The patch below does not apply to the 5.15-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-5.15.y git checkout FETCH_HEAD git cherry-pick -x e95aada4cb93d42e25c30a0ef9eb2923d9711d4a # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024012610-lustiness-grew-ee5c@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..
Possible dependencies:
e95aada4cb93 ("pipe: wakeup wr_wait after setting max_usage") 189b0ddc2451 ("pipe: Fix missing lock in pipe_resize_ring()")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From e95aada4cb93d42e25c30a0ef9eb2923d9711d4a Mon Sep 17 00:00:00 2001 From: Lukas Schauer lukas@schauer.dev Date: Fri, 1 Dec 2023 11:11:28 +0100 Subject: [PATCH] pipe: wakeup wr_wait after setting max_usage
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@redhat.com Cc: stable@vger.kernel.org Signed-off-by: Lukas Schauer lukas@schauer.dev [Christian Brauner brauner@kernel.org: rewrite to account for watch queues] Signed-off-by: Christian Brauner brauner@kernel.org
diff --git a/fs/pipe.c b/fs/pipe.c index 226e7f66b590..8d9286a1f2e8 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -1324,6 +1324,11 @@ 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 */ @@ -1375,8 +1380,6 @@ 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: