On 12/4/2017 5:33 PM, Jan Kara wrote:
Hello, adding Peter and Byungchul to CC since the lockdep report just looks strange and cross-release seems to be involved. Guys, how did #5 get into the lock chain and what does put_ucounts() have to do with sb_writers there? Thanks!
Hello Jan, In order to get full stack of #5, we have to pass a boot param, "crossrelease_fullstack", to the kernel. Now that it only informs put_ucounts() in the call trace, it's hard to find out what exactly happened at that time, but I can tell #5 shows: When acquire(sb_writers) in put_ucounts(), it was on the way to complete((completion)&req.done) of wait_for_completion() in devtmpfs_create_node(). If acquire(sb_writers) in put_ucounts() is stuck, then wait_for_completion() in devtmpfs_create_node() would be also stuck, since complete() being in the context of acquire(sb_writers) cannot be called. This is why cross-release added the lock chain. -- Thanks, Byungchul -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
