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Date:   Sat, 2 Dec 2017 15:52:19 +0000
To:     "" <>,
        "" <>
Cc:     "Darrick J. Wong" <>,
        Omar Sandoval <>,
Subject: [PATCH AUTOSEL for 4.9 14/33] xfs: fix forgotten rcu read unlock when
 skipping inode reclaim

From: "Darrick J. Wong" <>

[ Upstream commit 962cc1ad6caddb5abbb9f0a43e5abe7131a71f18 ]

In commit f2e9ad21 ("xfs: check for race with xfs_reclaim_inode"), we
skip an inode if we're racing with freeing the inode via
xfs_reclaim_inode, but we forgot to release the rcu read lock when
dumping the inode, with the result that we exit to userspace with a lock
held.  Don't do that; generic/320 with a 1k block size fails this
very occasionally.

WARNING: lock held when returning to user space!
4.14.0-rc6-djwong #4 Tainted: G        W
rm/30466 is leaving the kernel with locks still held!
1 lock held by rm/30466:
 #0:  (rcu_read_lock){....}, at: [<ffffffffa01364d3>] xfs_ifree_cluster.isra.17+0x2c3/0x6f0 [xfs]
------------[ cut here ]------------
WARNING: CPU: 1 PID: 30466 at kernel/rcu/tree_plugin.h:329 rcu_note_context_switch+0x71/0x700
Modules linked in: deadline_iosched dm_snapshot dm_bufio ext4 mbcache jbd2 dm_flakey xfs libcrc32c dax_pmem device_dax nd_pmem sch_fq_codel af_packet [last unloaded: scsi_debug]
CPU: 1 PID: 30466 Comm: rm Tainted: G        W       4.14.0-rc6-djwong #4
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-1ubuntu1djwong0 04/01/2014
task: ffff880037680000 task.stack: ffffc90001064000
RIP: 0010:rcu_note_context_switch+0x71/0x700
RSP: 0000:ffffc90001067e50 EFLAGS: 00010002
RAX: 0000000000000001 RBX: ffff880037680000 RCX: ffff88003e73d200
RDX: 0000000000000002 RSI: ffffffff819e53e9 RDI: ffffffff819f4375
RBP: 0000000000000000 R08: 0000000000000000 R09: ffff880062c900d0
R10: 0000000000000000 R11: 0000000000000000 R12: ffff880037680000
R13: 0000000000000000 R14: ffffc90001067eb8 R15: ffff880037680690
FS:  00007fa3b8ce8700(0000) GS:ffff88003ec00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f69bf77c000 CR3: 000000002450a000 CR4: 00000000000006e0
Call Trace:
RIP: 0033:0x7fa3b87fda87
RSP: 002b:00007ffe41206568 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff02
RAX: 0000000000000000 RBX: 00000000010e88c0 RCX: 00007fa3b87fda87
RDX: 0000000000000000 RSI: 00000000010e89c8 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000000
R10: 000000000000015e R11: 0000000000000246 R12: 00000000010c8060
R13: 00007ffe41206690 R14: 0000000000000000 R15: 0000000000000000
---[ end trace e88f83bf0cfbd07d ]---

Fixes: f2e9ad212def50bcf4c098c6288779dd97fff0f0
Cc: Omar Sandoval <>
Signed-off-by: Darrick J. Wong <>
Reviewed-by: Christoph Hellwig <>
Reviewed-by: Omar Sandoval <>
Signed-off-by: Sasha Levin <>
 fs/xfs/xfs_inode.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index fe9a9a183b2d..98ca9f1b6a07 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -2386,6 +2386,7 @@ retry:
 				if (ip->i_ino != inum + i) {
 					xfs_iunlock(ip, XFS_ILOCK_EXCL);
+					rcu_read_unlock();

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