Hi, Since the following commit https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git/commit/?h=for-5.5/disk-revalidate&id=6917d0689993f46d97d40dd66c601d0fd5b1dbdd until now(v5.6-rc4), If we start udisksd service of systemd(v244), systemd-udevd will scan /dev/hdc (the cdrom device created by default in qemu(v4.2.0)). systemd-udevd will endlessly run and cause OOM. It works well by reverting the following series of commits. 979c690d block: move clearing bd_invalidated into check_disk_size_change f0b870d block: remove (__)blkdev_reread_part as an exported API 142fe8f block: fix bdev_disk_changed for non-partitioned devices a1548b6 block: move rescan_partitions to fs/block_dev.c 6917d06 block: merge invalidate_partitions into rescan_partitions I found the number of some block events increase thousands per second. root@qemux86:~# perf top -e block:* 9 block:block_touch_buffer 2 block:block_dirty_buffer 0 block:block_rq_requeue 307K block:block_rq_complete 174K block:block_rq_insert 174K block:block_rq_issue 0 block:block_bio_bounce 0 block:block_bio_complete 2 block:block_bio_backmerge 0 block:block_bio_frontmerge 9 block:block_bio_queue 7 block:block_getrq 0 block:block_sleeprq 4 block:block_plug 4 block:block_unplug 0 block:block_split 0 block:block_bio_remap 0 block:block_rq_remap Here is the strace log from systemd-udevd. It repeats the following actions endlessly. epoll_wait(3, [{EPOLLIN, {u32=6274288, u64=6274288}}], 2, -1) = 1 clock_gettime64(CLOCK_REALTIME, {tv_sec=1582858384, tv_nsec=264944457}) = 0 clock_gettime64(CLOCK_MONOTONIC, {tv_sec=146, tv_nsec=493809949}) = 0 clock_gettime64(CLOCK_BOOTTIME, {tv_sec=146, tv_nsec=502760142}) = 0 recvmsg(14, {msg_name={sa_family=AF_NETLINK, nl_pid=-206275536, nl_groups=00000000}, msg_namelen=128->12, msg_iov=[{iov_base={{len=1969383786 getrandom("\x05\xca\xeb\xf4\x3f\x01\xb8\x0f\x7c\x89\xf9\x4b\x46\x73\x9b\xd5", 16, GRND_NONBLOCK) = 16 clock_gettime64(CLOCK_MONOTONIC, {tv_sec=146, tv_nsec=613235420}) = 0 openat(AT_FDCWD, "/dev/hdc", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC) = 6 flock(6, LOCK_SH|LOCK_NB) = 0 openat(AT_FDCWD, "/sys/devices/pci0000:00/0000:00:01.1/ide1/1.0/block/hdc/uevent", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = 15 fstat64(15, {st_mode=S_IFREG|0644, st_size=4096, ...}) = 0 fstat64(15, {st_mode=S_IFREG|0644, st_size=4096, ...}) = 0 read(15, "MAJOR=22\nMINOR=0\nDEVNAME=hdc\nDEV"..., 4096) = 42 read(15, "", 4096) = 0 close(15) = 0 openat(AT_FDCWD, "/run/udev/data/b22:0", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = 15 fstat64(15, {st_mode=S_IFREG|0644, st_size=34, ...}) = 0 fstat64(15, {st_mode=S_IFREG|0644, st_size=34, ...}) = 0 read(15, "I:4680519\nE:ID_FS_TYPE=\nG:system"..., 4096) = 34 read(15, "", 4096) = 0 close(15) = 0 getrandom("\x22\xda\x6d\x9d\x97\x44\xcc\x2d\x82\x52\x00\xb4\x7b\x75\x8d\x6a", 16, GRND_NONBLOCK) = 16 openat(AT_FDCWD, "/proc/cmdline", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = 15 fstat64(15, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0 read(15, "root=/dev/vda rw console=ttyS0 "..., 1024) = 118 ioctl(15, TCGETS, 0xbfb8b7ec) = -1 ENOTTY (Inappropriate ioctl for device) read(15, "", 1024) = 0 close(15) = 0 openat(AT_FDCWD, "/proc/cmdline", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = 15 fstat64(15, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0 read(15, "root=/dev/vda rw console=ttyS0 "..., 1024) = 118 ioctl(15, TCGETS, 0xbfb8b7ec) = -1 ENOTTY (Inappropriate ioctl for device) read(15, "", 1024) = 0 close(15) = 0 openat(AT_FDCWD, "/", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 openat(15, "sys", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 16 fstat64(16, {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0 close(15) = 0 openat(16, "devices", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 fstat64(15, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(16) = 0 openat(15, "pci0000:00", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 