From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> Subject: radix tree test suite: iteration test misuses RCU Each thread needs to register itself with RCU, otherwise the reading thread's read lock has no effect and the freeing thread will free the memory in the tree without waiting for the read lock to be dropped. Link: http://lkml.kernel.org/r/1480369871-5271-42-git-send-email-mawilcox@xxxxxxxxxxxxxxxxx Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> Tested-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: Konstantin Khlebnikov <koct9i@xxxxxxxxx> Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- tools/testing/radix-tree/iteration_check.c | 28 +++++++++++++++++-- 1 file changed, 26 insertions(+), 2 deletions(-) diff -puN tools/testing/radix-tree/iteration_check.c~radix-tree-test-suite-iteration-test-misuses-rcu tools/testing/radix-tree/iteration_check.c --- a/tools/testing/radix-tree/iteration_check.c~radix-tree-test-suite-iteration-test-misuses-rcu +++ a/tools/testing/radix-tree/iteration_check.c @@ -29,6 +29,8 @@ static void *add_entries_fn(void *arg) { int pgoff; + rcu_register_thread(); + while (!test_complete) { for (pgoff = 0; pgoff < 100; pgoff++) { pthread_mutex_lock(&tree_lock); @@ -38,6 +40,8 @@ static void *add_entries_fn(void *arg) } } + rcu_unregister_thread(); + return NULL; } @@ -53,6 +57,8 @@ static void *tagged_iteration_fn(void *a struct radix_tree_iter iter; void **slot; + rcu_register_thread(); + while (!test_complete) { rcu_read_lock(); radix_tree_for_each_tagged(slot, &tree, &iter, 0, TAG) { @@ -72,12 +78,18 @@ static void *tagged_iteration_fn(void *a continue; } - if (rand_r(&seeds[0]) % 50 == 0) + if (rand_r(&seeds[0]) % 50 == 0) { slot = radix_tree_iter_next(&iter); + rcu_read_unlock(); + rcu_barrier(); + rcu_read_lock(); + } } rcu_read_unlock(); } + rcu_unregister_thread(); + return NULL; } @@ -93,6 +105,8 @@ static void *untagged_iteration_fn(void struct radix_tree_iter iter; void **slot; + rcu_register_thread(); + while (!test_complete) { rcu_read_lock(); radix_tree_for_each_slot(slot, &tree, &iter, 0) { @@ -112,12 +126,18 @@ static void *untagged_iteration_fn(void continue; } - if (rand_r(&seeds[1]) % 50 == 0) + if (rand_r(&seeds[1]) % 50 == 0) { slot = radix_tree_iter_next(&iter); + rcu_read_unlock(); + rcu_barrier(); + rcu_read_lock(); + } } rcu_read_unlock(); } + rcu_unregister_thread(); + return NULL; } @@ -127,6 +147,8 @@ static void *untagged_iteration_fn(void */ static void *remove_entries_fn(void *arg) { + rcu_register_thread(); + while (!test_complete) { int pgoff; @@ -137,6 +159,8 @@ static void *remove_entries_fn(void *arg pthread_mutex_unlock(&tree_lock); } + rcu_unregister_thread(); + return NULL; } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
