When CONFIG_PROVE_RCU=y and CONFIG_PROVE_RCU_REPEATEDLY=y, the
following was dumped in dmesg:
[ 3197.218064] ===============================
[ 3197.218064] [ INFO: suspicious RCU usage. ]
[ 3197.218066] 3.15.0-rc8-fdm-btrfs-next-33+ #4 Not tainted
[ 3197.218067] -------------------------------
[ 3197.218068] include/linux/radix-tree.h:196 suspicious rcu_dereference_check() usage!
[ 3197.218068]
[ 3197.218068] other info that might help us debug this:
[ 3197.218068]
[ 3197.218070]
[ 3197.218070] rcu_scheduler_active = 1, debug_locks = 1
[ 3197.218071] 1 lock held by modprobe/12024:
[ 3197.218072] #0: (&(&fs_info->buffer_lock)->rlock){+.+...}, at: [<ffffffffa025c5fa>] btrfs_free_dummy_root+0x5a/0x1d0 [btrfs]
[ 3197.218093]
[ 3197.218093] stack backtrace:
[ 3197.218095] CPU: 3 PID: 12024 Comm: modprobe Not tainted 3.15.0-rc8-fdm-btrfs-next-33+ #4
[ 3197.218096] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 3197.218097] 0000000000000001 ffff8800af18fc18 ffffffff81685c5a 000000000000feb0
[ 3197.218099] ffff8800cf6ccb40 ffff8800af18fc48 ffffffff810a6316 ffff8801d955f640
[ 3197.218101] ffff8800d719e328 ffff8800d719e370 ffff8800d719c000 ffff8800af18fcb8
[ 3197.218102] Call Trace:
[ 3197.218105] [<ffffffff81685c5a>] dump_stack+0x4e/0x68
[ 3197.218108] [<ffffffff810a6316>] lockdep_rcu_suspicious+0xe6/0x130
[ 3197.218119] [<ffffffffa025c728>] btrfs_free_dummy_root+0x188/0x1d0 [btrfs]
[ 3197.218129] [<ffffffffa025f56a>] btrfs_test_qgroups+0xea/0x1bb [btrfs]
[ 3197.218137] [<ffffffffa03a19d2>] ? ftrace_define_fields_btrfs_space_reservation+0xfd/0xfd [btrfs]
[ 3197.218144] [<ffffffffa03a19d2>] ? ftrace_define_fields_btrfs_space_reservation+0xfd/0xfd [btrfs]
[ 3197.218151] [<ffffffffa03a1ab7>] init_btrfs_fs+0xe5/0x184 [btrfs]
[ 3197.218154] [<ffffffff81000352>] do_one_initcall+0x102/0x150
[ 3197.218157] [<ffffffff8103d223>] ? set_memory_nx+0x43/0x50
[ 3197.218160] [<ffffffff81682668>] ? set_section_ro_nx+0x6d/0x74
[ 3197.218162] [<ffffffff810d91cc>] load_module+0x1cdc/0x2630
[ 3197.218164] [<ffffffff810d4e90>] ? show_initstate+0x60/0x60
[ 3197.218166] [<ffffffff810d9c9e>] SyS_finit_module+0x8e/0x90
[ 3197.218168] [<ffffffff81698212>] system_call_fastpath+0x16/0x1b
Signed-off-by: Filipe David Borba Manana <fdmanana@xxxxxxxxx>
---
V2: Added missing rcu read unlock if a retry is needed.
fs/btrfs/tests/btrfs-tests.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/tests/btrfs-tests.c b/fs/btrfs/tests/btrfs-tests.c
index a5dcacb..bdb1f05 100644
--- a/fs/btrfs/tests/btrfs-tests.c
+++ b/fs/btrfs/tests/btrfs-tests.c
@@ -130,8 +130,8 @@ static void btrfs_free_dummy_fs_info(struct btrfs_fs_info *fs_info)
struct radix_tree_iter iter;
void **slot;
- spin_lock(&fs_info->buffer_lock);
restart:
+ rcu_read_lock();
radix_tree_for_each_slot(slot, &fs_info->buffer_radix, &iter, 0) {
struct extent_buffer *eb;
@@ -140,15 +140,17 @@ restart:
continue;
/* Shouldn't happen but that kind of thinking creates CVE's */
if (radix_tree_exception(eb)) {
- if (radix_tree_deref_retry(eb))
+ if (radix_tree_deref_retry(eb)) {
+ rcu_read_unlock();
goto restart;
+ }
continue;
}
- spin_unlock(&fs_info->buffer_lock);
+ rcu_read_unlock();
free_extent_buffer_stale(eb);
- spin_lock(&fs_info->buffer_lock);
+ goto restart;
}
- spin_unlock(&fs_info->buffer_lock);
+ rcu_read_unlock();
btrfs_free_qgroup_config(fs_info);
btrfs_free_fs_roots(fs_info);
--
1.9.1
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
