diff options
author | Tim Chase <[email protected]> | 2015-03-31 07:49:15 -0500 |
---|---|---|
committer | Brian Behlendorf <[email protected]> | 2015-04-03 11:32:31 -0700 |
commit | ae26dd003911277e0c7134b3e4e3a41c300a2fd5 (patch) | |
tree | 836cd9f31cbcf68fa091f51921bc23ce247db154 | |
parent | c0899611103c76bb975c7bab5063d937f76e61e6 (diff) |
Don't allow shrinking a PF_FSTRANS context
Avoid deadlocks when entering the shrinker from a PF_FSTRANS context.
This patch also reverts commit d0d5dd7 which added MUTEX_FSTRANS. Its
use has been deprecated within ZFS as it was an ineffective mechanism
to eliminate deadlocks. Among other things, it introduced the need for
strict ordering of mutex locking and unlocking in order that the
PF_FSTRANS flag wouldn't set incorrectly.
Signed-off-by: Tim Chase <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #446
-rw-r--r-- | include/sys/mutex.h | 56 | ||||
-rw-r--r-- | module/spl/spl-kmem-cache.c | 6 |
2 files changed, 27 insertions, 35 deletions
diff --git a/include/sys/mutex.h b/include/sys/mutex.h index 6355782c0..9b297e9fa 100644 --- a/include/sys/mutex.h +++ b/include/sys/mutex.h @@ -32,19 +32,29 @@ typedef enum { MUTEX_DEFAULT = 0, MUTEX_SPIN = 1, - MUTEX_ADAPTIVE = 2, - MUTEX_FSTRANS = 3, + MUTEX_ADAPTIVE = 2 } kmutex_type_t; typedef struct { struct mutex m_mutex; - kmutex_type_t m_type; spinlock_t m_lock; /* used for serializing mutex_exit */ kthread_t *m_owner; - unsigned int m_saved_flags; } kmutex_t; #define MUTEX(mp) (&((mp)->m_mutex)) + +static inline void +spl_mutex_set_owner(kmutex_t *mp) +{ + mp->m_owner = current; +} + +static inline void +spl_mutex_clear_owner(kmutex_t *mp) +{ + mp->m_owner = NULL; +} + #define mutex_owner(mp) (ACCESS_ONCE((mp)->m_owner)) #define mutex_owned(mp) (mutex_owner(mp) == current) #define MUTEX_HELD(mp) mutex_owned(mp) @@ -60,18 +70,11 @@ typedef struct { #define mutex_init(mp, name, type, ibc) \ { \ static struct lock_class_key __key; \ - \ - ASSERT3P(mp, !=, NULL); \ - ASSERT3P(ibc, ==, NULL); \ - ASSERT((type == MUTEX_DEFAULT) || \ - (type == MUTEX_ADAPTIVE) || \ - (type == MUTEX_FSTRANS)); \ + ASSERT(type == MUTEX_DEFAULT); \ \ __mutex_init(MUTEX(mp), (name) ? (#name) : (#mp), &__key); \ spin_lock_init(&(mp)->m_lock); \ - (mp)->m_type = type; \ - (mp)->m_owner = NULL; \ - (mp)->m_saved_flags = 0; \ + spl_mutex_clear_owner(mp); \ } #undef mutex_destroy @@ -84,13 +87,8 @@ typedef struct { ({ \ int _rc_; \ \ - if ((_rc_ = mutex_trylock(MUTEX(mp))) == 1) { \ - (mp)->m_owner = current; \ - if ((mp)->m_type == MUTEX_FSTRANS) { \ - (mp)->m_saved_flags = current->flags; \ - current->flags |= PF_FSTRANS; \ - } \ - } \ + if ((_rc_ = mutex_trylock(MUTEX(mp))) == 1) \ + spl_mutex_set_owner(mp); \ \ _rc_; \ }) @@ -100,22 +98,14 @@ typedef struct { { \ ASSERT3P(mutex_owner(mp), !=, current); \ mutex_lock_nested(MUTEX(mp), (subclass)); \ - (mp)->m_owner = current; \ - if ((mp)->m_type == MUTEX_FSTRANS) { \ - (mp)->m_saved_flags = current->flags; \ - current->flags |= PF_FSTRANS; \ - } \ + spl_mutex_set_owner(mp); \ } #else /* CONFIG_DEBUG_LOCK_ALLOC */ #define mutex_enter_nested(mp, subclass) \ { \ ASSERT3P(mutex_owner(mp), !=, current); \ mutex_lock(MUTEX(mp)); \ - (mp)->m_owner = current; \ - if ((mp)->m_type == MUTEX_FSTRANS) { \ - (mp)->m_saved_flags = current->flags; \ - current->flags |= PF_FSTRANS; \ - } \ + spl_mutex_set_owner(mp); \ } #endif /* CONFIG_DEBUG_LOCK_ALLOC */ @@ -143,11 +133,7 @@ typedef struct { #define mutex_exit(mp) \ { \ spin_lock(&(mp)->m_lock); \ - if ((mp)->m_type == MUTEX_FSTRANS) { \ - current->flags &= ~(PF_FSTRANS); \ - current->flags |= (mp)->m_saved_flags; \ - } \ - (mp)->m_owner = NULL; \ + spl_mutex_clear_owner(mp); \ mutex_unlock(MUTEX(mp)); \ spin_unlock(&(mp)->m_lock); \ } diff --git a/module/spl/spl-kmem-cache.c b/module/spl/spl-kmem-cache.c index 6fcc7c4e1..cd3e543ba 100644 --- a/module/spl/spl-kmem-cache.c +++ b/module/spl/spl-kmem-cache.c @@ -1574,6 +1574,12 @@ __spl_kmem_cache_generic_shrinker(struct shrinker *shrink, spl_kmem_cache_t *skc; int alloc = 0; + /* + * No shrinking in a transaction context. Can cause deadlocks. + */ + if (sc->nr_to_scan && spl_fstrans_check()) + return (SHRINK_STOP); + down_read(&spl_kmem_cache_sem); list_for_each_entry(skc, &spl_kmem_cache_list, skc_list) { if (sc->nr_to_scan) { |