FAILED: patch "[PATCH] fuse: release pipe buf after last use" failed to apply to 4.9-stable tree

The patch below does not apply to the 4.9-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 <[email protected]>.

thanks,

greg k-h

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

From 473441720c8616dfaf4451f9c7ea14f0eb5e5d65 Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <[email protected]>
Date: Thu, 25 Nov 2021 14:05:18 +0100
Subject: [PATCH] fuse: release pipe buf after last use

Checking buf->flags should be done before the pipe_buf_release() is called on the pipe buffer, since releasing the buffer might modify the flags.

This is exactly what page_cache_pipe_buf_release() does, and which results in the same VM_BUG_ON_PAGE(PageLRU(page)) that the original patch was trying to fix.

index 79f7eda49e06..cd54a529460d 100644
@@ -847,17 +847,17 @@ static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep)
 
 	replace_page_cache_page(oldpage, newpage);
 
+	get_page(newpage);
+
+	if (!(buf->flags & PIPE_BUF_FLAG_LRU))
+		lru_cache_add(newpage);
+
 	/*
 	 * Release while we have extra ref on stolen page.  Otherwise
 	 * anon_pipe_buf_release() might think the page can be reused.
 	 */
 	pipe_buf_release(cs->pipe, buf);
 
-	get_page(newpage);
-
-	if (!(buf->flags & PIPE_BUF_FLAG_LRU))
-		lru_cache_add(newpage);
-
 	err = 0;
 	spin_lock(&cs->req->waitq.lock);
 	if (test_bit(FR_ABORTED, &cs->req->flags))

Hi Greg,

Attaching the backport against 4.9.292-rc1.

Should apply to the 4.14, 4.19 and 5.4 stable trees as well.

Thanks,
Miklos

From d84c327c0f8163524407c9f182710b1d9cefb930 Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <[email protected]>
Date: Thu, 25 Nov 2021 14:05:18 +0100
Subject: [PATCH] fuse: release pipe buf after last use

Checking buf->flags should be done before the pipe_buf_release() is called on the pipe buffer, since releasing the buffer might modify the flags.

This is exactly what page_cache_pipe_buf_release() does, and which results in the same VM_BUG_ON_PAGE(PageLRU(page)) that the original patch was trying to fix.

---
 fs/fuse/dev.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

index 72ce66e0e08c..585c52dbb2e3 100644
@@ -898,17 +898,17 @@ static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep)
 		goto out_put_old;
 	}
 
+	get_page(newpage);
+
+	if (!(buf->flags & PIPE_BUF_FLAG_LRU))
+		lru_cache_add_file(newpage);
+
 	/*
 	 * Release while we have extra ref on stolen page.  Otherwise
 	 * anon_pipe_buf_release() might think the page can be reused.
 	 */
 	pipe_buf_release(cs->pipe, buf);
 
-	get_page(newpage);
-
-	if (!(buf->flags & PIPE_BUF_FLAG_LRU))
-		lru_cache_add_file(newpage);
-
 	err = 0;
 	spin_lock(&cs->req->waitq.lock);
 	if (test_bit(FR_ABORTED, &cs->req->flags))

2.31.1

Wonderful, thanks for this, now queued up.

greg k-h