This is a note to let you know that I've just added the patch titled
md: split mddev_find
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-split-mddev_find.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 65aa97c4d2bfd76677c211b9d03ef05a98c6d68e Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@xxxxxx>
Date: Sat, 3 Apr 2021 18:15:29 +0200
Subject: md: split mddev_find
From: Christoph Hellwig <hch@xxxxxx>
commit 65aa97c4d2bfd76677c211b9d03ef05a98c6d68e upstream.
Split mddev_find into a simple mddev_find that just finds an existing
mddev by the unit number, and a more complicated mddev_find that deals
with find or allocating a mddev.
This turns out to fix this bug reported by Zhao Heming.
----------------------------- snip ------------------------------
commit d3374825ce57 ("md: make devices disappear when they are no longer
needed.") introduced protection between mddev creating & removing. The
md_open shouldn't create mddev when all_mddevs list doesn't contain
mddev. With currently code logic, there will be very easy to trigger
soft lockup in non-preempt env.
---
drivers/md/md.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -736,6 +736,22 @@ EXPORT_SYMBOL_GPL(mddev_init);
static struct mddev *mddev_find(dev_t unit)
{
+ struct mddev *mddev;
+
+ if (MAJOR(unit) != MD_MAJOR)
+ unit &= ~((1 << MdpMinorShift) - 1);
+
+ spin_lock(&all_mddevs_lock);
+ mddev = mddev_find_locked(unit);
+ if (mddev)
+ mddev_get(mddev);
+ spin_unlock(&all_mddevs_lock);
+
+ return mddev;
+}
+
+static struct mddev *mddev_find_or_alloc(dev_t unit)
+{
struct mddev *mddev, *new = NULL;
if (unit && MAJOR(unit) != MD_MAJOR)
@@ -5644,7 +5660,7 @@ static int md_alloc(dev_t dev, char *nam
* writing to /sys/module/md_mod/parameters/new_array.
*/
static DEFINE_MUTEX(disks_mutex);
- struct mddev *mddev = mddev_find(dev);
+ struct mddev *mddev = mddev_find_or_alloc(dev);
struct gendisk *disk;
int partitioned;
int shift;
@@ -6524,11 +6540,9 @@ static void autorun_devices(int part)
md_probe(dev);
mddev = mddev_find(dev);
- if (!mddev || !mddev->gendisk) {
- if (mddev)
- mddev_put(mddev);
+ if (!mddev)
break;
- }
+
if (mddev_lock(mddev))
pr_warn("md: %s locked, cannot run\n", mdname(mddev));
else if (mddev->raid_disks || mddev->major_version
Patches currently in stable-queue which might be from hch@xxxxxx are
queue-5.12/md-factor-out-a-mddev_find_locked-helper-from-mddev_find.patch
queue-5.12/md-split-mddev_find.patch
