[Ocfs2-devel] [PATCH] ocfs2: fix deadlock due to wrong locking order
alex chen
alex.chen at huawei.com
Wed Sep 24 02:41:37 PDT 2014
Hi Junxiao,
On 2014/9/10 9:48, Junxiao Bi wrote:
> For commit ocfs2 journal, ocfs2 journal thread will acquire the mutex
> osb->journal->j_trans_barrier and wake up jbd2 commit thread, then it
> will wait until jbd2 commit thread done. In order journal mode, jbd2
> needs flushing dirty data pages first, and this needs get page lock.
> So osb->journal->j_trans_barrier should be got before page lock.
>
> But ocfs2_write_zero_page() and ocfs2_write_begin_inline() obey this
> locking order, and this will cause deadlock and hung the whole cluster.
>
> One deadlock catched is the following:
>
> PID: 13449 TASK: ffff8802e2f08180 CPU: 31 COMMAND: "oracle"
> #0 [ffff8802ee3f79b0] __schedule at ffffffff8150a524
> #1 [ffff8802ee3f7a58] schedule at ffffffff8150acbf
> #2 [ffff8802ee3f7a68] rwsem_down_failed_common at ffffffff8150cb85
> #3 [ffff8802ee3f7ad8] rwsem_down_read_failed at ffffffff8150cc55
> #4 [ffff8802ee3f7ae8] call_rwsem_down_read_failed at ffffffff812617a4
> #5 [ffff8802ee3f7b50] ocfs2_start_trans at ffffffffa0498919 [ocfs2]
> #6 [ffff8802ee3f7ba0] ocfs2_zero_start_ordered_transaction at ffffffffa048b2b8 [ocfs2]
> #7 [ffff8802ee3f7bf0] ocfs2_write_zero_page at ffffffffa048e9bd [ocfs2]
> #8 [ffff8802ee3f7c80] ocfs2_zero_extend_range at ffffffffa048ec83 [ocfs2]
> #9 [ffff8802ee3f7ce0] ocfs2_zero_extend at ffffffffa048edfd [ocfs2]
> #10 [ffff8802ee3f7d50] ocfs2_extend_file at ffffffffa049079e [ocfs2]
> #11 [ffff8802ee3f7da0] ocfs2_setattr at ffffffffa04910ed [ocfs2]
> #12 [ffff8802ee3f7e70] notify_change at ffffffff81187d29
> #13 [ffff8802ee3f7ee0] do_truncate at ffffffff8116bbc1
> #14 [ffff8802ee3f7f50] sys_ftruncate at ffffffff8116bcbd
> #15 [ffff8802ee3f7f80] system_call_fastpath at ffffffff81515142
> RIP: 00007f8de750c6f7 RSP: 00007fffe786e478 RFLAGS: 00000206
> RAX: 000000000000004d RBX: ffffffff81515142 RCX: 0000000000000000
> RDX: 0000000000000200 RSI: 0000000000028400 RDI: 000000000000000d
> RBP: 00007fffe786e040 R8: 0000000000000000 R9: 000000000000000d
> R10: 0000000000000000 R11: 0000000000000206 R12: 000000000000000d
> R13: 00007fffe786e710 R14: 00007f8de70f8340 R15: 0000000000028400
> ORIG_RAX: 000000000000004d CS: 0033 SS: 002b
>
> crash64> bt
> PID: 7610 TASK: ffff88100fd56140 CPU: 1 COMMAND: "ocfs2cmt"
> #0 [ffff88100f4d1c50] __schedule at ffffffff8150a524
> #1 [ffff88100f4d1cf8] schedule at ffffffff8150acbf
> #2 [ffff88100f4d1d08] jbd2_log_wait_commit at ffffffffa01274fd [jbd2]
> #3 [ffff88100f4d1d98] jbd2_journal_flush at ffffffffa01280b4 [jbd2]
> #4 [ffff88100f4d1dd8] ocfs2_commit_cache at ffffffffa0499b14 [ocfs2]
> #5 [ffff88100f4d1e38] ocfs2_commit_thread at ffffffffa0499d38 [ocfs2]
> #6 [ffff88100f4d1ee8] kthread at ffffffff81090db6
> #7 [ffff88100f4d1f48] kernel_thread_helper at ffffffff81516284
>
> crash64> bt
> PID: 7609 TASK: ffff88100f2d4480 CPU: 0 COMMAND: "jbd2/dm-20-86"
> #0 [ffff88100def3920] __schedule at ffffffff8150a524
> #1 [ffff88100def39c8] schedule at ffffffff8150acbf
> #2 [ffff88100def39d8] io_schedule at ffffffff8150ad6c
> #3 [ffff88100def39f8] sleep_on_page at ffffffff8111069e
> #4 [ffff88100def3a08] __wait_on_bit_lock at ffffffff8150b30a
> #5 [ffff88100def3a58] __lock_page at ffffffff81110687
> #6 [ffff88100def3ab8] write_cache_pages at ffffffff8111b752
> #7 [ffff88100def3be8] generic_writepages at ffffffff8111b901
> #8 [ffff88100def3c48] journal_submit_data_buffers at ffffffffa0120f67 [jbd2]
> #9 [ffff88100def3cf8] jbd2_journal_commit_transaction at ffffffffa0121372[jbd2]
> #10 [ffff88100def3e68] kjournald2 at ffffffffa0127a86 [jbd2]
> #11 [ffff88100def3ee8] kthread at ffffffff81090db6
> #12 [ffff88100def3f48] kernel_thread_helper at ffffffff81516284
>
> Signed-off-by: Junxiao Bi <junxiao.bi at oracle.com>
> ---
> fs/ocfs2/aops.c | 15 ++++++++-------
> fs/ocfs2/file.c | 52 ++++++++++++++++++++++++----------------------------
> 2 files changed, 32 insertions(+), 35 deletions(-)
>
> diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
> index c04183b..c71174a 100644
> --- a/fs/ocfs2/aops.c
> +++ b/fs/ocfs2/aops.c
> @@ -1485,8 +1485,16 @@ static int ocfs2_write_begin_inline(struct address_space *mapping,
