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Chunwei Chen
07012da668
The following panic would occur under certain heavy load: [ 4692.202686] Kernel panic - not syncing: thread ffff8800c4f5dd60 terminating with rrw lock ffff8800da1b9c40 held [ 4692.228053] CPU: 1 PID: 6250 Comm: mmap_deadlock Tainted: P OE 3.18.10 #7 The culprit is that ZFS_EXIT(zsb) would call tsd_exit() every time, which would purge all tsd data for the thread. However, ZFS_ENTER is designed to be reentrant, so we cannot allow ZFS_EXIT to blindly purge tsd data. Instead, we rely on the new behavior of tsd_set. When NULL is passed as the new value to tsd_set, it will automatically remove the tsd entry specified the the key for the current thread. rrw_tsd_key and zfs_allow_log_key already calls tsd_set(key, NULL) when they're done. The zfs_fsyncer_key relied on ZFS_EXIT(zsb) to call tsd_exit() to do clean up. Now we explicitly call tsd_set(key, NULL) on them. Signed-off-by: Chunwei Chen <tuxoko@gmail.com> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #3247