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authorDan Williams <dan.j.williams@intel.com>2020-09-18 12:51:15 -0700
committerDan Williams <dan.j.williams@intel.com>2020-09-20 08:33:56 -0700
commit02186d8897d49b0afd3c80b6cf23437d91024065 (patch)
treef715793734ad13cc07e8c5159668a2164f8244fc
parent856deb866d16e29bd65952e0289066f6078af773 (diff)
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dm/dax: Fix table reference counts
A recent fix to the dm_dax_supported() flow uncovered a latent bug. When dm_get_live_table() fails it is still required to drop the srcu_read_lock(). Without this change the lvm2 test-suite triggers this warning: # lvm2-testsuite --only pvmove-abort-all.sh WARNING: lock held when returning to user space! 5.9.0-rc5+ #251 Tainted: G OE ------------------------------------------------ lvm/1318 is leaving the kernel with locks still held! 1 lock held by lvm/1318: #0: ffff9372abb5a340 (&md->io_barrier){....}-{0:0}, at: dm_get_live_table+0x5/0xb0 [dm_mod] ...and later on this hang signature: INFO: task lvm:1344 blocked for more than 122 seconds. Tainted: G OE 5.9.0-rc5+ #251 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:lvm state:D stack: 0 pid: 1344 ppid: 1 flags:0x00004000 Call Trace: __schedule+0x45f/0xa80 ? finish_task_switch+0x249/0x2c0 ? wait_for_completion+0x86/0x110 schedule+0x5f/0xd0 schedule_timeout+0x212/0x2a0 ? __schedule+0x467/0xa80 ? wait_for_completion+0x86/0x110 wait_for_completion+0xb0/0x110 __synchronize_srcu+0xd1/0x160 ? __bpf_trace_rcu_utilization+0x10/0x10 __dm_suspend+0x6d/0x210 [dm_mod] dm_suspend+0xf6/0x140 [dm_mod] Fixes: 7bf7eac8d648 ("dax: Arrange for dax_supported check to span multiple devices") Cc: <stable@vger.kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Alasdair Kergon <agk@redhat.com> Cc: Mike Snitzer <snitzer@redhat.com> Reported-by: Adrian Huang <ahuang12@lenovo.com> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Tested-by: Adrian Huang <ahuang12@lenovo.com> Link: https://lore.kernel.org/r/160045867590.25663.7548541079217827340.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com>
-rw-r--r--drivers/md/dm.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index fb0255d25e4b..4a40df8af7d3 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1136,15 +1136,16 @@ static bool dm_dax_supported(struct dax_device *dax_dev, struct block_device *bd
{
struct mapped_device *md = dax_get_private(dax_dev);
struct dm_table *map;
+ bool ret = false;
int srcu_idx;
- bool ret;
map = dm_get_live_table(md, &srcu_idx);
if (!map)
- return false;
+ goto out;
ret = dm_table_supports_dax(map, device_supports_dax, &blocksize);
+out:
dm_put_live_table(md, srcu_idx);
return ret;