| From 23e3d7f7061f8682c751c46512718f47580ad8f0 Mon Sep 17 00:00:00 2001 |
| From: Ye Bin <yebin10@huawei.com> |
| Date: Thu, 17 Mar 2022 22:21:37 +0800 |
| Subject: jbd2: fix a potential race while discarding reserved buffers after an abort |
| |
| From: Ye Bin <yebin10@huawei.com> |
| |
| commit 23e3d7f7061f8682c751c46512718f47580ad8f0 upstream. |
| |
| we got issue as follows: |
| [ 72.796117] EXT4-fs error (device sda): ext4_journal_check_start:83: comm fallocate: Detected aborted journal |
| [ 72.826847] EXT4-fs (sda): Remounting filesystem read-only |
| fallocate: fallocate failed: Read-only file system |
| [ 74.791830] jbd2_journal_commit_transaction: jh=0xffff9cfefe725d90 bh=0x0000000000000000 end delay |
| [ 74.793597] ------------[ cut here ]------------ |
| [ 74.794203] kernel BUG at fs/jbd2/transaction.c:2063! |
| [ 74.794886] invalid opcode: 0000 [#1] PREEMPT SMP PTI |
| [ 74.795533] CPU: 4 PID: 2260 Comm: jbd2/sda-8 Not tainted 5.17.0-rc8-next-20220315-dirty #150 |
| [ 74.798327] RIP: 0010:__jbd2_journal_unfile_buffer+0x3e/0x60 |
| [ 74.801971] RSP: 0018:ffffa828c24a3cb8 EFLAGS: 00010202 |
| [ 74.802694] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 |
| [ 74.803601] RDX: 0000000000000001 RSI: ffff9cfefe725d90 RDI: ffff9cfefe725d90 |
| [ 74.804554] RBP: ffff9cfefe725d90 R08: 0000000000000000 R09: ffffa828c24a3b20 |
| [ 74.805471] R10: 0000000000000001 R11: 0000000000000001 R12: ffff9cfefe725d90 |
| [ 74.806385] R13: ffff9cfefe725d98 R14: 0000000000000000 R15: ffff9cfe833a4d00 |
| [ 74.807301] FS: 0000000000000000(0000) GS:ffff9d01afb00000(0000) knlGS:0000000000000000 |
| [ 74.808338] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 |
| [ 74.809084] CR2: 00007f2b81bf4000 CR3: 0000000100056000 CR4: 00000000000006e0 |
| [ 74.810047] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 |
| [ 74.810981] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 |
| [ 74.811897] Call Trace: |
| [ 74.812241] <TASK> |
| [ 74.812566] __jbd2_journal_refile_buffer+0x12f/0x180 |
| [ 74.813246] jbd2_journal_refile_buffer+0x4c/0xa0 |
| [ 74.813869] jbd2_journal_commit_transaction.cold+0xa1/0x148 |
| [ 74.817550] kjournald2+0xf8/0x3e0 |
| [ 74.819056] kthread+0x153/0x1c0 |
| [ 74.819963] ret_from_fork+0x22/0x30 |
| |
| Above issue may happen as follows: |
| write truncate kjournald2 |
| generic_perform_write |
| ext4_write_begin |
| ext4_walk_page_buffers |
| do_journal_get_write_access ->add BJ_Reserved list |
| ext4_journalled_write_end |
| ext4_walk_page_buffers |
| write_end_fn |
| ext4_handle_dirty_metadata |
| ***************JBD2 ABORT************** |
| jbd2_journal_dirty_metadata |
| -> return -EROFS, jh in reserved_list |
| jbd2_journal_commit_transaction |
| while (commit_transaction->t_reserved_list) |
| jh = commit_transaction->t_reserved_list; |
| truncate_pagecache_range |
| do_invalidatepage |
| ext4_journalled_invalidatepage |
| jbd2_journal_invalidatepage |
| journal_unmap_buffer |
| __dispose_buffer |
| __jbd2_journal_unfile_buffer |
| jbd2_journal_put_journal_head ->put last ref_count |
| __journal_remove_journal_head |
| bh->b_private = NULL; |
| jh->b_bh = NULL; |
| jbd2_journal_refile_buffer(journal, jh); |
| bh = jh2bh(jh); |
| ->bh is NULL, later will trigger null-ptr-deref |
| journal_free_journal_head(jh); |
| |
| After commit 96f1e0974575, we no longer hold the j_state_lock while |
| iterating over the list of reserved handles in |
| jbd2_journal_commit_transaction(). This potentially allows the |
| journal_head to be freed by journal_unmap_buffer while the commit |
| codepath is also trying to free the BJ_Reserved buffers. Keeping |
| j_state_lock held while trying extends hold time of the lock |
| minimally, and solves this issue. |
| |
| Fixes: 96f1e0974575("jbd2: avoid long hold times of j_state_lock while committing a transaction") |
| Signed-off-by: Ye Bin <yebin10@huawei.com> |
| Reviewed-by: Jan Kara <jack@suse.cz> |
| Link: https://lore.kernel.org/r/20220317142137.1821590-1-yebin10@huawei.com |
| Signed-off-by: Theodore Ts'o <tytso@mit.edu> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| fs/jbd2/commit.c | 4 +++- |
| 1 file changed, 3 insertions(+), 1 deletion(-) |
| |
| --- a/fs/jbd2/commit.c |
| +++ b/fs/jbd2/commit.c |
| @@ -451,7 +451,6 @@ void jbd2_journal_commit_transaction(jou |
| } |
| spin_unlock(&commit_transaction->t_handle_lock); |
| commit_transaction->t_state = T_SWITCH; |
| - write_unlock(&journal->j_state_lock); |
| |
| J_ASSERT (atomic_read(&commit_transaction->t_outstanding_credits) <= |
| journal->j_max_transaction_buffers); |
| @@ -471,6 +470,8 @@ void jbd2_journal_commit_transaction(jou |
| * has reserved. This is consistent with the existing behaviour |
| * that multiple jbd2_journal_get_write_access() calls to the same |
| * buffer are perfectly permissible. |
| + * We use journal->j_state_lock here to serialize processing of |
| + * t_reserved_list with eviction of buffers from journal_unmap_buffer(). |
| */ |
| while (commit_transaction->t_reserved_list) { |
| jh = commit_transaction->t_reserved_list; |
| @@ -490,6 +491,7 @@ void jbd2_journal_commit_transaction(jou |
| jbd2_journal_refile_buffer(journal, jh); |
| } |
| |
| + write_unlock(&journal->j_state_lock); |
| /* |
| * Now try to drop any written-back buffers from the journal's |
| * checkpoint lists. We do this *before* commit because it potentially |