aio: annotate aio_read_event_ring for sleep patterns

Dave Chinner · bcrl · commit 9c9ce763b114 · 2015-02-03T19:29:05.000-05:00
Under CONFIG_DEBUG_ATOMIC_SLEEP=y, aio_read_event_ring() will throw warnings like the following due to being called from wait_event context: WARNING: CPU: 0 PID: 16006 at kernel/sched/core.c:7300 __might_sleep+0x7f/0x90() do not call blocking ops when !TASK_RUNNING; state=1 set at [<ffffffff810d85a3>] prepare_to_wait_event+0x63/0x110 Modules linked in: CPU: 0 PID: 16006 Comm: aio-dio-fcntl-r Not tainted 3.19.0-rc6-dgc+ torvalds#705 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 ffffffff821c0372 ffff88003c117cd8 ffffffff81daf2bd 000000000000d8d8 ffff88003c117d28 ffff88003c117d18 ffffffff8109beda ffff88003c117cf8 ffffffff821c115e 0000000000000061 0000000000000000 00007ffffe4aa300 Call Trace: [<ffffffff81daf2bd>] dump_stack+0x4c/0x65 [<ffffffff8109beda>] warn_slowpath_common+0x8a/0xc0 [<ffffffff8109bf56>] warn_slowpath_fmt+0x46/0x50 [<ffffffff810d85a3>] ? prepare_to_wait_event+0x63/0x110 [<ffffffff810d85a3>] ? prepare_to_wait_event+0x63/0x110 [<ffffffff810bdfcf>] __might_sleep+0x7f/0x90 [<ffffffff81db8344>] mutex_lock+0x24/0x45 [<ffffffff81216b7c>] aio_read_events+0x4c/0x290 [<ffffffff81216fac>] read_events+0x1ec/0x220 [<ffffffff810d8650>] ? prepare_to_wait_event+0x110/0x110 [<ffffffff810fdb10>] ? hrtimer_get_res+0x50/0x50 [<ffffffff8121899d>] SyS_io_getevents+0x4d/0xb0 [<ffffffff81dba5a9>] system_call_fastpath+0x12/0x17 ---[ end trace bde69eaf655a4fea ]--- There is not actually a bug here, so annotate the code to tell the debug logic that everything is just fine and not to fire a false positive. Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
diff --git a/fs/aio.c b/fs/aio.c
@@ -1140,6 +1140,13 @@ static long aio_read_events_ring(struct kioctx *ctx,
 	long ret = 0;
 	int copy_ret;
 
+	/*
+	 * The mutex can block and wake us up and that will cause
+	 * wait_event_interruptible_hrtimeout() to schedule without sleeping
+	 * and repeat. This should be rare enough that it doesn't cause
+	 * peformance issues. See the comment in read_events() for more detail.
+	 */
+	sched_annotate_sleep();
 	mutex_lock(&ctx->ring_lock);
 
 	/* Access to ->ring_pages here is protected by ctx->ring_lock. */
