This is a note to let you know that I've just added the patch titled
ext4: annotate data race in start_this_handle()
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ext4-annotate-data-race-in-start_this_handle.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 3b1833e92baba135923af4a07e73fe6e54be5a2f Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@xxxxxxx>
Date: Tue, 6 Apr 2021 18:17:59 +0200
Subject: ext4: annotate data race in start_this_handle()
From: Jan Kara <jack@xxxxxxx>
commit 3b1833e92baba135923af4a07e73fe6e54be5a2f upstream.
Access to journal->j_running_transaction is not protected by appropriate
lock and thus is racy. We are well aware of that and the code handles
the race properly. Just add a comment and data_race() annotation.
Cc: stable@xxxxxxxxxx
Reported-by: syzbot+30774a6acf6a2cf6d535@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Jan Kara <jack@xxxxxxx>
Link: https://lore.kernel.org/r/20210406161804.20150-1-jack@xxxxxxx
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/jbd2/transaction.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -349,7 +349,12 @@ static int start_this_handle(journal_t *
}
alloc_transaction:
- if (!journal->j_running_transaction) {
+ /*
+ * This check is racy but it is just an optimization of allocating new
+ * transaction early if there are high chances we'll need it. If we
+ * guess wrong, we'll retry or free unused transaction.
+ */
+ if (!data_race(journal->j_running_transaction)) {
/*
* If __GFP_FS is not present, then we may be being called from
* inside the fs writeback layer, so we MUST NOT fail.
Patches currently in stable-queue which might be from jack@xxxxxxx are
queue-5.10/ext4-fix-occasional-generic-418-failure.patch
queue-5.10/ext4-do-not-set-sb_active-in-ext4_orphan_cleanup.patch
queue-5.10/ext4-annotate-data-race-in-start_this_handle.patch
queue-5.10/ext4-fix-check-to-prevent-false-positive-report-of-incorrect-used-inodes.patch
queue-5.10/ext4-annotate-data-race-in-jbd2_journal_dirty_metadata.patch
