diff options
Diffstat (limited to 'mm/zsmalloc.c')
| -rw-r--r-- | mm/zsmalloc.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index 9f15bdd9163c..2d7c4c11fc63 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -213,10 +213,10 @@ struct size_class { int size; unsigned int index; - /* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */ - int pages_per_zspage; struct zs_size_stat stats; + /* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */ + int pages_per_zspage; /* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */ bool huge; }; @@ -309,7 +309,12 @@ static void free_handle(struct zs_pool *pool, unsigned long handle) static void record_obj(unsigned long handle, unsigned long obj) { - *(unsigned long *)handle = obj; + /* + * lsb of @obj represents handle lock while other bits + * represent object value the handle is pointing so + * updating shouldn't do store tearing. + */ + WRITE_ONCE(*(unsigned long *)handle, obj); } /* zpool driver */ @@ -1635,6 +1640,13 @@ static int migrate_zspage(struct zs_pool *pool, struct size_class *class, free_obj = obj_malloc(d_page, class, handle); zs_object_copy(free_obj, used_obj, class); index++; + /* + * record_obj updates handle's value to free_obj and it will + * invalidate lock bit(ie, HANDLE_PIN_BIT) of handle, which + * breaks synchronization using pin_tag(e,g, zs_free) so + * let's keep the lock bit. + */ + free_obj |= BIT(HANDLE_PIN_BIT); record_obj(handle, free_obj); unpin_tag(handle); obj_free(pool, class, used_obj); |