| Message ID | 20230628010756.70649-1-yukuai1@huaweicloud.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | md/raid5-cache: fix a deadlock in r5l_exit_log() | expand |
Hi, 在 2023/06/28 9:07, Yu Kuai 写道: > From: Yu Kuai <yukuai3@huawei.com> > > Changes in v2: > - remove a now unused local variable in patch 2; > > 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 > > patch 1 revert this patch, an patch 2 fix the original problem in a > different way. > > Noted this problem is just found by code review, and I think this is > probably the reason that some mdadm tests is broken. Any suggestions? By the way, while taking another look at this problem, I think probably read and write 'conf->log' should use READ_ONCE and WRITE_ONCE. Thanks, Kuai > > Yu Kuai (2): > md/raid5-cache: Revert "md/raid5-cache: Clear conf->log after > finishing work" > md/raid5-cache: fix null-ptr-deref in r5l_reclaim_thread() > > drivers/md/raid5-cache.c | 25 ++++++++++--------------- > 1 file changed, 10 insertions(+), 15 deletions(-) >
From: Yu Kuai <yukuai3@huawei.com> Changes in v2: - remove a now unused local variable in patch 2; 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 patch 1 revert this patch, an patch 2 fix the original problem in a different way. Noted this problem is just found by code review, and I think this is probably the reason that some mdadm tests is broken. Yu Kuai (2): md/raid5-cache: Revert "md/raid5-cache: Clear conf->log after finishing work" md/raid5-cache: fix null-ptr-deref in r5l_reclaim_thread() drivers/md/raid5-cache.c | 25 ++++++++++--------------- 1 file changed, 10 insertions(+), 15 deletions(-)