This is a note to let you know that I've just added the patch titled
dm writecache: set a default MAX_WRITEBACK_JOBS
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dm-writecache-set-a-default-max_writeback_jobs.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ca7dc242e358e46d963b32f9d9dd829785a9e957 Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Date: Wed, 13 Jul 2022 07:09:04 -0400
Subject: dm writecache: set a default MAX_WRITEBACK_JOBS
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
commit ca7dc242e358e46d963b32f9d9dd829785a9e957 upstream.
dm-writecache has the capability to limit the number of writeback jobs
in progress. However, this feature was off by default. As such there
were some out-of-memory crashes observed when lowering the low
watermark while the cache is full.
This commit enables writeback limit by default. It is set to 256MiB or
1/16 of total system memory, whichever is smaller.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/dm-writecache.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -20,7 +20,7 @@
#define HIGH_WATERMARK 50
#define LOW_WATERMARK 45
-#define MAX_WRITEBACK_JOBS 0
+#define MAX_WRITEBACK_JOBS min(0x10000000 / PAGE_SIZE, totalram_pages / 16)
#define ENDIO_LATENCY 16
#define WRITEBACK_LATENCY 64
#define AUTOCOMMIT_BLOCKS_SSD 65536
Patches currently in stable-queue which might be from mpatocka@xxxxxxxxxx are
queue-4.19/md-raid10-fix-kasan-warning.patch
queue-4.19/dm-raid-fix-address-sanitizer-warning-in-raid_status.patch
queue-4.19/dm-raid-fix-address-sanitizer-warning-in-raid_resume.patch
queue-4.19/add-barriers-to-buffer_uptodate-and-set_buffer_uptodate.patch
queue-4.19/dm-writecache-set-a-default-max_writeback_jobs.patch
