Commit 47344172 authored Nov 25, 2021 by Miklos Szeredi

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.

Reported-by: Justin Forbes <jmforbes@linuxtx.org>
Fixes: 712a9510 ("fuse: fix page stealing")
Cc: <stable@vger.kernel.org> # v2.6.35
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

parent fa55b7dc

fs/fuse/dev.c

+5 −5

Original line number	Diff line number	Diff line
		@@ -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))