From 047fe3605235888f3ebcda0c728cb31937eadfe6 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 12 Jun 2012 15:24:40 +0200 Subject: splice: fix racy pipe->buffers uses Dave Jones reported a kernel BUG at mm/slub.c:3474! triggered by splice_shrink_spd() called from vmsplice_to_pipe() commit 35f3d14dbbc5 (pipe: add support for shrinking and growing pipes) added capability to adjust pipe->buffers. Problem is some paths don't hold pipe mutex and assume pipe->buffers doesn't change for their duration. Fix this by adding nr_pages_max field in struct splice_pipe_desc, and use it in place of pipe->buffers where appropriate. splice_shrink_spd() loses its struct pipe_inode_info argument. Reported-by: Dave Jones Signed-off-by: Eric Dumazet Cc: Jens Axboe Cc: Alexander Viro Cc: Tom Herbert Cc: stable # 2.6.35 Tested-by: Dave Jones Signed-off-by: Jens Axboe --- mm/shmem.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/shmem.c b/mm/shmem.c index 585bd220a21e..c244e93a70fa 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1577,6 +1577,7 @@ static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos, struct splice_pipe_desc spd = { .pages = pages, .partial = partial, + .nr_pages_max = PIPE_DEF_BUFFERS, .flags = flags, .ops = &page_cache_pipe_buf_ops, .spd_release = spd_release_page, @@ -1665,7 +1666,7 @@ static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos, if (spd.nr_pages) error = splice_to_pipe(pipe, &spd); - splice_shrink_spd(pipe, &spd); + splice_shrink_spd(&spd); if (error > 0) { *ppos += error; -- cgit v1.2.3-59-g8ed1b