[PATCH] net: bypass ->sendpage for slab pages
From: Christoph Hellwig <hch@lst.de>
Date: 2020-08-19 05:19:58
Also in:
lkml
Subsystem:
networking [general], networking [sockets], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Kuniyuki Iwashima, Willem de Bruijn, Linus Torvalds
Sending Slab or tail pages into ->sendpage will cause really strange delayed oops. Prevent it right in the networking code instead of requiring drivers to guess the exact conditions where sendpage works. Based on a patch from Coly Li [off-list ref]. Signed-off-by: Christoph Hellwig <hch@lst.de> --- net/socket.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/net/socket.c b/net/socket.c
index dbbe8ea7d395da..b4e65688915fe3 100644
--- a/net/socket.c
+++ b/net/socket.c@@ -3638,7 +3638,11 @@ EXPORT_SYMBOL(kernel_getpeername); int kernel_sendpage(struct socket *sock, struct page *page, int offset, size_t size, int flags) { - if (sock->ops->sendpage) + /* sendpage does manipulates the refcount of the sent in page, which + * does not work for Slab pages, or for tails of non-__GFP_COMP + * high order pages. + */ + if (sock->ops->sendpage && !PageSlab(page) && page_count(page) > 0) return sock->ops->sendpage(sock, page, offset, size, flags); return sock_no_sendpage(sock, page, offset, size, flags);
--
2.28.0