The original problem was from nvme-over-tcp code, who mistakenly uses
kernel_sendpage() to send pages allocated by __get_free_pages() without
__GFP_COMP flag. Such pages don't have refcount (page_count is 0) on
tail pages, sending them by kernel_sendpage() may trigger a kernel panic
from a corrupted kernel heap, because these pages are incorrectly freed
in network stack as page_count 0 pages.
This patch introduces a helper sendpage_ok(), it returns true if the
checking page,
- is not slab page: PageSlab(page) is false.
- has page refcount: page_count(page) is not zero
All drivers who want to send page to remote end by kernel_sendpage()
may use this helper to check whether the page is OK. If the helper does
not return true, the driver should try other non sendpage method (e.g.
sock_no_sendpage()) to handle the page.
Signed-off-by: Coly Li <redacted>
Cc: Chaitanya Kulkarni <redacted>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Jan Kara <jack@suse.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Mikhail Skorzhinskii <redacted>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Vlastimil Babka <redacted>
Cc: stable@vger.kernel.org
---
include/linux/net.h | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/include/linux/net.h b/include/linux/net.h
index d48ff1180879..97e8f1a8a427 100644
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -286,6 +286,21 @@ do { \
#define net_get_random_once_wait(buf, nbytes) \
get_random_once_wait((buf), (nbytes))
+/*
+ * E.g. XFS meta- & log-data is in slab pages, or bcache meta
+ * data pages, or other high order pages allocated by
+ * __get_free_pages() without __GFP_COMP, which have a page_count
+ * of 0 and/or have PageSlab() set. We cannot use send_page for
+ * those, as that does get_page(); put_page(); and would cause
+ * either a VM_BUG directly, or __page_cache_release a page that
+ * would actually still be referenced by someone, leading to some
+ * obscure delayed Oops somewhere else.
+ */
+static inline bool sendpage_ok(struct page *page)
+{
+ return (!PageSlab(page) && page_count(page) >= 1);
+}
+
int kernel_sendmsg(struct socket *sock, struct msghdr *msg, struct kvec *vec,
size_t num, size_t len);
int kernel_sendmsg_locked(struct sock *sk, struct msghdr *msg,--
2.26.2
In _drbd_send_page() a page is checked by following code before sending
it by kernel_sendpage(),
(page_count(page) < 1) || PageSlab(page)
If the check is true, this page won't be send by kernel_sendpage() and
handled by sock_no_sendpage().
This kind of check is exactly what macro sendpage_ok() does, which is
introduced into include/linux/net.h to solve a similar send page issue
in nvme-tcp code.
This patch uses macro sendpage_ok() to replace the open coded checks to
page type and refcount in _drbd_send_page(), as a code cleanup.
Signed-off-by: Coly Li <redacted>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Sagi Grimberg <sagi@grimberg.me>
---
drivers/block/drbd/drbd_main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index cb687ccdbd96..55dc0c91781e 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -1553,7 +1553,7 @@ static int _drbd_send_page(struct drbd_peer_device *peer_device, struct page *pa
* put_page(); and would cause either a VM_BUG directly, or
* __page_cache_release a page that would actually still be referenced
* by someone, leading to some obscure delayed Oops somewhere else. */
- if (drbd_disable_sendpage || (page_count(page) < 1) || PageSlab(page))
+ if (drbd_disable_sendpage || !sendpage_ok(page))
return _drbd_no_send_page(peer_device, page, offset, size, msg_flags);
msg_flags |= MSG_NOSIGNAL;
--
2.26.2
Currently nvme_tcp_try_send_data() doesn't use kernel_sendpage() to
send slab pages. But for pages allocated by __get_free_pages() without
__GFP_COMP, which also have refcount as 0, they are still sent by
kernel_sendpage() to remote end, this is problematic.
The new introduced helper sendpage_ok() checks both PageSlab tag and
page_count counter, and returns true if the checking page is OK to be
sent by kernel_sendpage().
This patch fixes the page checking issue of nvme_tcp_try_send_data()
with sendpage_ok(). If sendpage_ok() returns true, send this page by
kernel_sendpage(), otherwise use sock_no_sendpage to handle this page.