16 fstat64(16, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(15) = 0 openat(16, "0000:00:01.1", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 fstat64(15, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(16) = 0 openat(15, "ide1", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 16 fstat64(16, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(15) = 0 openat(16, "1.0", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 fstat64(15, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(16) = 0 openat(15, "block", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 16 fstat64(16, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(15) = 0 close(16) = 0 access("/sys/devices/pci0000:00/0000:00:01.1/ide1/1.0/block/uevent", F_OK) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 openat(15, "sys", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 16 fstat64(16, {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0 close(15) = 0 openat(16, "devices", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 fstat64(15, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(16) = 0 openat(15, "pci0000:00", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 16 fstat64(16, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(15) = 0 openat(16, "0000:00:01.1", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 fstat64(15, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(16) = 0 openat(15, "ide1", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 16 fstat64(16, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(15) = 0 openat(16, "1.0", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 fstat64(15, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(16) = 0 close(15) = 0 access("/sys/devices/pci0000:00/0000:00:01.1/ide1/1.0/uevent", F_OK) = 0 openat(AT_FDCWD, "/sys/devices/pci0000:00/0000:00:01.1/ide1/1.0/uevent", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = 15 fstat64(15, {st_mode=S_IFREG|0644, st_size=4096, ...}) = 0 fstat64(15, {st_mode=S_IFREG|0644, st_size=4096, ...}) = 0 read(15, "DRIVER=ide-cdrom\nMEDIA=cdrom\nDRI"..., 4096) = 64 read(15, "", 4096) = 0 close(15) = 0 readlinkat(AT_FDCWD, "/sys/devices/pci0000:00/0000:00:01.1/ide1/1.0/subsystem", "../../../../../bus/ide", 4096) = 22 openat(AT_FDCWD, "/run/udev/data/+ide:1.0", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/run/udev/data/+ide:1.0", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/run/udev/data/+ide:1.0", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/run/udev/data/+ide:1.0", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/run/udev/data/+ide:1.0", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/run/udev/data/+ide:1.0", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/run/udev/data/+ide:1.0", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 openat(15, "sys", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 16 fstat64(16, {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0 close(15) = 0 openat(16, "devices", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 fstat64(15, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(16) = 0 openat(15, "pci0000:00", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 16 fstat64(16, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(15) = 0 openat(16, "0000:00:01.1", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 fstat64(15, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(16) = 0 openat(15, "ide1", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 16 fstat64(16, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(15) = 0 close(16) = 0 access("/sys/devices/pci0000:00/0000:00:01.1/ide1/uevent", F_OK) = 0 readlinkat(AT_FDCWD, "/sys/devices/pci0000:00/0000:00:01.1/ide1/subsystem", 0x5f5b30, 4096) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 openat(15, "sys", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 16 