6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Lukas Schauer <lukas@xxxxxxxxxxx>
[ Upstream commit e95aada4cb93d42e25c30a0ef9eb2923d9711d4a ]
Commit c73be61cede5 ("pipe: Add general notification queue support") a
regression was introduced that would lock up resized pipes under certain
conditions. See the reproducer in [1].
The commit resizing the pipe ring size was moved to a different
function, doing that moved the wakeup for pipe->wr_wait before actually
raising pipe->max_usage. If a pipe was full before the resize occured it
would result in the wakeup never actually triggering pipe_write.
Set @max_usage and @nr_accounted before waking writers if this isn't a
watch queue.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=212295 [1]
Link: https://lore.kernel.org/r/20231201-orchideen-modewelt-e009de4562c6@brauner
Fixes: c73be61cede5 ("pipe: Add general notification queue support")
Reviewed-by: David Howells <dhowells@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Lukas Schauer <lukas@xxxxxxxxxxx>
[Christian Brauner <brauner@xxxxxxxxxx>: rewrite to account for watch queues]
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/pipe.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/pipe.c b/fs/pipe.c
index 603ab19b0861..a234035cc375 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -1305,6 +1305,11 @@ int pipe_resize_ring(struct pipe_inode_info *pipe, unsigned int nr_slots)
pipe->tail = tail;
pipe->head = head;
+ if (!pipe_has_watch_queue(pipe)) {
+ pipe->max_usage = nr_slots;
+ pipe->nr_accounted = nr_slots;
+ }
+
spin_unlock_irq(&pipe->rd_wait.lock);
/* This might have made more room for writers */
@@ -1356,8 +1361,6 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned int arg)
if (ret < 0)
goto out_revert_acct;
- pipe->max_usage = nr_slots;
- pipe->nr_accounted = nr_slots;
return pipe->max_usage * PAGE_SIZE;
out_revert_acct:
--
2.43.0
