Status from old attempts to solve same nature issues: ----
Older (2018) merge request from @raharper: https://github.com/koverstreet/bcache-tools/pull/1 addressing the fact that kernel uevents would not always emit CACHED_UUID parameters, making udev to delete (whenever that happens) /dev/bcache/{by-uuid,by-label} symlinks. This last MR pointed to previous related bugs: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=890446 https://bugs.launchpad.net/curtin/+bug/1728742 And to an upstream kernel patch: https://lore.kernel.org/patchwork/patch/921298/ to https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1729145 that wasn't accepted upstream. Even not being accepted upstream, the SRU was attempted: LP: #1729145 https://lists.ubuntu.com/archives/kernel-team/2017-December/088680.html https://lists.ubuntu.com/archives/kernel-team/2017-December/088679.html Both were NACKED. Attempted again: https://lists.ubuntu.com/archives/kernel-team/2017-December/088682.html https://lists.ubuntu.com/archives/kernel-team/2017-December/088683.html NACKED again. And a v2 was sent: https://lists.ubuntu.com/archives/kernel-team/2017-December/088751.html https://lists.ubuntu.com/archives/kernel-team/2017-December/088750.html https://lists.ubuntu.com/archives/kernel-team/2017-December/088749.html and acked in January 2018 by Coling: https://lists.ubuntu.com/archives/kernel-team/2018-January/089492.html but not upstreamed. BIONIC contains the fix: commit ed9333e1b583 Author: Ryan Harper <ryan.har...@canonical.com> Date: Mon Dec 11 12:12:01 2017 UBUNTU: SAUCE: (no-up) bcache: decouple emitting a cached_dev CHANGE uevent BugLink: http://bugs.launchpad.net/bugs/1729145 - decouple emitting a cached_dev CHANGE uevent which includes dev.uuid and dev.label from bch_cached_dev_run() which only happens when a bcacheX device is bound to the actual backing block device (bcache0 -> vdb) - update bch_cached_dev_run() to invoke bch_cached_dev_emit_change() as needed; no functional code path changes here - Modify register_bcache to detect a re-registering of a bcache cached_dev, and in that case call bcache_cached_dev_emit_change() to Signed-off-by: Ryan Harper <ryan.har...@canonical.com> Signed-off-by: Joseph Salisbury <joseph.salisb...@canonical.com> Acked-by: Colin Ian King <colin.k...@canonical.com> Acked-by: Stefan Bader <stefan.ba...@canonical.com> Signed-off-by: Khalid Elmously <khalid.elmou...@canonical.com> [ saf: fix incorrect indentation ] Signed-off-by: Seth Forshee <seth.fors...@canonical.com> FOCAL contains the fix: commit 67553dcd7905 Author: Ryan Harper <ryan.har...@canonical.com> Date: Mon Dec 11 12:12:01 2017 UBUNTU: SAUCE: (no-up) bcache: decouple emitting a cached_dev CHANGE uevent GROOVY contains the fix: commit 67553dcd7905 Author: Ryan Harper <ryan.har...@canonical.com> Date: Mon Dec 11 12:12:01 2017 UBUNTU: SAUCE: (no-up) bcache: decouple emitting a cached_dev CHANGE uevent ---- So, the kernel patch wasn't accepted, nor bcache-tools patch by @raharper, the bcache-export-cached. ---- New Upstream summary from @raharper: https://github.com/systemd/systemd/pull/16317#issuecomment-655647313 in the upstream merge request made by @rbalint. ** Bug watch added: Debian Bug tracker #890446 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=890446 -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1805256 Title: qemu-img hangs on rcu_call_ready_event logic in Aarch64 when converting images Status in kunpeng920: Triaged Status in kunpeng920 ubuntu-18.04 series: Triaged Status in kunpeng920 ubuntu-18.04-hwe series: Triaged Status in kunpeng920 ubuntu-19.10 series: Fix Released Status in kunpeng920 ubuntu-20.04 series: Fix Released Status in kunpeng920 upstream-kernel series: Invalid Status in QEMU: Fix Released Status in qemu package in Ubuntu: Fix Released Status in qemu source package in Bionic: In Progress Status in qemu source package in Eoan: Fix Released Status in qemu source package in Focal: Fix Released Bug description: [Impact] * QEMU locking primitives might face a race condition in QEMU Async I/O bottom halves scheduling. This leads to a dead lock making either QEMU or one of its tools to hang indefinitely. [Test Case] * qemu-img convert -f qcow2 -O qcow2 ./disk01.qcow2 ./output.qcow2 Hangs indefinitely approximately 30% of the runs in Aarch64. [Regression