock +++ a/fs/ocfs2/dcache.c @@ -296,6 +296,18 @@ int ocfs2_dentry_attach_lock(struct dent out_attach: spin_lock(&dentry_attach_lock); + if (unlikely(dentry->d_fsdata && !alias)) { + /* d_fsdata is set by a racing thread which is doing + * the same thing as this thread is doing. Leave the racing + * thread going ahead and we return here. + */ + spin_unlock(&dentry_attach_lock); + iput(dl->dl_inode); + ocfs2_lock_res_free(&dl->dl_lockres); + kfree(dl); + return 0; + } + dentry->d_fsdata = dl; dl->dl_count++; spin_unlock(&dentry_attach_lock); _ Patches currently in -mm which might be from wen.gang.wang@xxxxxxxxxx are