This is a note to let you know that I've just added the patch titled
eventpoll: add EPOLL_URING_WAKE poll wakeup flag
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
eventpoll-add-epoll_uring_wake-poll-wakeup-flag.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 5d0d6c3d70a751ae214e471989fc729956c6fccb Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@xxxxxxxxx>
Date: Sun, 20 Nov 2022 10:10:53 -0700
Subject: eventpoll: add EPOLL_URING_WAKE poll wakeup flag
From: Jens Axboe <axboe@xxxxxxxxx>
[ Upstream commit caf1aeaffc3b09649a56769e559333ae2c4f1802 ]
We can have dependencies between epoll and io_uring. Consider an epoll
context, identified by the epfd file descriptor, and an io_uring file
descriptor identified by iofd. If we add iofd to the epfd context, and
arm a multishot poll request for epfd with iofd, then the multishot
poll request will repeatedly trigger and generate events until terminated
by CQ ring overflow. This isn't a desired behavior.
Add EPOLL_URING so that io_uring can pass it in as part of the poll wakeup
key, and io_uring can check for that to detect a potential recursive
invocation.
Cc: stable@xxxxxxxxxxxxxxx # 6.0
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/eventpoll.c | 18 ++++++++++--------
include/uapi/linux/eventpoll.h | 6 ++++++
2 files changed, 16 insertions(+), 8 deletions(-)
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -548,7 +548,8 @@ out_unlock:
*/
#ifdef CONFIG_DEBUG_LOCK_ALLOC
-static void ep_poll_safewake(struct eventpoll *ep, struct epitem *epi)
+static void ep_poll_safewake(struct eventpoll *ep, struct epitem *epi,
+ unsigned pollflags)
{
struct eventpoll *ep_src;
unsigned long flags;
@@ -579,16 +580,17 @@ static void ep_poll_safewake(struct even
}
spin_lock_irqsave_nested(&ep->poll_wait.lock, flags, nests);
ep->nests = nests + 1;
- wake_up_locked_poll(&ep->poll_wait, EPOLLIN);
+ wake_up_locked_poll(&ep->poll_wait, EPOLLIN | pollflags);
ep->nests = 0;
spin_unlock_irqrestore(&ep->poll_wait.lock, flags);
}
#else
-static void ep_poll_safewake(struct eventpoll *ep, struct epitem *epi)
+static void ep_poll_safewake(struct eventpoll *ep, struct epitem *epi,
+ unsigned pollflags)
{
- wake_up_poll(&ep->poll_wait, EPOLLIN);
+ wake_up_poll(&ep->poll_wait, EPOLLIN | pollflags);
}
#endif
@@ -815,7 +817,7 @@ static void ep_free(struct eventpoll *ep
/* We need to release all tasks waiting for these file */
if (waitqueue_active(&ep->poll_wait))
- ep_poll_safewake(ep, NULL);
+ ep_poll_safewake(ep, NULL, 0);
/*
* We need to lock this because we could be hit by
@@ -1284,7 +1286,7 @@ out_unlock:
/* We have to call this outside the lock */
if (pwake)
- ep_poll_safewake(ep, epi);
+ ep_poll_safewake(ep, epi, pollflags & EPOLL_URING_WAKE);
if (!(epi->event.events & EPOLLEXCLUSIVE))
ewake = 1;
@@ -1589,7 +1591,7 @@ static int ep_insert(struct eventpoll *e
/* We have to call this outside the lock */
if (pwake)
- ep_poll_safewake(ep, NULL);
+ ep_poll_safewake(ep, NULL, 0);
return 0;
@@ -1692,7 +1694,7 @@ static int ep_modify(struct eventpoll *e
/* We have to call this outside the lock */
if (pwake)
- ep_poll_safewake(ep, NULL);
+ ep_poll_safewake(ep, NULL, 0);
return 0;
}
--- a/include/uapi/linux/eventpoll.h
+++ b/include/uapi/linux/eventpoll.h
@@ -41,6 +41,12 @@
#define EPOLLMSG (__force __poll_t)0x00000400
#define EPOLLRDHUP (__force __poll_t)0x00002000
+/*
+ * Internal flag - wakeup generated by io_uring, used to detect recursion back
+ * into the io_uring poll handler.
