Re: bcache: register_cache() error opening sdh2: cannot allocate memory => BUG NULL pointer
From: Eric Wheeler <hidden>
Date: 2016-02-25 07:29:38
Subsystem:
bcache (block layer cache), the rest · Maintainers:
Coly Li, Kent Overstreet, Linus Torvalds
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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