This is a note to let you know that I've just added the patch titled fuse: release pipe buf after last use to the 4.4-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: fuse-release-pipe-buf-after-last-use.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 473441720c8616dfaf4451f9c7ea14f0eb5e5d65 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi <mszeredi@xxxxxxxxxx> Date: Thu, 25 Nov 2021 14:05:18 +0100 Subject: fuse: release pipe buf after last use From: Miklos Szeredi <mszeredi@xxxxxxxxxx> commit 473441720c8616dfaf4451f9c7ea14f0eb5e5d65 upstream. 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. Reported-by: Justin Forbes <jmforbes@xxxxxxxxxxx> Fixes: 712a951025c0 ("fuse: fix page stealing") Cc: <stable@xxxxxxxxxxxxxxx> # v2.6.35 Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/fuse/dev.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -903,6 +903,11 @@ static int fuse_try_move_page(struct fus if (fuse_check_page(newpage) != 0) goto out_fallback_unlock; + page_cache_get(newpage); + + if (!(buf->flags & PIPE_BUF_FLAG_LRU)) + lru_cache_add_file(newpage); + /* * This is a new and locked page, it shouldn't be mapped or * have any special flags on it @@ -922,11 +927,6 @@ static int fuse_try_move_page(struct fus return err; } - page_cache_get(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)) Patches currently in stable-queue which might be from mszeredi@xxxxxxxxxx are queue-4.4/fuse-release-pipe-buf-after-last-use.patch