diff options
| author | Brian Behlendorf <[email protected]> | 2013-04-25 16:29:22 -0700 |
|---|---|---|
| committer | Brian Behlendorf <[email protected]> | 2013-04-26 14:42:36 -0700 |
| commit | 57f5a2008e2e6acf58934cf43c5fdca0faffa73e (patch) | |
| tree | 6097764cffc614760d918d844479d85414c84075 /module/zfs/dsl_pool.c | |
| parent | 0c15bf16f1050e710cad1783d15eea63cca792c0 (diff) | |
Fix txg_quiesce thread deadlock
A deadlock was accidentally introduced by commit e95853a which
can occur when the system is under memory pressure. What happens
is that while the txg_quiesce thread is holding the tx->tx_cpu
locks it enters memory reclaim. In the context of this memory
reclaim it then issues synchronous I/O to a ZVOL swap device.
Because the txg_quiesce thread is holding the tx->tx_cpu locks
a new txg cannot be opened to handle the I/O. Deadlock.
The fix is straight forward. Move the memory allocation outside
the critical region where the tx->tx_cpu locks are held. And for
good measure change the offending allocation to KM_PUSHPAGE to
ensure it never attempts to issue I/O during reclaim.
Signed-off-by: Brian Behlendorf <[email protected]>
Issue #1274
Diffstat (limited to 'module/zfs/dsl_pool.c')
| -rw-r--r-- | module/zfs/dsl_pool.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/module/zfs/dsl_pool.c b/module/zfs/dsl_pool.c index 704f034e9..771b265c2 100644 --- a/module/zfs/dsl_pool.c +++ b/module/zfs/dsl_pool.c @@ -143,7 +143,7 @@ dsl_pool_txg_history_add(dsl_pool_t *dp, uint64_t txg) { txg_history_t *th, *rm; - th = kmem_zalloc(sizeof(txg_history_t), KM_SLEEP); + th = kmem_zalloc(sizeof(txg_history_t), KM_PUSHPAGE); mutex_init(&th->th_lock, NULL, MUTEX_DEFAULT, NULL); th->th_kstat.txg = txg; th->th_kstat.state = TXG_STATE_OPEN; |