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);