linux-kernel - [PATCH 4.9 126/157] fuse: fix live lock in fuse

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Date:   Mon, 24 Jan 2022 19:43:36 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Amir Goldstein <amir73il@...il.com>,
        Miklos Szeredi <mszeredi@...hat.com>,
        Ben Hutchings <ben@...adent.org.uk>
Subject: [PATCH 4.9 126/157] fuse: fix live lock in fuse_iget()

From: Amir Goldstein <amir73il@...il.com>

commit 775c5033a0d164622d9d10dd0f0a5531639ed3ed upstream.

Commit 5d069dbe8aaf ("fuse: fix bad inode") replaced make_bad_inode()
in fuse_iget() with a private implementation fuse_make_bad().

The private implementation fails to remove the bad inode from inode
cache, so the retry loop with iget5_locked() finds the same bad inode
and marks it bad forever.

kmsg snip:

[ ] rcu: INFO: rcu_sched self-detected stall on CPU
...
[ ]  ? bit_wait_io+0x50/0x50
[ ]  ? fuse_init_file_inode+0x70/0x70
[ ]  ? find_inode.isra.32+0x60/0xb0
[ ]  ? fuse_init_file_inode+0x70/0x70
[ ]  ilookup5_nowait+0x65/0x90
[ ]  ? fuse_init_file_inode+0x70/0x70
[ ]  ilookup5.part.36+0x2e/0x80
[ ]  ? fuse_init_file_inode+0x70/0x70
[ ]  ? fuse_inode_eq+0x20/0x20
[ ]  iget5_locked+0x21/0x80
[ ]  ? fuse_inode_eq+0x20/0x20
[ ]  fuse_iget+0x96/0x1b0

Fixes: 5d069dbe8aaf ("fuse: fix bad inode")
Cc: stable@...r.kernel.org # 5.10+
Signed-off-by: Amir Goldstein <amir73il@...il.com>
Signed-off-by: Miklos Szeredi <mszeredi@...hat.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/fuse/fuse_i.h |    1 +
 1 file changed, 1 insertion(+)

--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -692,6 +692,7 @@ static inline u64 get_node_id(struct ino
 
 static inline void fuse_make_bad(struct inode *inode)
 {
+	remove_inode_hash(inode);
 	set_bit(FUSE_I_BAD, &get_fuse_inode(inode)->state);
 }