Signed-off-by: Coly Li <redacted>
Cc: Chaitanya Kulkarni <redacted>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Jan Kara <jack@suse.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Mikhail Skorzhinskii <redacted>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Vlastimil Babka <redacted>
Cc: stable@vger.kernel.org
---
drivers/nvme/host/tcp.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 62fbaecdc960..902fe742762b 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -912,12 +912,11 @@ static int nvme_tcp_try_send_data(struct nvme_tcp_request *req)
else
flags |= MSG_MORE | MSG_SENDPAGE_NOTLAST;
- /* can't zcopy slab pages */
- if (unlikely(PageSlab(page))) {
- ret = sock_no_sendpage(queue->sock, page, offset, len,
+ if (sendpage_ok(page)) {
+ ret = kernel_sendpage(queue->sock, page, offset, len,
flags);
} else {
- ret = kernel_sendpage(queue->sock, page, offset, len,
+ ret = sock_no_sendpage(queue->sock, page, offset, len,
flags);
}
if (ret <= 0)--
2.26.2
Hi Coly,
I love your patch! Yet something to improve:
[auto build test ERROR on block/for-next]
[also build test ERROR on net/master net-next/master ipvs/master linus/master v5.8 next-20200814]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/0day-ci/linux/commits/Coly-Li/net-introduce-helper-sendpage_ok-in-include-linux-net-h/20200816-090533
base: https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git for-next
config: i386-randconfig-s002-20200816 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce:
# apt-get install sparse
# sparse version: v0.6.2-168-g9554805c-dirty
# save the attached .config to linux build tree
make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=i386
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <redacted>
All errors (new ones prefixed by >>):
In file included from net/core/stream.c:18:
include/linux/net.h: In function 'sendpage_ok':quoted
include/linux/net.h:301:30: error: implicit declaration of function 'page_count'; did you mean 'file_count'? [-Werror=implicit-function-declaration]
301 | return (!PageSlab(page) && page_count(page) >= 1);
| ^~~~~~~~~~
| file_count
In file included from include/linux/mm.h:27,
from include/linux/bvec.h:13,
from include/linux/skbuff.h:17,
from include/linux/tcp.h:17,
from net/core/stream.c:20:
include/linux/page_ref.h: At top level:quoted
include/linux/page_ref.h:70:19: error: static declaration of 'page_count' follows non-static declaration
70 | static inline int page_count(struct page *page)
| ^~~~~~~~~~
In file included from net/core/stream.c:18:
include/linux/net.h:301:30: note: previous implicit declaration of 'page_count' was here
301 | return (!PageSlab(page) && page_count(page) >= 1);
| ^~~~~~~~~~
cc1: some warnings being treated as errors
--
In file included from net/ipv6/ip6_fib.c:20:
include/linux/net.h: In function 'sendpage_ok':quoted
include/linux/net.h:301:30: error: implicit declaration of function 'page_count'; did you mean 'file_count'? [-Werror=implicit-function-declaration]
301 | return (!PageSlab(page) && page_count(page) >= 1);
| ^~~~~~~~~~
| file_count
In file included from include/linux/mm.h:27,
from include/linux/bvec.h:13,
from include/linux/skbuff.h:17,
from include/linux/if_ether.h:19,
from include/uapi/linux/ethtool.h:19,
from include/linux/ethtool.h:18,
from include/linux/netdevice.h:37,
from net/ipv6/ip6_fib.c:22:
include/linux/page_ref.h: At top level:quoted
include/linux/page_ref.h:70:19: error: static declaration of 'page_count' follows non-static declaration
70 | static inline int page_count(struct page *page)
| ^~~~~~~~~~
In file included from net/ipv6/ip6_fib.c:20:
include/linux/net.h:301:30: note: previous implicit declaration of 'page_count' was here
301 | return (!PageSlab(page) && page_count(page) >= 1);
| ^~~~~~~~~~
net/ipv6/ip6_fib.c: In function 'fib6_add':
net/ipv6/ip6_fib.c:1373:25: warning: variable 'pn' set but not used [-Wunused-but-set-variable]
1373 | struct fib6_node *fn, *pn = NULL;
| ^~
cc1: some warnings being treated as errors
--
In file included from net/ipv6/udp.c:24:
include/linux/net.h: In function 'sendpage_ok':quoted
include/linux/net.h:301:30: error: implicit declaration of function 'page_count'; did you mean 'file_count'? [-Werror=implicit-function-declaration]
301 | return (!PageSlab(page) && page_count(page) >= 1);
| ^~~~~~~~~~
| file_count
In file included from include/linux/mm.h:27,
from include/linux/bvec.h:13,
from include/linux/skbuff.h:17,
from include/linux/if_ether.h:19,
from include/uapi/linux/ethtool.h:19,
from include/linux/ethtool.h:18,
from include/linux/netdevice.h:37,
from net/ipv6/udp.c:26:
include/linux/page_ref.h: At top level:quoted
include/linux/page_ref.h:70:19: error: static declaration of 'page_count' follows non-static declaration
70 | static inline int page_count(struct page *page)
| ^~~~~~~~~~
In file included from net/ipv6/udp.c:24:
include/linux/net.h:301:30: note: previous implicit declaration of 'page_count' was here
301 | return (!PageSlab(page) && page_count(page) >= 1);
| ^~~~~~~~~~
net/ipv6/udp.c:1029:30: warning: no previous prototype for 'udp_v6_early_demux' [-Wmissing-prototypes]
1029 | INDIRECT_CALLABLE_SCOPE void udp_v6_early_demux(struct sk_buff *skb)
| ^~~~~~~~~~~~~~~~~~
net/ipv6/udp.c:1070:29: warning: no previous prototype for 'udpv6_rcv' [-Wmissing-prototypes]
1070 | INDIRECT_CALLABLE_SCOPE int udpv6_rcv(struct sk_buff *skb)
| ^~~~~~~~~
cc1: some warnings being treated as errors
vim +301 include/linux/net.h
283
284 #define net_get_random_once(buf, nbytes) \
285 get_random_once((buf), (nbytes))
286 #define net_get_random_once_wait(buf, nbytes) \
287 get_random_once_wait((buf), (nbytes))
288
289 /*
290 * E.g. XFS meta- & log-data is in slab pages, or bcache meta
291 * data pages, or other high order pages allocated by
292 * __get_free_pages() without __GFP_COMP, which have a page_count
293 * of 0 and/or have PageSlab() set. We cannot use send_page for
294 * those, as that does get_page(); put_page(); and would cause
295 * either a VM_BUG directly, or __page_cache_release a page that
296 * would actually still be referenced by someone, leading to some
297 * obscure delayed Oops somewhere else.
298 */
299 static inline bool sendpage_ok(struct page *page)
300 {
> 301 return (!PageSlab(page) && page_count(page) >= 1);
302 }
303
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org