On Fri, Jun 5, 2009 at 12:26 PM, Jeff Mahoney<jeffm@xxxxxxxx> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Trenton D. Adams wrote: >> On Sat, May 16, 2009 at 12:02 PM, Frederic Weisbecker >> <fweisbec@xxxxxxxxx> wrote: >>> While searching a pathname, an inode mutex can be acquired >>> in do_lookup() which calls reiserfs_lookup() which in turn >>> acquires the write lock. >>> >>> On the other side reiserfs_fill_super() can acquire the write_lock >>> and then call reiserfs_lookup_privroot() which can acquire an >>> inode mutex (the root of the mount point). >>> >>> So we theoretically risk an AB - BA lock inversion that could lead >>> to a deadlock. >>> >>> As for other lock dependencies found since the bkl to mutex >>> conversion, the fix is to use reiserfs_mutex_lock_safe() which >>> drops the lock dependency to the write lock. >>> >> >> I'm curious, did this get applied, and is it related to the following? >> I was having these in 2.6.30-rc3. I am now on 2.6.30-rc7 as of >> today. I haven't seen them today. But then again, I only seen this >> happen one time. >> >> May 27 01:56:12 tdamac INFO: task pdflush:15370 blocked for more than >> 120 seconds. >> May 27 01:56:12 tdamac "echo 0 > >> /proc/sys/kernel/hung_task_timeout_secs" disables this message. >> May 27 01:56:12 tdamac pdflush D ffff8800518a0000 0 15370 2 >> May 27 01:56:12 tdamac ffff880025023b50 0000000000000046 >> 0000000025023a90 000000000000d7a0 >> May 27 01:56:12 tdamac 0000000000004000 0000000000011440 >> 000000000000ca78 ffff880045e71568 >> May 27 01:56:12 tdamac ffff880045e7156c ffff8800518a0000 >> ffff880067f54230 ffff8800518a0380 >> May 27 01:56:12 tdamac Call Trace: >> May 27 01:56:12 tdamac [<ffffffff80687d1b>] ? __mutex_lock_slowpath+0xe2/0x124 >> May 27 01:56:12 tdamac [<ffffffff80687d13>] __mutex_lock_slowpath+0xda/0x124 >> May 27 01:56:12 tdamac [<ffffffff8068809e>] mutex_lock+0x1e/0x36 >> May 27 01:56:12 tdamac [<ffffffff803087ae>] flush_commit_list+0x150/0x689 >> May 27 01:56:12 tdamac [<ffffffff8022f8e5>] ? __wake_up+0x43/0x50 >> May 27 01:56:12 tdamac [<ffffffff8030ad8a>] do_journal_end+0xb4a/0xd6c >> May 27 01:56:12 tdamac [<ffffffff8023053d>] ? dequeue_entity+0x1b/0x1df >> May 27 01:56:12 tdamac [<ffffffff8030b020>] journal_end_sync+0x74/0x7d >> May 27 01:56:12 tdamac [<ffffffff802fd2fd>] reiserfs_sync_fs+0x41/0x67 >> May 27 01:56:12 tdamac [<ffffffff80688091>] ? mutex_lock+0x11/0x36 >> May 27 01:56:12 tdamac [<ffffffff802fd331>] reiserfs_write_super+0xe/0x10 >> May 27 01:56:12 tdamac [<ffffffff802a532a>] sync_supers+0x61/0xa6 >> May 27 01:56:12 tdamac [<ffffffff8027e140>] wb_kupdate+0x32/0x128 >> May 27 01:56:12 tdamac [<ffffffff8027ee7c>] pdflush+0x140/0x21f >> May 27 01:56:12 tdamac [<ffffffff8027e10e>] ? wb_kupdate+0x0/0x128 >> May 27 01:56:12 tdamac [<ffffffff8027ed3c>] ? pdflush+0x0/0x21f >> May 27 01:56:12 tdamac [<ffffffff8024fb26>] kthread+0x56/0x83 >> May 27 01:56:12 tdamac [<ffffffff8020beba>] child_rip+0xa/0x20 >> May 27 01:56:12 tdamac [<ffffffff8024fad0>] ? kthread+0x0/0x83 >> May 27 01:56:12 tdamac [<ffffffff8020beb0>] ? child_rip+0x0/0x20 > > Can you capture a sysrq+t when this happens? The lock is properly > released, but I have a hunch that another thread is doing ordered > writeback that's taking a while. That happens under the j_commit_mutex. FYI: I never did anything specific that I knew of, so I didn't actually notice a delay. I was rsyncing to a USB key at the time. And seeing it took over an hour, I walked away, so I wouldn't have noticed it. But, I could fiddle around a little to see if I could get some sort of delay going on. Any ideas on what I should try? Then I can do the sysreq+t for you if I can reproduce. -- To unsubscribe from this list: send the line "unsubscribe reiserfs-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
