On Sun, 1 Feb 2015 21:08:12 -0800 Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > On Sun, Feb 1, 2015 at 3:03 PM, NeilBrown <neilb@xxxxxxx> wrote: > > > > I guess I could > > __set_current_state(TASK_RUNNING); > > somewhere to defeat the warning, and add a comment explaining why. > > > > Would that be a good thing? > > Use "sched_annotate_sleep()" instead, but yes, add a comment about why it's ok. > > Linus > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ OK - following patch is queued to appear in a pull request tomorrow (I hope). Thanks, NeilBrown From: NeilBrown <neilb@xxxxxxx> Date: Mon, 2 Feb 2015 17:08:03 +1100 Subject: [PATCH] md/bitmap: fix a might_sleep() warning. commit 8eb23b9f35aae413140d3fda766a98092c21e9b0 sched: Debug nested sleeps causes false-positive warnings in RAID5 code. This annotation removes them and adds a comment explaining why there is no real problem. Reported-by: Fengguang Wu <fengguang.wu@xxxxxxxxx> Signed-off-by: NeilBrown <neilb@xxxxxxx> diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c index da3604e73e8a..1695ee5f3ffc 100644 --- a/drivers/md/bitmap.c +++ b/drivers/md/bitmap.c @@ -72,6 +72,19 @@ __acquires(bitmap->lock) /* this page has not been allocated yet */ spin_unlock_irq(&bitmap->lock); + /* It is possible that this is being called inside a + * prepare_to_wait/finish_wait loop from raid5c:make_request(). + * In general it is not permitted to sleep in that context as it + * can cause the loop to spin freely. + * That doesn't apply here as we can only reach this point + * once with any loop. + * When this function completes, either bp[page].map or + * bp[page].hijacked. In either case, this function will + * abort before getting to this point again. So there is + * no risk of a free-spin, and so it is safe to assert + * that sleeping here is allowed. + */ + sched_annotate_sleep(); mappage = kzalloc(PAGE_SIZE, GFP_NOIO); spin_lock_irq(&bitmap->lock);
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