This is a note to let you know that I've just added the patch titled
pipe: wakeup wr_wait after setting max_usage
to the 6.7-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:
pipe-wakeup-wr_wait-after-setting-max_usage.patch
and it can be found in the queue-6.7 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e95aada4cb93d42e25c30a0ef9eb2923d9711d4a Mon Sep 17 00:00:00 2001
From: Lukas Schauer <lukas@xxxxxxxxxxx>
Date: Fri, 1 Dec 2023 11:11:28 +0100
Subject: pipe: wakeup wr_wait after setting max_usage
From: Lukas Schauer <lukas@xxxxxxxxxxx>
commit e95aada4cb93d42e25c30a0ef9eb2923d9711d4a upstream.
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: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/pipe.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -1324,6 +1324,11 @@ int pipe_resize_ring(struct pipe_inode_i
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 */
@@ -1375,8 +1380,6 @@ static long pipe_set_size(struct pipe_in
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:
Patches currently in stable-queue which might be from lukas@xxxxxxxxxxx are
queue-6.7/pipe-wakeup-wr_wait-after-setting-max_usage.patch
