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From:   Stefan Roesch <shr@fb.com>
To:     <io-uring@vger.kernel.org>, <kernel-team@fb.com>,
        <linux-mm@kvack.org>, <linux-xfs@vger.kernel.org>,
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CC:     <shr@fb.com>, <david@fromorbit.com>, <jack@suse.cz>,
        <hch@infradead.org>
Subject: [PATCH v6 02/16] mm: Move updates of dirty_exceeded into one place
Date:   Thu, 26 May 2022 10:38:26 -0700
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From: Jan Kara <jack@suse.cz>

Transition of wb->dirty_exceeded from 0 to 1 happens before we go to
sleep in balance_dirty_pages() while transition from 1 to 0 happens when
exiting from balance_dirty_pages(), possibly based on old values. This
does not make a lot of sense since wb->dirty_exceeded should simply
reflect whether wb is over dirty limit and so we should ratelimit
entering to balance_dirty_pages() less. Move the two updates together.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Stefan Roesch <shr@fb.com>
---
 mm/page-writeback.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 8e5e003f0093..89dcc7d8395a 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1720,8 +1720,8 @@ static void balance_dirty_pages(struct bdi_writebac=
k *wb,
 				sdtc =3D mdtc;
 		}
=20
-		if (dirty_exceeded && !wb->dirty_exceeded)
-			wb->dirty_exceeded =3D 1;
+		if (dirty_exceeded !=3D wb->dirty_exceeded)
+			wb->dirty_exceeded =3D dirty_exceeded;
=20
 		if (time_is_before_jiffies(READ_ONCE(wb->bw_time_stamp) +
 					   BANDWIDTH_INTERVAL))
@@ -1825,9 +1825,6 @@ static void balance_dirty_pages(struct bdi_writebac=
k *wb,
 		if (fatal_signal_pending(current))
 			break;
 	}
-
-	if (!dirty_exceeded && wb->dirty_exceeded)
-		wb->dirty_exceeded =3D 0;
 }
=20
 static DEFINE_PER_CPU(int, bdp_ratelimits);
--=20
2.30.2