This reverts commit 299772fab304ab3a36b22b5d28ed81f9408972e7
Sasha reported this:
[ 313.262599] ======================================================
[ 313.271340] [ INFO: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected ]
[ 313.277542] 3.8.0-rc6-next-20130208-sasha-00028-ge4e162d #278 Tainted: G
W
[ 313.277542] ------------------------------------------------------
[ 313.277542] kworker/u:3/4490 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
[ 313.277542] (rename_lock){+.+...}, at: [<ffffffff812a11f9>]
dentry_path_raw+0x29/0x70
[ 313.277542]
[ 313.277542] and this task is already holding:
[ 313.277542] (&(&q->__queue_lock)->rlock){-.-...}, at: [<ffffffff819e78f3>]
put_io_context_active+0x63/0x100
[ 313.277542] which would create a new lock dependency:
[ 313.277542] (&(&q->__queue_lock)->rlock){-.-...} -> (rename_lock){+.+...}
[ 313.277542]
[ 313.277542] but this new dependency connects a HARDIRQ-irq-safe lock:
[ 313.277542] (&(&q->__queue_lock)->rlock){-.-...}
dentry_path_raw() grabs rename_lock and dentry->d_lock without disabling
irqs, which means cgroup_path() can't be called if the caller has already
held a spinlock with irq disabled.
Reported-by: Sasha Levin <levinsasha...@gmail.com>
Signed-off-by: Li Zefan <lize...@huawei.com>
---
kernel/cgroup.c | 22 +++++++++++++++++++---
1 file changed, 19 insertions(+), 3 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 776ff75..5d4c92e 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1792,10 +1792,26 @@ int cgroup_path(const struct cgroup *cgrp, char *buf,
int buflen)
return 0;
}
- start = dentry_path_raw(dentry, buf, buflen);
- if (IS_ERR(start))
- return PTR_ERR(start);
+ start = buf + buflen - 1;
+ *start = '\0';
+ for (;;) {
+ int len = dentry->d_name.len;
+
+ if ((start -= len) < buf)
+ return -ENAMETOOLONG;
+ memcpy(start, dentry->d_name.name, len);
+ cgrp = cgrp->parent;
+ if (!cgrp)
+ break;
+
+ dentry = cgrp->dentry;
+ if (!cgrp->parent)
+ continue;
+ if (--start < buf)
+ return -ENAMETOOLONG;
+ *start = '/';
+ }
memmove(buf, start, buf + buflen - start);
return 0;
}
--
1.8.0.2
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