This is a note to let you know that I've just added the patch titled md: Fix missing unused status line of /proc/mdstat to the 5.12-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: md-fix-missing-unused-status-line-of-proc-mdstat.patch and it can be found in the queue-5.12 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 7abfabaf5f805f5171d133ce6af9b65ab766e76a Mon Sep 17 00:00:00 2001 From: Jan Glauber <jglauber@xxxxxxxxxxxxxxxx> Date: Wed, 17 Mar 2021 15:04:39 +0100 Subject: md: Fix missing unused status line of /proc/mdstat From: Jan Glauber <jglauber@xxxxxxxxxxxxxxxx> commit 7abfabaf5f805f5171d133ce6af9b65ab766e76a upstream. Reading /proc/mdstat with a read buffer size that would not fit the unused status line in the first read will skip this line from the output. So 'dd if=/proc/mdstat bs=64 2>/dev/null' will not print something like: unused devices: <none> Don't return NULL immediately in start() for v=2 but call show() once to print the status line also for multiple reads. Cc: stable@xxxxxxxxxxxxxxx Fixes: 1f4aace60b0e ("fs/seq_file.c: simplify seq_file iteration code and interface") Signed-off-by: Jan Glauber <jglauber@xxxxxxxxxxxxxxxx> Signed-off-by: Song Liu <songliubraving@xxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/md/md.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -8172,7 +8172,11 @@ static void *md_seq_start(struct seq_fil loff_t l = *pos; struct mddev *mddev; - if (l >= 0x10000) + if (l == 0x10000) { + ++*pos; + return (void *)2; + } + if (l > 0x10000) return NULL; if (!l--) /* header */ Patches currently in stable-queue which might be from jglauber@xxxxxxxxxxxxxxxx are queue-5.12/md-fix-missing-unused-status-line-of-proc-mdstat.patch