linux-ext4 - [RFC PATCH] jbd2: avoid __GFP_ZERO with SLAB_TYPESAFE_BY

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Date:   Wed, 9 Feb 2022 11:57:42 -0500
From:   Qian Cai <quic_qiancai@...cinc.com>
To:     Theodore Ts'o <tytso@....edu>
CC:     Jan Kara <jack@...e.com>, "Paul E. McKenney" <paulmck@...nel.org>,
        "Neeraj Upadhyay" <quic_neeraju@...cinc.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Boqun Feng <boqun.feng@...il.com>,
        <linux-ext4@...r.kernel.org>, <rcu@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Qian Cai <quic_qiancai@...cinc.com>
Subject: [RFC PATCH] jbd2: avoid __GFP_ZERO with SLAB_TYPESAFE_BY_RCU

Since the linux-next commit 120aa5e57479 (mm: Check for
SLAB_TYPESAFE_BY_RCU and __GFP_ZERO slab allocation), we will get a
boot warning. Avoid it by calling synchronize_rcu() before the zeroing.

Signed-off-by: Qian Cai <quic_qiancai@...cinc.com>
---
 fs/jbd2/journal.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index c2cf74b01ddb..323112de5921 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -2861,15 +2861,18 @@ static struct journal_head *journal_alloc_journal_head(void)
 #ifdef CONFIG_JBD2_DEBUG
 	atomic_inc(&nr_journal_heads);
 #endif
-	ret = kmem_cache_zalloc(jbd2_journal_head_cache, GFP_NOFS);
+	ret = kmem_cache_alloc(jbd2_journal_head_cache, GFP_NOFS);
 	if (!ret) {
 		jbd_debug(1, "out of memory for journal_head\n");
 		pr_notice_ratelimited("ENOMEM in %s, retrying.\n", __func__);
-		ret = kmem_cache_zalloc(jbd2_journal_head_cache,
+		ret = kmem_cache_alloc(jbd2_journal_head_cache,
 				GFP_NOFS | __GFP_NOFAIL);
 	}
-	if (ret)
+	if (ret) {
+		synchronize_rcu();
+		memset(ret, 0, sizeof(*ret));
 		spin_lock_init(&ret->b_state_lock);
+	}
 	return ret;
 }
 
-- 
2.30.2