Bug #4722
closed
kernel BUG at fs/ceph/caps.c:1006 invalid opcode: 0000
Added by Matthew Roy about 11 years ago.
Updated almost 8 years ago.
Description
Top of Call trace:
ceph_queue_caps_release
ceph_destroy_inode
evict
input
d_kill
shrink_dentry_list
prune_dcache_sb
prune_super
shrink_slab
This roughly coincided with some MDS/mon crashes. Crash occurred on Ubuntu 12.10 (3.5 series), but this line looks last modified in 2010, so this might still be present.
Unfortunately none of this made it into the logfiles, screenshots attached and at https://plus.google.com/102493641635816029247/posts/SpiK8kPAyuX
Files
I did a checkout of v3.5, and caps.c:1006 is
BUG_ON(msg->front.iov_len + sizeof(*item) > PAGE_CACHE_SIZE);
Alex tells me this matches up with the invalid opcode (probably; he's not sure the code is the right one), so I guess that's good? He's not sure whether it matters that the message front is larger than a page (I have no idea, kernel-side), but this happened following some MDS trouble so it makes sense that the client could be instructed to drop >4KB worth of encoded caps.
Thanks for the report!
- Category set to 53
- Priority changed from Normal to High
Sounds like this might require some protocol work and it's in the kernel client — high!
Unless this part has been fixed by a newer kernel, we still need to deal with it. In particular we were concerned that this BUG_ON might be because we always pre-allocate the space needed for a message reply, but with this message the "front" portion can sometimes be bigger than the allocated space.
- Status changed from New to Can't reproduce
it's more likely there is no pre-allocated message. variable 'msg' is pointing to the pre-allocated message list.
You think the msg pointer is invalid, and so it's overflowing?
I'm a little concerned at just closing this unless we can guarantee the size of a cap drop message is effectively limited by something, which I don't believe we've changed recently.
__queue_cap_release has code which limits the size of cap release message
- Component(FS) kceph added
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