fstat64(16, {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0 close(15) = 0 openat(16, "devices", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 fstat64(15, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(16) = 0 openat(15, "pci0000:00", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 16 fstat64(16, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(15) = 0 openat(16, "0000:00:01.1", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 fstat64(15, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(16) = 0 close(15) = 0 access("/sys/devices/pci0000:00/0000:00:01.1/uevent", F_OK) = 0 readlinkat(AT_FDCWD, "/sys/devices/pci0000:00/0000:00:01.1/subsystem", "../../../bus/pci", 4096) = 16 openat(AT_FDCWD, "/", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 openat(15, "sys", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 16 fstat64(16, {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0 close(15) = 0 openat(16, "devices", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 fstat64(15, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(16) = 0 openat(15, "pci0000:00", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 16 fstat64(16, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(15) = 0 close(16) = 0 access("/sys/devices/pci0000:00/uevent", F_OK) = 0 readlinkat(AT_FDCWD, "/sys/devices/pci0000:00/subsystem", 0x5f5b30, 4096) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 openat(15, "sys", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 16 fstat64(16, {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0 close(15) = 0 openat(16, "devices", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 fstat64(15, {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0 close(16) = 0 close(15) = 0 access("/sys/devices/uevent", F_OK) = -1 ENOENT (No such file or directory) readlinkat(AT_FDCWD, "/sys/devices/pci0000:00/0000:00:01.1/ide1/1.0/block/hdc/driver", 0x5f5b30, 4096) = -1 ENOENT (No such file or director) readlinkat(AT_FDCWD, "/sys/devices/pci0000:00/0000:00:01.1/ide1/1.0/driver", "../../../../../bus/ide/drivers/i"..., 4096) = 40 readlinkat(AT_FDCWD, "/sys/devices/pci0000:00/0000:00:01.1/ide1/driver", 0x5f5b30, 4096) = -1 ENOENT (No such file or directory) readlinkat(AT_FDCWD, "/sys/devices/pci0000:00/0000:00:01.1/driver", "../../../bus/pci/drivers/PIIX_ID"..., 4096) = 33 readlinkat(AT_FDCWD, "/sys/devices/pci0000:00/driver", 0x5f5b30, 4096) = -1 ENOENT (No such file or directory) lstat64("/dev/hdc", {st_mode=S_IFBLK|0660, st_rdev=makedev(0x16, 0), ...}) = 0 utimensat_time64(AT_FDCWD, "/dev/hdc", NULL, 0) = 0 lstat64("/dev/block/22:0", {st_mode=S_IFLNK|0777, st_size=6, ...}) = 0 readlinkat(AT_FDCWD, "/dev/block/22:0", "../hdc", 4096) = 6 utimensat_time64(AT_FDCWD, "/dev/block/22:0", NULL, AT_SYMLINK_NOFOLLOW) = 0 stat64("/run/udev/tags/systemd", {st_mode=S_IFDIR|0755, st_size=720, ...}) = 0 openat(AT_FDCWD, "/run/udev/tags/systemd/b22:0", O_RDONLY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 15 fstat64(15, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0 utimensat_time64(AT_FDCWD, "/proc/self/fd/15", NULL, 0) = 0 close(15) = 0 stat64("/run/udev/data", {st_mode=S_IFDIR|0755, st_size=4180, ...}) = 0 umask(077) = 022 getpid() = 404 clock_gettime64(CLOCK_MONOTONIC, {tv_sec=147, tv_nsec=105469823}) = 0 openat(AT_FDCWD, "/run/udev/data/.#b22:03qtXsM", O_RDWR|O_CREAT|O_EXCL|O_LARGEFILE|O_CLOEXEC, 0600) = 15 umask(022) = 077 fcntl64(15, F_GETFL) = 0x8002 (flags O_RDWR|O_LARGEFILE) fchmod(15, 0644) = 0 fstat64(15, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0 write(15, "I:4680519\nE:ID_FS_TYPE=\nG:system"..., 34) = 34 rename("/run/udev/data/.#b22:03qtXsM", "/run/udev/data/b22:0") = 0 close(15) = 0 close(6) = 0 sendmsg(14, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=0x000002}, msg_namelen=12, msg_iov=[{iov_base={{len=1969383788, type=0x65648 write(7, "", 0) = 0 epoll_wait(3, [{EPOLLIN, {u32=6274288, u64=6274288}}], 2, -1) = 1 Thanks, Zhe
