Disable direct reclaim in taskq worker threads on Linux 3.9+

Illumos does not have direct reclaim and code run inside taskq worker threads is not designed to deal with it. Allowing direct reclaim inside a worker thread can therefore deadlock. We set PF_MEMALLOC_NOIO through memalloc_noio_save() to indicate to the kernel's reclaim code that we are inside a context where memory allocations cannot be allowed to block on filesystem activity. Signed-off-by: Richard Yao <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Issue openzfs#1274 Issue openzfs#2390 Closes openzfs#474
behlendorf · Sep 9, 2015 · d4bf6d8 · d4bf6d8
1 parent 4fa4cab
commit d4bf6d8
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/module/spl/spl-taskq.c b/module/spl/spl-taskq.c
@@ -817,6 +817,10 @@ taskq_thread(void *args)
 	tq = tqt->tqt_tq;
 	current->flags |= PF_NOFREEZE;
 
+	#if defined(PF_MEMALLOC_NOIO)
+	(void) memalloc_noio_save();
+	#endif
+
 	sigfillset(&blocked);
 	sigprocmask(SIG_BLOCK, &blocked, NULL);
 	flush_signals(current);