The patch titled
Subject: mm: bdi: initialize bdi_min_ratio when bdi is unregistered
has been added to the -mm tree. Its filename is
mm-bdi-initialize-bdi_min_ratio-when-bdi-unregister.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-bdi-initialize-bdi_min_ratio-when-bdi-unregister.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-bdi-initialize-bdi_min_ratio-when-bdi-unregister.patch
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------------------------------------------------------
From: Manjong Lee <mj0123.lee@xxxxxxxxxxx>
Subject: mm: bdi: initialize bdi_min_ratio when bdi is unregistered
Initialize min_ratio if it is set during bdi unregistration.
This can prevent problems that may occur a when bdi is removed without
resetting min_ratio.
For example.
1) insert external sdcard
2) set external sdcard's min_ratio 70
3) remove external sdcard without setting min_ratio 0
4) insert external sdcard
5) set external sdcard's min_ratio 70 << error occur(can't set)
Because when an sdcard is removed, the present bdi_min_ratio value will
remain. Currently, the only way to reset bdi_min_ratio is to reboot.
Link: https://lkml.kernel.org/r/20211021161942.5983-1-mj0123.lee@xxxxxxxxxxx
Signed-off-by: Manjong Lee <mj0123.lee@xxxxxxxxxxx>
Cc: Changheun Lee <nanich.lee@xxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: <seunghwan.hyun@xxxxxxxxxxx>
Cc: <sookwan7.kim@xxxxxxxxxxx>
Cc: <yt0928.kim@xxxxxxxxxxx>
Cc: <junho89.kim@xxxxxxxxxxx>
Cc: <jisoo2146.oh@xxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/backing-dev.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/mm/backing-dev.c~mm-bdi-initialize-bdi_min_ratio-when-bdi-unregister
+++ a/mm/backing-dev.c
@@ -947,6 +947,11 @@ void bdi_unregister(struct backing_dev_i
wb_shutdown(&bdi->wb);
cgwb_bdi_unregister(bdi);
+ /* if min ratio doesn't 0, it has to set 0 before unregister */
+ if (bdi->min_ratio) {
+ bdi_set_min_ratio(bdi, 0);
+ }
+
if (bdi->dev) {
bdi_debug_unregister(bdi);
device_unregister(bdi->dev);
_
Patches currently in -mm which might be from mj0123.lee@xxxxxxxxxxx are
mm-bdi-initialize-bdi_min_ratio-when-bdi-unregister.patch
