| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <200711292236.lATMaoSc010738@imap1.linux-foundation.org>
Date: Thu, 29 Nov 2007 14:36:50 -0800
From: akpm@...ux-foundation.org
To: mm-commits@...r.kernel.org
Cc: jack@...e.cz, linux-ext4@...r.kernel.org
Subject: + jbd2-fix-assertion-failure-in-fs-jbd2-checkpointc.patch added to -mm tree
The patch titled
jbd2: Fix assertion failure in fs/jbd2/checkpoint.c
has been added to the -mm tree. Its filename is
jbd2-fix-assertion-failure-in-fs-jbd2-checkpointc.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: jbd2: Fix assertion failure in fs/jbd2/checkpoint.c
From: Jan Kara <jack@...e.cz>
Before we start committing a transaction, we call
__journal_clean_checkpoint_list() to cleanup transaction's written-back
buffers.
If this call happens to remove all of them (and there were already some
buffers), __journal_remove_checkpoint() will decide to free the transaction
because it isn't (yet) a committing transaction and soon we fail some
assertion - the transaction really isn't ready to be freed :).
We change the check in __journal_remove_checkpoint() to free only a
transaction in T_FINISHED state. The locking there is subtle though (as
everywhere in JBD ;(). We use j_list_lock to protect the check and a
subsequent call to __journal_drop_transaction() and do the same in the end
of journal_commit_transaction() which is the only place where a transaction
can get to T_FINISHED state.
Probably I'm too paranoid here and such locking is not really necessary -
checkpoint lists are processed only from log_do_checkpoint() where a
transaction must be already committed to be processed or from
__journal_clean_checkpoint_list() where kjournald itself calls it and thus
transaction cannot change state either. Better be safe if something
changes in future...
Signed-off-by: Jan Kara <jack@...e.cz>
Cc: <linux-ext4@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---
fs/jbd2/checkpoint.c | 12 ++++++------
fs/jbd2/commit.c | 8 ++++----
include/linux/jbd2.h | 2 ++
3 files changed, 12 insertions(+), 10 deletions(-)
diff -puN fs/jbd2/checkpoint.c~jbd2-fix-assertion-failure-in-fs-jbd2-checkpointc fs/jbd2/checkpoint.c
--- a/fs/jbd2/checkpoint.c~jbd2-fix-assertion-failure-in-fs-jbd2-checkpointc
+++ a/fs/jbd2/checkpoint.c
@@ -608,15 +608,15 @@ int __jbd2_journal_remove_checkpoint(str
/*
* There is one special case to worry about: if we have just pulled the
- * buffer off a committing transaction's forget list, then even if the
- * checkpoint list is empty, the transaction obviously cannot be
- * dropped!
+ * buffer off a running or committing transaction's checkpoing list,
+ * then even if the checkpoint list is empty, the transaction obviously
+ * cannot be dropped!
*
- * The locking here around j_committing_transaction is a bit sleazy.
+ * The locking here around t_state is a bit sleazy.
* See the comment at the end of jbd2_journal_commit_transaction().
*/
- if (transaction == journal->j_committing_transaction) {
- JBUFFER_TRACE(jh, "belongs to committing transaction");
+ if (transaction->t_state != T_FINISHED) {
+ JBUFFER_TRACE(jh, "belongs to running/committing transaction");
goto out;
}
diff -puN fs/jbd2/commit.c~jbd2-fix-assertion-failure-in-fs-jbd2-checkpointc fs/jbd2/commit.c
--- a/fs/jbd2/commit.c~jbd2-fix-assertion-failure-in-fs-jbd2-checkpointc
+++ a/fs/jbd2/commit.c
@@ -971,10 +971,10 @@ restart_loop:
}
spin_unlock(&journal->j_list_lock);
/*
- * This is a bit sleazy. We borrow j_list_lock to protect
- * journal->j_committing_transaction in __jbd2_journal_remove_checkpoint.
- * Really, __jbd2_journal_remove_checkpoint should be using j_state_lock but
- * it's a bit hassle to hold that across __jbd2_journal_remove_checkpoint
+ * This is a bit sleazy. We use j_list_lock to protect transition
+ * of a transaction into T_FINISHED state and calling
+ * __jbd2_journal_drop_transaction(). Otherwise we could race with
+ * other checkpointing code processing the transaction...
*/
spin_lock(&journal->j_state_lock);
spin_lock(&journal->j_list_lock);
diff -puN include/linux/jbd2.h~jbd2-fix-assertion-failure-in-fs-jbd2-checkpointc include/linux/jbd2.h
--- a/include/linux/jbd2.h~jbd2-fix-assertion-failure-in-fs-jbd2-checkpointc
+++ a/include/linux/jbd2.h
@@ -479,6 +479,8 @@ struct transaction_s
/*
* Transaction's current state
* [no locking - only kjournald2 alters this]
+ * [j_list_lock] guards transition of a transaction into T_FINISHED
+ * state and subsequent call of __jbd2_journal_drop_transaction()
* FIXME: needs barriers
* KLUDGE: [use j_state_lock]
*/
_
Patches currently in -mm which might be from jack@...e.cz are
origin.patch
jbd-fix-assertion-failure-in-fs-jbd-checkpointc.patch
inotify-send-in_attrib-events-when-link-count-changes.patch
jbd2-fix-assertion-failure-in-fs-jbd2-checkpointc.patch
r-o-bind-mounts-elevate-write-count-for-some-ioctls-vs-forbid-user-to-change-file-flags-on-quota-files.patch
iget-stop-ext3-from-using-iget-and-read_inode-try.patch
iget-stop-ext3-from-using-iget-and-read_inode-try-checkpatch-fixes.patch
iget-stop-ext4-from-using-iget-and-read_inode-try.patch
-
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists