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53cf978457
This issue was found when I tried to put checkpoint work in a separate thread,
the deadlock below happened:
Thread1 | Thread2
__jbd2_log_wait_for_space |
jbd2_log_do_checkpoint (hold j_checkpoint_mutex)|
if (jh->b_transaction != NULL) |
... |
jbd2_log_start_commit(journal, tid); |jbd2_update_log_tail
| will lock j_checkpoint_mutex,
| but will be blocked here.
|
jbd2_log_wait_commit(journal, tid); |
wait_event(journal->j_wait_done_commit, |
!tid_gt(tid, journal->j_commit_sequence)); |
... |wake_up(j_wait_done_commit)
} |
then deadlock occurs, Thread1 will never be waken up.
To fix this issue, drop j_checkpoint_mutex in jbd2_log_do_checkpoint()
when we are going to wait for transaction commit.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.