FAILED: patch "[PATCH] maple_tree: remove rcu_read_lock() from mt_validate()" failed to apply to 6.1-stable tree

FAILED: patch "[PATCH] maple_tree: remove rcu_read_lock() from mt_validate()" failed to apply to 6.1-stable tree

[gregkh]

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x f806de88d8f7f8191afd0fd9b94db4cd058e7d4f
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024090851-coroner-surname-cd39@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

f806de88d8f7 ("maple_tree: remove rcu_read_lock() from mt_validate()")
9a40d45c1f2c ("maple_tree: remove mas_searchable()")
067311d33e65 ("maple_tree: separate ma_state node from status")
271f61a8b41d ("maple_tree: clean up inlines for some functions")
bf857ddd21d0 ("maple_tree: move debug check to __mas_set_range()")
f7a590189539 ("maple_tree: make mas_erase() more robust")
a2587a7e8d37 ("maple_tree: add test for mtree_dup()")
fd32e4e9b764 ("maple_tree: introduce interfaces __mt_dup() and mtree_dup()")
4f2267b58a22 ("maple_tree: add mt_free_one() and mt_attr() helpers")
a8091f039c1e ("maple_tree: add MAS_UNDERFLOW and MAS_OVERFLOW states")
5c590804b6b0 ("maple_tree: add mas_is_active() to detect in-tree walks")
530f745c7620 ("maple_tree: replace data before marking dead in split and spanning store")
4ffc2ee2cf01 ("maple_tree: introduce mas_tree_parent() definition")
1238f6a226dc ("maple_tree: introduce mas_put_in_tree()")
72bcf4aa86ec ("maple_tree: reorder replacement of nodes to avoid live lock")
fec29364348f ("maple_tree: reduce resets during store setup")
da0892547b10 ("maple_tree: re-introduce entry to mas_preallocate() arguments")
53bee98d004f ("mm: remove re-walk from mmap_region()")
c1297987cc2a ("maple_tree: introduce __mas_set_range()")
a489539e33c2 ("maple_tree: update mt_validate()")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f806de88d8f7f8191afd0fd9b94db4cd058e7d4f Mon Sep 17 00:00:00 2001
From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>
Date: Tue, 20 Aug 2024 13:54:17 -0400
Subject: [PATCH] maple_tree: remove rcu_read_lock() from mt_validate()

The write lock should be held when validating the tree to avoid updates
racing with checks.  Holding the rcu read lock during a large tree
validation may also cause a prolonged rcu read window and "rcu_preempt
detected stalls" warnings.

Link: https://lore.kernel.org/all/0000000000001d12d4062005aea1@google.com/
Link: https://lkml.kernel.org/r/20240820175417.2782532-1-Liam.Howlett@oracle.com
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reported-by: syzbot+036af2f0c7338a33b0cd@syzkaller.appspotmail.com
Cc: Hillf Danton <hdanton@sina.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index aa3a5df15b8e..6df3a8b95808 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -7566,14 +7566,14 @@ static void mt_validate_nulls(struct maple_tree *mt)
  * 2. The gap is correctly set in the parents
  */
 void mt_validate(struct maple_tree *mt)
+	__must_hold(mas->tree->ma_lock)
 {
 	unsigned char end;
 
 	MA_STATE(mas, mt, 0, 0);
-	rcu_read_lock();
 	mas_start(&mas);
 	if (!mas_is_active(&mas))
-		goto done;
+		return;
 
 	while (!mte_is_leaf(mas.node))
 		mas_descend(&mas);
@@ -7594,9 +7594,6 @@ void mt_validate(struct maple_tree *mt)
 		mas_dfs_postorder(&mas, ULONG_MAX);
 	}
 	mt_validate_nulls(mt);
-done:
-	rcu_read_unlock();
-
 }
 EXPORT_SYMBOL_GPL(mt_validate);