From: Manjong Lee <mj0123.lee@samsung.com> stable inclusion from linux-4.19.221 commit 505039dd0fe6493565e27b55700e46f43f20580d -------------------------------- commit 3c376dfafbf7a8ea0dea212d095ddd83e93280bb upstream. 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. [akpm@linux-foundation.org: tweak comment and coding style] Link: https://lkml.kernel.org/r/20211021161942.5983-1-mj0123.lee@samsung.com Signed-off-by: Manjong Lee <mj0123.lee@samsung.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Changheun Lee <nanich.lee@samsung.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: <seunghwan.hyun@samsung.com> Cc: <sookwan7.kim@samsung.com> Cc: <yt0928.kim@samsung.com> Cc: <junho89.kim@samsung.com> Cc: <jisoo2146.oh@samsung.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Conflicts: mm/backing-dev.c [yyl: adjust context] Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- mm/backing-dev.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 75a61176f392f..f80d5c2ff420c 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -978,6 +978,13 @@ void bdi_unregister(struct backing_dev_info *bdi) wb_shutdown(&bdi->wb); cgwb_bdi_unregister(bdi); + /* + * If this BDI's min ratio has been set, use bdi_set_min_ratio() to + * update the global bdi_min_ratio. + */ + if (bdi->min_ratio) + bdi_set_min_ratio(bdi, 0); + if (bdi->dev) { struct rcu_device *rcu_dev = bdi->rcu_dev; bdi_debug_unregister(bdi); -- 2.25.1