From patchwork Tue Aug 18 13:12:22 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Coly Li X-Patchwork-Id: 11720793 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id CF0CA1575 for ; Tue, 18 Aug 2020 13:13:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BDB4B20706 for ; Tue, 18 Aug 2020 13:13:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726688AbgHRNNO (ORCPT ); Tue, 18 Aug 2020 09:13:14 -0400 Received: from mx2.suse.de ([195.135.220.15]:33284 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726145AbgHRNNN (ORCPT ); Tue, 18 Aug 2020 09:13:13 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id DC6E4B15D; Tue, 18 Aug 2020 13:13:36 +0000 (UTC) From: Coly Li To: linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, netdev@vger.kernel.org, open-iscsi@googlegroups.com, linux-scsi@vger.kernel.org, ceph-devel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Coly Li , Chaitanya Kulkarni , Christoph Hellwig , Hannes Reinecke , Jan Kara , Jens Axboe , Mikhail Skorzhinskii , Philipp Reisner , Sagi Grimberg , Vlastimil Babka , stable@vger.kernel.org Subject: [PATCH v7 1/6] net: introduce helper sendpage_ok() in include/linux/net.h Date: Tue, 18 Aug 2020 21:12:22 +0800 Message-Id: <20200818131227.37020-2-colyli@suse.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200818131227.37020-1-colyli@suse.de> References: <20200818131227.37020-1-colyli@suse.de> MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 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 Cc: Chaitanya Kulkarni Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: Jan Kara Cc: Jens Axboe Cc: Mikhail Skorzhinskii Cc: Philipp Reisner Cc: Sagi Grimberg Cc: Vlastimil Babka Cc: stable@vger.kernel.org Signed-off-by: Christoph Hellwig --- include/linux/net.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/include/linux/net.h b/include/linux/net.h index d48ff1180879..05db8690f67e 100644 --- a/include/linux/net.h +++ b/include/linux/net.h @@ -21,6 +21,7 @@ #include #include #include +#include #include #include @@ -286,6 +287,21 @@ 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, From patchwork Tue Aug 18 13:12:23 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Coly Li X-Patchwork-Id: 11720799 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 89D721575 for ; Tue, 18 Aug 2020 13:13:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6CB07207DE for ; Tue, 18 Aug 2020 13:13:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726740AbgHRNN0 (ORCPT ); Tue, 18 Aug 2020 09:13:26 -0400 Received: from mx2.suse.de ([195.135.220.15]:33412 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726731AbgHRNNZ (ORCPT ); Tue, 18 Aug 2020 09:13:25 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 2008BB167; Tue, 18 Aug 2020 13:13:44 +0000 (UTC) From: Coly Li To: linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, netdev@vger.kernel.org, open-iscsi@googlegroups.com, linux-scsi@vger.kernel.org, ceph-devel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Coly Li , Chaitanya Kulkarni , Christoph Hellwig , Hannes Reinecke , Jan Kara , Jens Axboe , Mikhail Skorzhinskii , Philipp Reisner , Sagi Grimberg , Vlastimil Babka , stable@vger.kernel.org Subject: [PATCH v7 2/6] nvme-tcp: check page by sendpage_ok() before calling kernel_sendpage() Date: Tue, 18 Aug 2020 21:12:23 +0800 Message-Id: <20200818131227.37020-3-colyli@suse.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200818131227.37020-1-colyli@suse.de> References: <20200818131227.37020-1-colyli@suse.de> MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 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 Cc: Chaitanya Kulkarni Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: Jan Kara Cc: Jens Axboe Cc: Mikhail Skorzhinskii Cc: Philipp Reisner Cc: Sagi Grimberg Cc: Vlastimil Babka 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) From patchwork Tue Aug 18 13:12:24 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Coly Li X-Patchwork-Id: 11720825 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 80B2B1575 for ; Tue, 18 Aug 2020 13:14:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6941A2076D for ; Tue, 18 Aug 2020 13:14:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726760AbgHRNN0 (ORCPT ); Tue, 18 Aug 2020 09:13:26 -0400 Received: from mx2.suse.de ([195.135.220.15]:33482 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726681AbgHRNNZ (ORCPT ); Tue, 18 Aug 2020 09:13:25 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id EE92EB178; Tue, 18 Aug 2020 13:13:48 +0000 (UTC) From: Coly Li To: linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, netdev@vger.kernel.org, open-iscsi@googlegroups.com, linux-scsi@vger.kernel.org, ceph-devel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Coly Li , Eric Dumazet , Vasily Averin , "David S . Miller" , stable@vger.kernel.org Subject: [PATCH v7 3/6] tcp: use sendpage_ok() to detect misused .sendpage Date: Tue, 18 Aug 2020 21:12:24 +0800 Message-Id: <20200818131227.37020-4-colyli@suse.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200818131227.37020-1-colyli@suse.de> References: <20200818131227.37020-1-colyli@suse.de> MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org commit a10674bf2406 ("tcp: detecting the misuse of .sendpage for Slab objects") adds the checks for Slab pages, but the pages don't have page_count are still missing from the check. Network layer's sendpage method is not designed to send page_count 0 pages neither, therefore both PageSlab() and page_count() should be both checked for the sending page. This is exactly what sendpage_ok() does. This patch uses sendpage_ok() in do_tcp_sendpages() to detect misused .sendpage, to make the code more robust. Fixes: a10674bf2406 ("tcp: detecting the misuse of .sendpage for Slab objects") Suggested-by: Eric Dumazet Signed-off-by: Coly Li Cc: Vasily Averin Cc: David S. Miller Cc: stable@vger.kernel.org --- net/ipv4/tcp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 31f3b858db81..2135ee7c806d 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -970,7 +970,8 @@ ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset, long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT); if (IS_ENABLED(CONFIG_DEBUG_VM) && - WARN_ONCE(PageSlab(page), "page must not be a Slab one")) + WARN_ONCE(!sendpage_ok(page), + "page must not be a Slab one and have page_count > 0")) return -EINVAL; /* Wait for a connection to finish. One exception is TCP Fast Open From patchwork Tue Aug 18 13:12:25 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Coly Li X-Patchwork-Id: 11720817 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C847D138C for ; Tue, 18 Aug 2020 13:14:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ADB262076D for ; Tue, 18 Aug 2020 13:14:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726843AbgHRNNh (ORCPT ); Tue, 18 Aug 2020 09:13:37 -0400 Received: from mx2.suse.de ([195.135.220.15]:33534 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726794AbgHRNN3 (ORCPT ); Tue, 18 Aug 2020 09:13:29 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 427FFB17A; Tue, 18 Aug 2020 13:13:53 +0000 (UTC) From: Coly Li To: linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, netdev@vger.kernel.org, open-iscsi@googlegroups.com, linux-scsi@vger.kernel.org, ceph-devel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Coly Li , Philipp Reisner , Sagi Grimberg Subject: [PATCH v7 4/6] drbd: code cleanup by using sendpage_ok() to check page for kernel_sendpage() Date: Tue, 18 Aug 2020 21:12:25 +0800 Message-Id: <20200818131227.37020-5-colyli@suse.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200818131227.37020-1-colyli@suse.de> References: <20200818131227.37020-1-colyli@suse.de> MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 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 Cc: Philipp Reisner Cc: Sagi Grimberg --- 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; From patchwork Tue Aug 18 13:12:26 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Coly Li X-Patchwork-Id: 11720815 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 05645138C for ; Tue, 18 Aug 2020 13:14:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E1ABB20786 for ; Tue, 18 Aug 2020 13:14:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726848AbgHRNNh (ORCPT ); Tue, 18 Aug 2020 09:13:37 -0400 Received: from mx2.suse.de ([195.135.220.15]:33628 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726829AbgHRNNf (ORCPT ); Tue, 18 Aug 2020 09:13:35 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 929A8B17F; Tue, 18 Aug 2020 13:13:59 +0000 (UTC) From: Coly Li To: linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, netdev@vger.kernel.org, open-iscsi@googlegroups.com, linux-scsi@vger.kernel.org, ceph-devel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Coly Li , Vasily Averin , Cong Wang , Mike Christie , Lee Duncan , Chris Leech , Christoph Hellwig , Hannes Reinecke Subject: [PATCH v7 5/6] scsi: libiscsi: use sendpage_ok() in iscsi_tcp_segment_map() Date: Tue, 18 Aug 2020 21:12:26 +0800 Message-Id: <20200818131227.37020-6-colyli@suse.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200818131227.37020-1-colyli@suse.de> References: <20200818131227.37020-1-colyli@suse.de> MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org In iscsci driver, iscsi_tcp_segment_map() uses the following code to check whether the page should or not be handled by sendpage: if (!recv && page_count(sg_page(sg)) >= 1 && !PageSlab(sg_page(sg))) The "page_count(sg_page(sg)) >= 1 && !PageSlab(sg_page(sg)" part is to make sure the page can be sent to network layer's zero copy path. This part is exactly what sendpage_ok() does. This patch uses use sendpage_ok() in iscsi_tcp_segment_map() to replace the original open coded checks. Signed-off-by: Coly Li Cc: Vasily Averin Cc: Cong Wang Cc: Mike Christie Cc: Lee Duncan Cc: Chris Leech Cc: Christoph Hellwig Cc: Hannes Reinecke --- drivers/scsi/libiscsi_tcp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/scsi/libiscsi_tcp.c b/drivers/scsi/libiscsi_tcp.c index 6ef93c7af954..31cd8487c16e 100644 --- a/drivers/scsi/libiscsi_tcp.c +++ b/drivers/scsi/libiscsi_tcp.c @@ -128,7 +128,7 @@ static void iscsi_tcp_segment_map(struct iscsi_segment *segment, int recv) * coalescing neighboring slab objects into a single frag which * triggers one of hardened usercopy checks. */ - if (!recv && page_count(sg_page(sg)) >= 1 && !PageSlab(sg_page(sg))) + if (!recv && sendpage_ok(sg_page(sg))) return; if (recv) { From patchwork Tue Aug 18 13:12:27 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Coly Li X-Patchwork-Id: 11720807 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 292751575 for ; Tue, 18 Aug 2020 13:14:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 195C42076D for ; Tue, 18 Aug 2020 13:14:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726889AbgHRNNy (ORCPT ); Tue, 18 Aug 2020 09:13:54 -0400 Received: from mx2.suse.de ([195.135.220.15]:33698 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726884AbgHRNNk (ORCPT ); Tue, 18 Aug 2020 09:13:40 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 811D9B178; Tue, 18 Aug 2020 13:14:04 +0000 (UTC) From: Coly Li To: linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, netdev@vger.kernel.org, open-iscsi@googlegroups.com, linux-scsi@vger.kernel.org, ceph-devel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Coly Li , Ilya Dryomov , Jeff Layton Subject: [PATCH v7 6/6] libceph: use sendpage_ok() in ceph_tcp_sendpage() Date: Tue, 18 Aug 2020 21:12:27 +0800 Message-Id: <20200818131227.37020-7-colyli@suse.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200818131227.37020-1-colyli@suse.de> References: <20200818131227.37020-1-colyli@suse.de> MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org In libceph, ceph_tcp_sendpage() does the following checks before handle the page by network layer's zero copy sendpage method, if (page_count(page) >= 1 && !PageSlab(page)) This check is exactly what sendpage_ok() does. This patch replace the open coded checks by sendpage_ok() as a code cleanup. Signed-off-by: Coly Li Cc: Ilya Dryomov Cc: Jeff Layton --- net/ceph/messenger.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c index 27d6ab11f9ee..6a349da7f013 100644 --- a/net/ceph/messenger.c +++ b/net/ceph/messenger.c @@ -575,7 +575,7 @@ static int ceph_tcp_sendpage(struct socket *sock, struct page *page, * coalescing neighboring slab objects into a single frag which * triggers one of hardened usercopy checks. */ - if (page_count(page) >= 1 && !PageSlab(page)) + if (sendpage_ok(page)) sendpage = sock->ops->sendpage; else sendpage = sock_no_sendpage;