6.4-stable review patch. If anyone has any objections, please let me know.
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From: Yu Kuai yukuai3@huawei.com
[ Upstream commit a705b11b358dee677aad80630e7608b2d5f56691 ]
Commit b13015af94cf ("md/raid5-cache: Clear conf->log after finishing work") introduce a new problem:
// caller hold reconfig_mutex r5l_exit_log flush_work(&log->disable_writeback_work) r5c_disable_writeback_async wait_event /* * conf->log is not NULL, and mddev_trylock() * will fail, wait_event() can never pass. */ conf->log = NULL
Fix this problem by setting 'config->log' to NULL before wake_up() as it used to be, so that wait_event() from r5c_disable_writeback_async() can exist. In the meantime, move forward md_unregister_thread() so that null-ptr-deref this commit fixed can still be fixed.
Fixes: b13015af94cf ("md/raid5-cache: Clear conf->log after finishing work") Signed-off-by: Yu Kuai yukuai3@huawei.com Link: https://lore.kernel.org/r/20230708091727.1417894-1-yukuai1@huaweicloud.com Signed-off-by: Song Liu song@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/md/raid5-cache.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c index 46182b955aef8..5c246b2697e0b 100644 --- a/drivers/md/raid5-cache.c +++ b/drivers/md/raid5-cache.c @@ -3164,12 +3164,15 @@ void r5l_exit_log(struct r5conf *conf) { struct r5l_log *log = conf->log;
- /* Ensure disable_writeback_work wakes up and exits */ - wake_up(&conf->mddev->sb_wait); - flush_work(&log->disable_writeback_work); md_unregister_thread(&log->reclaim_thread);
+ /* + * 'reconfig_mutex' is held by caller, set 'confg->log' to NULL to + * ensure disable_writeback_work wakes up and exits. + */ conf->log = NULL; + wake_up(&conf->mddev->sb_wait); + flush_work(&log->disable_writeback_work);
mempool_exit(&log->meta_pool); bioset_exit(&log->bs);