Files
linux/include/linux
Kuniyuki Iwashima cd720fad8b pipe: make poll_usage boolean and annotate its access
commit f485922d8f upstream.

Patch series "Fix data-races around epoll reported by KCSAN."

This series suppresses a false positive KCSAN's message and fixes a real
data-race.


This patch (of 2):

pipe_poll() runs locklessly and assigns 1 to poll_usage.  Once poll_usage
is set to 1, it never changes in other places.  However, concurrent writes
of a value trigger KCSAN, so let's make KCSAN happy.

BUG: KCSAN: data-race in pipe_poll / pipe_poll

write to 0xffff8880042f6678 of 4 bytes by task 174 on cpu 3:
 pipe_poll (fs/pipe.c:656)
 ep_item_poll.isra.0 (./include/linux/poll.h:88 fs/eventpoll.c:853)
 do_epoll_wait (fs/eventpoll.c:1692 fs/eventpoll.c:1806 fs/eventpoll.c:2234)
 __x64_sys_epoll_wait (fs/eventpoll.c:2246 fs/eventpoll.c:2241 fs/eventpoll.c:2241)
 do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
 entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:113)

write to 0xffff8880042f6678 of 4 bytes by task 177 on cpu 1:
 pipe_poll (fs/pipe.c:656)
 ep_item_poll.isra.0 (./include/linux/poll.h:88 fs/eventpoll.c:853)
 do_epoll_wait (fs/eventpoll.c:1692 fs/eventpoll.c:1806 fs/eventpoll.c:2234)
 __x64_sys_epoll_wait (fs/eventpoll.c:2246 fs/eventpoll.c:2241 fs/eventpoll.c:2241)
 do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
 entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:113)

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 177 Comm: epoll_race Not tainted 5.17.0-58927-gf443e374ae13 #6
Hardware name: Red Hat KVM, BIOS 1.11.0-2.amzn2 04/01/2014

Link: https://lkml.kernel.org/r/20220322002653.33865-1-kuniyu@amazon.co.jp
Link: https://lkml.kernel.org/r/20220322002653.33865-2-kuniyu@amazon.co.jp
Fixes: 3b844826b6 ("pipe: avoid unnecessary EPOLLET wakeups under normal loads")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Cc: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Kuniyuki Iwashima <kuni1840@gmail.com>
Cc: "Soheil Hassas Yeganeh" <soheil@google.com>
Cc: "Sridhar Samudrala" <sridhar.samudrala@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-06-06 08:42:41 +02:00
..
2019-12-11 09:12:38 +01:00
2019-11-12 11:43:29 -05:00
2020-06-25 22:25:13 -07:00
2020-06-16 14:19:57 +02:00
2020-05-24 20:48:11 +02:00
2020-09-21 15:00:40 -07:00
2020-10-02 15:00:49 -07:00
2020-10-16 17:21:51 +02:00
2019-10-09 19:33:43 -07:00
2020-03-09 11:12:19 +01:00
2019-12-03 11:20:37 +01:00
2020-06-16 19:25:20 +02:00
2020-08-12 20:42:08 +02:00
2020-06-17 00:07:38 +02:00
2021-11-26 10:39:22 +01:00
2020-03-06 11:06:15 +01:00
2020-07-24 17:12:41 -07:00
2020-08-04 21:02:38 -04:00
2019-10-04 12:31:46 -07:00
2019-10-15 13:34:25 +02:00
2020-09-16 08:54:53 -05:00
2022-04-13 21:00:56 +02:00
2020-05-18 10:30:21 +01:00
2020-08-26 12:41:56 +02:00
2020-11-19 22:38:29 -05:00
2020-10-13 18:38:32 -07:00
2019-12-04 19:44:14 -08:00
2020-06-02 15:15:46 +01:00
2019-12-11 09:12:38 +01:00
2021-03-04 11:37:59 +01:00
2020-09-04 09:25:20 -07:00
2021-02-07 15:37:17 +01:00
2021-11-18 14:03:37 +01:00
2020-05-08 18:18:11 +01:00
2020-05-08 00:12:42 +02:00
2020-05-28 10:31:09 +02:00
2021-09-15 09:50:41 +02:00
2020-03-06 11:56:59 +01:00
2020-09-04 12:46:07 +01:00
2021-06-30 08:47:26 -04:00
2020-08-27 16:06:47 -04:00
2019-08-14 15:30:35 +02:00
2019-11-14 19:06:47 -08:00
2020-10-07 14:28:39 -04:00
2020-05-09 13:57:12 +02:00
2020-07-01 10:49:02 +02:00
2021-09-03 10:09:21 +02:00
2020-07-23 17:34:18 +10:00
2020-05-15 13:51:28 -07:00
2020-08-31 12:52:33 -07:00
2019-07-16 19:23:25 -07:00
2021-03-30 14:32:05 +02:00
2020-10-18 09:27:10 -07:00
2020-05-09 13:57:12 +02:00
2020-08-18 17:06:15 +02:00
2020-08-07 11:33:24 -07:00
2021-08-04 12:46:44 +02:00
2020-09-26 22:55:05 -04:00
2021-05-07 11:04:32 +02:00
2021-05-14 09:50:18 +02:00
2021-05-14 09:50:18 +02:00
2021-05-14 09:50:31 +02:00
2020-07-04 09:35:36 -05:00
2020-09-10 14:03:31 -07:00
2020-08-01 11:28:17 +02:00
2020-04-01 12:06:26 -04:00
2020-10-05 13:21:49 +02:00
2021-12-14 11:32:39 +01:00