On Wed, 24 Feb 2016, Marc MERLIN wrote:
> I understand I have an underlying memory problem, but could bcache handle
> memory issues and not crash on null pointer?
Try this patch. It adds some error handling:
=======================================================================================
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index a542b58..5d95816 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1829,11 +1829,12 @@ static int cache_alloc(struct cache_sb *sb, struct cache *ca)
return 0;
}
-static void register_cache(struct cache_sb *sb, struct page *sb_page,
+static int register_cache(struct cache_sb *sb, struct page *sb_page,
struct block_device *bdev, struct cache *ca)
{
char name[BDEVNAME_SIZE];
- const char *err = "cannot allocate memory";
+ const char *err = NULL;
+ int ret = 0;
memcpy(&ca->sb, sb, sizeof(struct cache_sb));
ca->bdev = bdev;
@@ -1848,27 +1849,34 @@ static void register_cache(struct cache_sb *sb, struct page *sb_page,
if (blk_queue_discard(bdev_get_queue(ca->bdev)))
ca->discard = CACHE_DISCARD(&ca->sb);
- if (cache_alloc(sb, ca) != 0)
+ if ((ret = cache_alloc(sb, ca)) != 0)
goto err;
- err = "error creating kobject";
- if (kobject_add(&ca->kobj, &part_to_dev(bdev->bd_part)->kobj, "bcache"))
- goto err;
+ if (kobject_add(&ca->kobj, &part_to_dev(bdev->bd_part)->kobj, "bcache")) {
+ err = "error calling kobject_add";
+ ret = -ENOMEM;
+ goto out;
+ }
mutex_lock(&bch_register_lock);
err = register_cache_set(ca);
mutex_unlock(&bch_register_lock);
- if (err)
- goto err;
-
+ if (err) {
+ ret = -ENODEV;
+ goto out;
+ }
+
pr_info("registered cache device %s", bdevname(bdev, name));
+
out:
kobject_put(&ca->kobj);
- return;
+
err:
- pr_notice("error opening %s: %s", bdevname(bdev, name), err);
- goto out;
+ if (err)
+ pr_notice("error opening %s: %s", bdevname(bdev, name), err);
+
+ return ret;
}
/* Global interfaces/init */
@@ -1964,7 +1972,8 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
if (!ca)
goto err_close;
- register_cache(sb, sb_page, bdev, ca);
+ if (register_cache(sb, sb_page, bdev, ca) != 0)
+ goto err_close;
}
out:
if (sb_page)
===================================================================
-Eric
>
> gargamel:/sys/block/md5/bcache# echo /dev/sdh2 > /sys/fs/bcache/register
> gave:
> bcache: register_cache() error opening sdh2: cannot allocate memory
> BUG: unable to handle kernel NULL pointer dereference at 00000000000009b8
> IP: [<ffffffffc05a7e8d>] cache_set_flush+0x102/0x15c [bcache]
> PGD 120dff067 PUD 1119a3067 PMD 0
> Oops: 0000 [#1] SMP
> Modules linked in: veth ip6table_filter ip6_tables
> (...)
> CPU: 4 PID: 3371 Comm: kworker/4:3 Not tainted 4.4.2-amd64-i915-volpreempt-20160213bc1 #3
> Hardware name: System manufacturer System Product Name/P8H67-M PRO, BIOS 3904 04/27/2013
> Workqueue: events cache_set_flush [bcache]
> task: ffff88020d5dc280 ti: ffff88020b6f8000 task.ti: ffff88020b6f8000
> RIP: 0010:[<ffffffffc05a7e8d>] [<ffffffffc05a7e8d>] cache_set_flush+0x102/0x15c [bcache]
>
> Thanks,
> Marc
> --
> "A mouse is a device used to point at the xterm you want to type in" - A.S.R.
> Microsoft is to operating systems ....
> .... what McDonalds is to gourmet cooking
> Home page: http://marc.merlins.org/
> --
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