On Thu, 9 May 2019, Jens Axboe wrote:
> On 5/9/19 10:54 AM, Mikulas Patocka wrote:
> > The loop that frees all the pages can take unbounded amount of time, so
> > add cond_resched() to it.
>
> Looks fine to me, would be nice with a comment on why the cond_resched()
> is needed though.
>
> --
> Jens Axboe
OK - here I added the comment.
Mikulas
From: Mikulas Patocka <[email protected]>
Subject: [PATCH] brd: add cond_resched to brd_free_pages
The loop that frees all the pages can take unbounded amount of time, so
add cond_resched() to it.
Signed-off-by: Mikulas Patocka <[email protected]>
---
drivers/block/brd.c | 6 ++++++
1 file changed, 6 insertions(+)
Index: linux-2.6/drivers/block/brd.c
===================================================================
--- linux-2.6.orig/drivers/block/brd.c 2019-05-09 20:46:23.000000000 +0200
+++ linux-2.6/drivers/block/brd.c 2019-05-09 20:47:43.000000000 +0200
@@ -158,6 +158,12 @@ static void brd_free_pages(struct brd_de
pos++;
/*
+ * It takes 3.4 seconds to remove 80GiB ramdisk.
+ * So, we need cond_resched to avoid stalling the CPU.
+ */
+ cond_resched();
+
+ /*
* This assumes radix_tree_gang_lookup always returns as
* many pages as possible. If the radix-tree code changes,
* so will this have to.