Potential] * This is a change to a core part of QEMU: The AIO scheduling. It works like a "kernel" scheduler, whereas kernel schedules OS tasks, the QEMU AIO code is responsible to schedule QEMU coroutines or event listeners callbacks. * There was a long discussion upstream about primitives and Aarch64. After quite sometime Paolo released this patch and it solves the issue. Tested platforms were: amd64 and aarch64 based on his commit log. * Christian suggests that this fix stay little longer in -proposed to make sure it won't cause any regressions. * dannf suggests we also check for performance regressions; e.g. how long it takes to convert a cloud image on high-core systems. [Other Info] * Original Description bellow: Command: qemu-img convert -f qcow2 -O qcow2 ./disk01.qcow2 ./output.qcow2 Hangs indefinitely approximately 30% of the runs. ---- Workaround: qemu-img convert -m 1 -f qcow2 -O qcow2 ./disk01.qcow2 ./output.qcow2 Run "qemu-img convert" with "a single coroutine" to avoid this issue. ---- (gdb) thread 1 ... (gdb) bt #0 0x0000ffffbf1ad81c in __GI_ppoll #1 0x0000aaaaaabcf73c in ppoll #2 qemu_poll_ns #3 0x0000aaaaaabd0764 in os_host_main_loop_wait #4 main_loop_wait ... (gdb) thread 2 ... (gdb) bt #0 syscall () #1 0x0000aaaaaabd41cc in qemu_futex_wait #2 qemu_event_wait (ev=ev@entry=0xaaaaaac86ce8 <rcu_call_ready_event>) #3 0x0000aaaaaabed05c in call_rcu_thread #4 0x0000aaaaaabd34c8 in qemu_thread_start #5 0x0000ffffbf25c880 in start_thread #6 0x0000ffffbf1b6b9c in thread_start () (gdb) thread 3 ... (gdb) bt #0 0x0000ffffbf11aa20 in __GI___sigtimedwait #1 0x0000ffffbf2671b4 in __sigwait #2 0x0000aaaaaabd1ddc in sigwait_compat #3 0x0000aaaaaabd34c8 in qemu_thread_start #4 0x0000ffffbf25c880 in start_thread #5 0x0000ffffbf1b6b9c in thread_start ---- (gdb) run Starting program: /usr/bin/qemu-img convert -f qcow2 -O qcow2 ./disk01.ext4.qcow2 ./output.qcow2 [New Thread 0xffffbec5ad90 (LWP 72839)] [New Thread 0xffffbe459d90 (LWP 72840)] [New Thread 0xffffbdb57d90 (LWP 72841)] [New Thread 0xffffacac9d90 (LWP 72859)] [New Thread 0xffffa7ffed90 (LWP 72860)] [New Thread 0xffffa77fdd90 (LWP 72861)] [New Thread 0xffffa6ffcd90 (LWP 72862)] [New Thread 0xffffa67fbd90 (LWP 72863)] [New Thread 0xffffa5ffad90 (LWP 72864)] [Thread 0xffffa5ffad90 (LWP 72864) exited] [Thread 0xffffa6ffcd90 (LWP 72862) exited] [Thread 0xffffa77fdd90 (LWP 72861) exited] [Thread 0xffffbdb57d90 (LWP 72841) exited] [Thread 0xffffa67fbd90 (LWP 72863) exited] [Thread 0xffffacac9d90 (LWP 72859) exited] [Thread 0xffffa7ffed90 (LWP 72860) exited] <HUNG w/ 3 threads in the stack trace showed before> """ All the tasks left are blocked in a system call, so no task left to call qemu_futex_wake() to unblock thread #2 (in futex()), which would unblock thread #1 (doing poll() in a pipe with thread #2). Those 7 threads exit before disk conversion is complete (sometimes in the beginning, sometimes at the end). ---- On the HiSilicon D06 system - a 96 core NUMA arm64 box - qemu-img frequently hangs (~50% of the time) with this command: qemu-img convert -f qcow2 -O qcow2 /tmp/cloudimg /tmp/cloudimg2 Where "cloudimg" is a standard qcow2 Ubuntu cloud image. This qcow2->qcow2 conversion happens to be something uvtool does every time it fetches images. Once hung, attaching gdb gives the following backtrace: (gdb) bt #0 0x0000ffffae4f8154 in __GI_ppoll (fds=0xaaaae8a67dc0, nfds=187650274213760, timeout=<optimized out>, timeout@entry=0x0, sigmask=0xffffc123b950) at ../sysdeps/unix/sysv/linux/ppoll.c:39 #1 0x0000aaaabbefaf00 in ppoll (__ss=0x0, __timeout=0x0, __nfds=<optimized out>, __fds=<optimized out>) at /usr/include/aarch64-linux-gnu/bits/poll2.h:77 #2 qemu_poll_ns (fds=<optimized out>, nfds=<optimized out>, timeout=timeout@entry=-1) at util/qemu-timer.c:322 #3 0x0000aaaabbefbf80 in os_host_main_loop_wait (timeout=-1) at util/main-loop.c:233 #4 main_loop_wait (nonblocking=<optimized out>) at util/main-loop.c:497 #5 0x0000aaaabbe2aa30 in convert_do_copy (s=0xffffc123bb58) at qemu-img.c:1980 #6 img_convert (argc=<optimized out>, argv=<optimized out>) at qemu-img.c:2456 #7 0x0000aaaabbe2333c in main (argc=7, argv=<optimized out>) at qemu-img.c:4975 Reproduced w/ latest QEMU git (@ 53744e0a182) To manage notifications about this bug go to: https://bugs.launchpad.net/kunpeng920/+bug/1805256/+subscriptions