+ */
+#define EPOLL_URING_WAKE ((__force __poll_t)(1U << 27))
+
/* Set exclusive wakeup mode for the target file descriptor */
#define EPOLLEXCLUSIVE ((__force __poll_t)(1U << 28))
Patches currently in stable-queue which might be from axboe@xxxxxxxxx are
queue-5.10/x86-process-setup-io_threads-more-like-normal-user-space-threads.patch
queue-5.10/powerpc-add-support-for-tif_notify_signal.patch
queue-5.10/eventfd-provide-a-eventfd_signal_mask-helper.patch
queue-5.10/fs-provide-locked-helper-variant-of-close_fd_get_file.patch
queue-5.10/relay-fix-type-mismatch-when-allocating-memory-in-re.patch
queue-5.10/eventfd-change-int-to-__u64-in-eventfd_signal-ifndef.patch
queue-5.10/io_uring-pass-in-epoll_uring_wake-for-eventfd-signaling-and-wakeups.patch
queue-5.10/blk-mq-fix-possible-memleak-when-register-hctx-faile.patch
queue-5.10/fix-handling-of-nd-depth-on-lookup_cached-failures-in-try_to_unlazy.patch
queue-5.10/net-provide-__sys_shutdown_sock-that-takes-a-socket.patch
queue-5.10/task_work-unconditionally-run-task_work-from-get_signal.patch
queue-5.10/openrisc-add-support-for-tif_notify_signal.patch
queue-5.10/signal-add-task_sigpending-helper.patch
queue-5.10/net-remove-cmsg-restriction-from-io_uring-based-send-recvmsg-calls.patch
queue-5.10/alpha-add-support-for-tif_notify_signal.patch
queue-5.10/nios32-add-support-for-tif_notify_signal.patch
queue-5.10/ia64-don-t-call-handle_signal-unless-there-s-actually-a-signal-queued.patch
queue-5.10/task_work-remove-legacy-twa_signal-path.patch
queue-5.10/revert-proc-don-t-allow-async-path-resolution-of-proc-self-components.patch
queue-5.10/m68k-add-support-for-tif_notify_signal.patch
queue-5.10/s390-add-support-for-tif_notify_signal.patch
queue-5.10/um-add-support-for-tif_notify_signal.patch
queue-5.10/tools-headers-uapi-sync-openat2.h-with-the-kernel-sources.patch
queue-5.10/kernel-provide-create_io_thread-helper.patch
queue-5.10/iov_iter-add-helper-to-save-iov_iter-state.patch
queue-5.10/arc-unbork-5.11-bootup-fix-snafu-in-_tif_notify_signal-handling.patch
queue-5.10/arch-ensure-parisc-powerpc-handle-pf_io_worker-in-copy_thread.patch
queue-5.10/csky-add-support-for-tif_notify_signal.patch
queue-5.10/arm-add-support-for-tif_notify_signal.patch
queue-5.10/kernel-stop-masking-signals-in-create_io_thread.patch
queue-5.10/fs-expose-lookup_cached-through-openat2-resolve_cached.patch
queue-5.10/task_work-add-helper-for-more-targeted-task_work-canceling.patch
queue-5.10/nds32-add-support-for-tif_notify_signal.patch
queue-5.10/signal-kill-jobctl_task_work.patch
queue-5.10/hexagon-add-support-for-tif_notify_signal.patch
queue-5.10/sh-add-support-for-tif_notify_signal.patch
queue-5.10/riscv-add-support-for-tif_notify_signal.patch
queue-5.10/h8300-add-support-for-tif_notify_signal.patch
queue-5.10/io_uring-import-5.15-stable-io_uring.patch
queue-5.10/sparc-add-support-for-tif_notify_signal.patch
queue-5.10/blktrace-fix-output-non-blktrace-event-when-blk_clas.patch
queue-5.10/eventpoll-add-epoll_uring_wake-poll-wakeup-flag.patch
queue-5.10/parisc-add-support-for-tif_notify_signal.patch
queue-5.10/entry-add-support-for-tif_notify_signal.patch
queue-5.10/x86-wire-up-tif_notify_signal.patch
queue-5.10/task_work-use-tif_notify_signal-if-available.patch
queue-5.10/drbd-fix-an-invalid-memory-access-caused-by-incorrec.patch
queue-5.10/kernel-don-t-call-do_exit-for-pf_io_worker-threads.patch
queue-5.10/kernel-allow-fork-with-tif_notify_signal-pending.patch
queue-5.10/pata_ipx4xx_cf-fix-unsigned-comparison-with-less-tha.patch
queue-5.10/mips-add-support-for-tif_notify_signal.patch
queue-5.10/xtensa-add-support-for-tif_notify_signal.patch
queue-5.10/c6x-add-support-for-tif_notify_signal.patch
queue-5.10/microblaze-add-support-for-tif_notify_signal.patch
queue-5.10/net-add-accept-helper-not-installing-fd.patch
queue-5.10/ia64-add-support-for-tif_notify_signal.patch
queue-5.10/arm64-add-support-for-tif_notify_signal.patch
queue-5.10/arc-add-support-for-tif_notify_signal.patch
queue-5.10/revert-proc-don-t-allow-async-path-resolution-of-proc-thread-self-components.patch
queue-5.10/fs-make-do_renameat2-take-struct-filename.patch
queue-5.10/kernel-remove-checking-for-tif_notify_signal.patch
queue-5.10/arch-setup-pf_io_worker-threads-like-pf_kthread.patch
queue-5.10/nvme-pci-fix-mempool-alloc-size.patch
queue-5.10/fs-add-support-for-lookup_cached.patch
