This is a note to let you know that I've just added the patch titled task_work: unconditionally run task_work from get_signal() 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: task_work-unconditionally-run-task_work-from-get_signal.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 0f315fd4143c1591a7f902fa08b71b83764f4fa0 Mon Sep 17 00:00:00 2001 From: Jens Axboe <axboe@xxxxxxxxx> Date: Tue, 5 Jan 2021 11:32:43 -0700 Subject: task_work: unconditionally run task_work from get_signal() From: Jens Axboe <axboe@xxxxxxxxx> [ Upstream commit 35d0b389f3b23439ad15b610d6e43fc72fc75779 ] Song reported a boot regression in a kvm image with 5.11-rc, and bisected it down to the below patch. Debugging this issue, turns out that the boot stalled when a task is waiting on a pipe being released. As we no longer run task_work from get_signal() unless it's queued with TWA_SIGNAL, the task goes idle without running the task_work. This prevents ->release() from being called on the pipe, which another boot task is waiting on. For now, re-instate the unconditional task_work run from get_signal(). For 5.12, we'll collapse TWA_RESUME and TWA_SIGNAL, as it no longer makes sense to have a distinction between the two. This will turn task_work notification into a simple boolean, whether to notify or not. Fixes: 98b89b649fce ("signal: kill JOBCTL_TASK_WORK") Reported-by: Song Liu <songliubraving@xxxxxx> Tested-by: John Stultz <john.stultz@xxxxxxxxxx> Tested-by: Douglas Anderson <dianders@xxxxxxxxxxxx> Tested-by: Sedat Dilek <sedat.dilek@xxxxxxxxx> # LLVM/Clang version 11.0.1 Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/signal.c | 3 +++ 1 file changed, 3 insertions(+) --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2520,6 +2520,9 @@ bool get_signal(struct ksignal *ksig) struct signal_struct *signal = current->signal; int signr; + if (unlikely(current->task_works)) + task_work_run(); + /* * For non-generic architectures, check for TIF_NOTIFY_SIGNAL so * that the arch handlers don't all have to do it. If we get here 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