> handle_t *handle;
> struct ocfs2_dinode *di = (struct ocfs2_dinode *)wc->w_di_bh->b_data;
>
> + handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
> + if (IS_ERR(handle)) {
> + ret = PTR_ERR(handle);
> + mlog_errno(ret);
> + goto out;
> + }
> +
> page = find_or_create_page(mapping, 0, GFP_NOFS);
> if (!page) {
> + ocfs2_commit_trans(osb, handle);
> ret = -ENOMEM;
> mlog_errno(ret);
> goto out;
> @@ -1498,13 +1506,6 @@ static int ocfs2_write_begin_inline(struct address_space *mapping,
> wc->w_pages[0] = wc->w_target_page = page;
> wc->w_num_pages = 1;
>
> - handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
> - if (IS_ERR(handle)) {
> - ret = PTR_ERR(handle);
> - mlog_errno(ret);
> - goto out;
> - }
> -
> ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), wc->w_di_bh,
> OCFS2_JOURNAL_ACCESS_WRITE);
> if (ret) {
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index 2930e23..c534cb0 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -760,7 +760,7 @@ static int ocfs2_write_zero_page(struct inode *inode, u64 abs_from,
> struct address_space *mapping = inode->i_mapping;
> struct page *page;
> unsigned long index = abs_from >> PAGE_CACHE_SHIFT;
> - handle_t *handle = NULL;
> + handle_t *handle;
> int ret = 0;
> unsigned zero_from, zero_to, block_start, block_end;
> struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
> @@ -769,11 +769,17 @@ static int ocfs2_write_zero_page(struct inode *inode, u64 abs_from,
> BUG_ON(abs_to > (((u64)index + 1) << PAGE_CACHE_SHIFT));
> BUG_ON(abs_from & (inode->i_blkbits - 1));
>
> + handle = ocfs2_zero_start_ordered_transaction(inode, di_bh);
> + if (IS_ERR(handle)) {
> + ret = PTR_ERR(handle);
> + goto out;
> + }
> +
The ocfs2_zero_start_ordered_transaction may return NULL.
> page = find_or_create_page(mapping, index, GFP_NOFS);
> if (!page) {
> ret = -ENOMEM;
> mlog_errno(ret);
> - goto out;
> + goto out_commit_trans;
> }
>
> /* Get the offsets within the page that we want to zero */
> @@ -805,15 +811,6 @@ static int ocfs2_write_zero_page(struct inode *inode, u64 abs_from,
> goto out_unlock;
> }
>
> - if (!handle) {
> - handle = ocfs2_zero_start_ordered_transaction(inode,
> - di_bh);
> - if (IS_ERR(handle)) {
> - ret = PTR_ERR(handle);
> - handle = NULL;
> - break;
> - }
> - }
>
> /* must not update i_size! */
> ret = block_commit_write(page, block_start + 1,
> @@ -824,27 +821,26 @@ static int ocfs2_write_zero_page(struct inode *inode, u64 abs_from,
> ret = 0;
> }
>
> - if (handle) {
> - /*
> - * fs-writeback will release the dirty pages without page lock
> - * whose offset are over inode size, the release happens at
> - * block_write_full_page().
> - */
> - i_size_write(inode, abs_to);
> - inode->i_blocks = ocfs2_inode_sector_count(inode);
> - di->i_size = cpu_to_le64((u64)i_size_read(inode));
> - inode->i_mtime = inode->i_ctime = CURRENT_TIME;
> - di->i_mtime = di->i_ctime = cpu_to_le64(inode->i_mtime.tv_sec);
> - di->i_ctime_nsec = cpu_to_le32(inode->i_mtime.tv_nsec);
> - di->i_mtime_nsec = di->i_ctime_nsec;
> - ocfs2_journal_dirty(handle, di_bh);
> - ocfs2_update_inode_fsync_trans(handle, inode, 1);
> - ocfs2_commit_trans(OCFS2_SB(inode->i_sb), handle);
> - }
> + /*
> + * fs-writeback will release the dirty pages without page lock
> + * whose offset are over inode size, the release happens at
> + * block_write_full_page().
> + */
> + i_size_write(inode, abs_to);
> + inode->i_blocks = ocfs2_inode_sector_count(inode);
> + di->i_size = cpu_to_le64((u64)i_size_read(inode));
> + inode->i_mtime = inode->i_ctime = CURRENT_TIME;
> + di->i_mtime = di->i_ctime = cpu_to_le64(inode->i_mtime.tv_sec);
> + di->i_ctime_nsec = cpu_to_le32(inode->i_mtime.tv_nsec);
> + di->i_mtime_nsec = di->i_ctime_nsec;
> + ocfs2_journal_dirty(handle, di_bh);
> + ocfs2_update_inode_fsync_trans(handle, inode, 1);
if ocfs2_zero_start_ordered_transaction return NULL, here will BUG.
so should judge if handle is NULL.
>
> out_unlock:
> unlock_page(page);
> page_cache_release(page);
> +out_commit_trans:
> + ocfs2_commit_trans(OCFS2_SB(inode->i_sb), handle);
if ocfs2_zero_start_ordered_transaction return NULL, here will BUG.
so should judge if handle is NULL.
> out:
> return ret;
> }
>
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